TJ-II:Experimental proposals

TJ-II Model

Important documents

Presentation template for pre- and post-session reporting

Creation of a new proposal

To submit an experimental proposal, please use this form. The table below is updated manually by the campaign management.

Experimental proposals, Spring 2024

Creation date: 04/12/2023 10:21. Please do no edit this table. To submit a post-deadline proposal, please, use the link above.

Minutes of the TJ-II Access Committee Meeting, January 23, 2023 .

Title	Main proponent	Main proponent's affiliation	Other proponents	Specific objectives of the experiment
Impact of plasma current on L-H transitions at TJ-II	van Milligen, Boudewijn	CIEMAT	Teresa Estrada (CIEMAT), Isabel García-Cortés (CIEMAT), Benjamin Carreras (UC3M), Eduardo de la Cal (CIEMAT), Igor Voldiner (CIEMAT), Arturo Alonso (CIEMAT)	Recent work has clarified the important role of the net plasma current, Ip, in facilitating L-H confinement transitions. Draft: https://drive.google.com/file/d/1ca7hgen5--xt9yeYt0qhjMrMvgPEfAfP/view?usp=drive_link In the present study, we will verify this effect by systematically varying the plasma current using the external OH control coils.
Impact of rationals on Pellet Enhanced Confinement at TJ-II	García-Cortés, Isabel	CIEMAT	Kieran McCarthy (CIEMAT), Boudewijn van Milligen (CIEMAT), Benjamin Carreras (UC3M), Luis García (UC3M), Daniel Medina-Roque (CIEMAT)	Pellet Enhanced Confinement [L. García, I. García-Cortés, B. Carreras, K. McCarthy, and B. van Milligen. The effect of pellet injection on turbulent transport in TJ-II. Phys. Plasmas, 30:092303, 2023] is expected to vary with the radial location of low order rational surfaces in the plasma edge. The radial location of these rational surfaces can be controlled by modifying the plasma current using the external OH control coils.
Spectroscopic Gas Puff Imaging edge plasma characterisation	de la Cal, Eduardo	LNF-CIEMAT	Voldiner Igor, van Milligen Boudewijn	1. Commissioning of the new camera and image intensifier. 2. Continue the characterization of the edge plasma ne and Te profiles with other diagnostics. 3. Vary the He injection rate to look for possible local perturbation in the plasma edge. 4. Optimize the camera and image intensifier settings (recording speed, exposure time, active sensor area, amplification voltage) together with the He rate level to maximize the recording speed and SNR.
Origin of SOL turbulence	Wu	Southwestern Institute of Physics	Patrick H. Diamond (University of California San Diego), Min Xu (Southwestern Institute of Physics), Carlos Hidalgo (CIEMAT)	1. Understand the origin of SOL turbulence. According to Wu et al. 2023 NF, we consider edge turbulence spreading and local SOL interchange turbulence as the main origins of SOL turbulence. We quantify both mechanism and compare their contribution to the SOL turbulence. 2. Understand the impact of edge turbulence spreading on the SOL width. We try to clarify the relative contributions of turbulence spreading from the edge and local SOL production in determining the SOL widths.
Llight-impurity powder injection in TJ-II plasma edge	Alfonso de Castro Calles	CIEMAT	Kieran McCarthy (CIEMAT), Federico Nespoli (PPPL), Naoki Tamura (LHD)	This proposal will study the effect of injecting light impurity species, in the form of powder, in the TJ-II plasma edge region. Similar experiments were performed in the last campaign using lithium hydride powder and a positive effect on plasma confinement was found. Such effects were observed in other devices (LHD) using boron powder and complex physics questions related to amelioration of turbulent energy transport and real time wall conditioning effects were claimed to play a main role.
Turbulence characterization of pellet-induced enhanced confinement phase at TJII	Isabel García-Cortés	CIEMAT	K. McCarthy (CIEMAT), T. Estrada (CIEMAT, B. van Milligen (CIEMAT), HIBP group (CIEMAT, Institute of Plasma Physics, National Science Center Kharkov Institute of Physics and Technology, Kharkov 61108, Ukraine) and TJ-II Team	In TJ-II, cryogenic pellet fuelling is seen to induce bifurcation-like transitions to improved performance in terms of stored energy, energy confinement and fusion triple product, this being better than gas-puff scenarios for similar densities. However, understanding of the full underlying physics of such a high performance is unknown. A broad full characterization of this phase is needed. The wide range of TJ-II diagnostics can help study this, in particular, turbulence levels and properties.
Investigation of pellet cloud dynamics in TJ-II in the presence of magnetic island using fast-framing video observation	Kocsis, Gabor	Centre for Energy Research	Tamás Szepesi (Centre for Energy Research), Nerea Panadero (CIEMAT), Kieran McCarthy (CIEMAT), Julio Hernández-Sánchez (CIEMAT)	The aim is to study the interaction of H pellets and TESPELs with the plasma by evaluating fast-framing video data. Similar experiments have already been performed at TJ-II, in which drifting clouds were observed both with H and VB filters with time resolution up to 700 kHz. Last experiments indicated that magnetic islands can change the cloud drift, suppressing it. Thus, we propose to investigate this by varying the island location and size through which we shoot both H pellets and TESPEL.
Internal density measurements of plasmoid in hydrogen pellet	Motojima., Gen	NIFS	N. Panadero (CIEMAT), K. J. McCarthy (CIEMAT), S. Kado (Kyoto University)	The objective is to evaluate the plasmoid density of hydrogen pellets to understand the ablation. Measurement of plasmoid density has been conducted in LHD and Heliotron J. There is a difference between them, probably due to the difference in background plasma parameters. If the plasmoid density is also evaluated in TJ-II, it should help to understand the mechanism of pellet ablation. We have obtained initial data from previous experiments and would like to extend it in the current experiment.
Investigation of the impact of the fast-ion losses induced by pellet injection on the density limit in TJ-II plasmas	López-Miranda, Belén	CIEMAT	Nerea Panadero (CIEMAT), Alfonso Baciero (CIEMAT), Francisco Medina (CIEMAT), Ignacio Pastor (CIEMAT), Álvaro Cappa (CIEMAT), Andrés Bustos (CIEMAT), Juan Fraguas (CIEMAT), David Jiménez-Rey (CIEMAT), José Luis Velasco (CIEMAT), Pedro Pons-Vilallonga (CIEMAT), Arturo Alonso (CIEMAT), Claudia Salcuni (University of Trieste), Teresa Estrada (CIEMAT), Josep María Fontdecaba (CIEMAT), Raúl García (CIEMAT), Isabel García-Cortés (CIEMAT), Julio Hernández-Sánchez (CIEMAT), Daniel Medina (CIEMAT), Kieran Joseph McCarthy (CIEMAT), Jaime de la Riva (CIEMAT)	Stellarator plasmas can collapse prematurely, this is a challenge in reactor development, so methods are required to overcome the density limit (DL). The aim of this work is to study the impact on the DL of fast-ion (FI) losses after cryogenic pellet in the TJ-II. The injection of pellets contributes to increase the density above the Sudo limit and modifies the radial density profile, and FI losses affect plasma performance. The DL should be defined considering the role of these FI.
Commissioning of fast camera for LBO diagnostic	Panadero, Nerea	CIEMAT	B. López-Miranda (CIEMAT), J. Hernández-Sánchez (CIEMAT), E. de la Cal (CIEMAT), A. Baciero (CIEMAT), F. Medina (CIEMAT), I. Pastor (CIEMAT), R. García (CIEMAT)	In the last campaign, we tried to install the fast cameroa to determine the penetration of LBO impurities. However, the preliminary results were not entirely satisfactory. For this reason, thorough alignment, focusing and recordings of impurities injected into the plasma are required prior to the experimental sessions.
Commissioning of the spectral scanning system	López-Miranda, Belén	CIEMAT	Nerea Panadero (CIEMAT), Alfonso Baciero (CIEMAT), Raúl García-Gómez (CIEMAT), Francisco Medina (CIEMAT), Ignacio Pastor (CIEMAT)	During previous campaigns we employed the spectral scanning system in order to determine the Zeff of the plasma. However, the small signal obtained with the system required an improvement, by decreasing the spectral rotating mirror speed. Fort his reason, an upgrade is performed reducing this speed.
Commissioning of the new fast camera for spectroscopic gas puff imaging (SGPI) and pellet injection (PI)	Panadero, Nerea	CIEMAT	E de Cal (CIEMAT), Igor Voldiner (CIEMAT), R. García (CIEMAT), J. Hernández-Sánchez (CIEMAT)	A new fast camera (Photron Fastcam Nova S20) is now available for SGPI or PI experiments. It far exceeds current cameras capabilities, with megapixel recording speeds of up to 20 kfps with a texp, min = 0.2 μsm and max recording speed of 1 Mfps at reduced resolutions. After installation and out-of-window focusing, He and PI recordings in the plasma are required before the experimental sessions.
AEs model validation: measuring iota profile in NBI plasmas	Cappa, Álvaro	LNF-CIEMAT	K. McCarthy (CIEMAT), N. Panadero (CIEMAT), P. Pons-Villalonga (CIEMAT), O. Kozachok (CIEMAT) and TJ-II Team	The goal is to have MSE measurements in NBI plasmas exhibiting AEs activity. We expect this measurement to clarify one of the main uncertainties when AEs model validation is attempted.
Investigation of the impact of LBO impurity injection immediately after cryogenic hydrogen pellet injection (PI) on confinement time in the TJ-II plasmas	López-Miranda, Belén	CIEMAT	Nerea Panadero (CIEMAT), Alfonso Baciero (CIEMAT), Francisco Medina (CIEMAT), Ignacio Pastor (CIEMAT), Teresa Estrada (CIEMAT), Josep María Fontdecaba (CIEMAT), Raúl García (CIEMAT), Isabel García-Cortés (CIEMAT), Julio Hernández-Sánchez (CIEMAT), Daniel Medina (CIEMAT), Kieran Joseph McCarthy (CIEMAT), Jaime de la Riva (CIEMAT)	The aim of this experiment is to study the confinement time after PI & LBO impurities into ECRH TJ-II. This is of interest since PI causes transient changes in plasma kinetic profiles, Er and turbulence. A large PI into an on-axis ECRH discharge leads to a collapse with rapid energy losses and plasma termination. In addition, radiative cooling due to impurities affects the energy, and Te decays. We intend to investigate how impurity injection by LBO immediately after PI affects transport.
Investigation of the impact of impurity and cryogenic hydrogen pellet injection on the density limit in TJ-II plasmas	Panadero, Nerea	CIEMAT	B. López-Miranda (CIEMAT), A. Baciero (CIEMAT), F. Medina (CIEMAT), I. Pastor (CIEMAT), A. Alonso (CIEMAT), C. Salcuni (University of Trieste), T. Estrada (CIEMAT), J. M. Fontdecaba (CIEMAT), I. García-Cortés (CIEMAT), R. García (CIEMAT), J. Hernández-Sánchez (CIEMAT), D. Medina-Roque (CIEMAT), k. J. McCarthy (CIEMAT), J. De la Riva (CIEMAT)	Stellarator plasmas can collapse prematurely, this is a challenge in reactor development, so methods are required to overcome DL. Here we study this DL in the TJ-II and its dependence on pellets & LBO injections. H PI can modify the radial profile & improve plasma performance. It can also increase ne above the Sudo limit. Since radiation losses scale with the square of the ne, and heavy impurities cool the plasma, the DL should be defined by the radiation from the plasma edge light impurities.
Investigation of the impact of impurity and cryogenic deuterium pellet injection on the density limit in TJ-II plasmas	Panadero, Nerea	CIEMAT	B. López-Miranda (CIEMAT), A. Baciero (CIEMAT), F. Medina (CIEMAT), I. Pastor (CIEMAT), A. Alonso (CIEMAT), C. Salcuni (University of Trieste), T. Estrada (CIEMAT), J. M. Fontdecaba (CIEMAT), I. García-Cortés (CIEMAT), R. García (CIEMAT), J. Hernández-Sánchez (CIEMAT), D. Medina-Roque (CIEMAT), k. J. McCarthy (CIEMAT), J. De la Riva (CIEMAT)	Stellarator plasmas can collapse prematurely, this is a challenge in reactor development, so methods are required to overcome DL. Here we study this DL in the TJ-II and its dependence on pellets & LBO injections. D PI can modify the radial profile & improve plasma performance. It can also increase ne above the Sudo limit. Since radiation losses scale with the square of the ne, and heavy impurities cool the plasma, the DL should be defined by the radiation from the plasma edge light impurities.
Investigation of the impact of LBO impurity injection immediately after cryogenic hydrogen pellet injection (PI) on confinement time in the TJ-II plasmas	López-Miranda, Belén	CIEMAT	Nerea Panadero (CIEMAT), Alfonso Baciero (CIEMAT), Francisco Medina (CIEMAT), Ignacio Pastor (CIEMAT), Teresa Estrada (CIEMAT), Josep María Fontdecaba (CIEMAT), Raúl García (CIEMAT), Isabel García-Cortés (CIEMAT), Julio Hernández-Sánchez (CIEMAT), Daniel Medina (CIEMAT), Kieran Joseph McCarthy (CIEMAT), Jaime de la Riva (CIEMAT)	The aim of this experiment is to study the confinement time after PI & LBO impurities into ECRH TJ-II plasmas. This is of interest since PI causes transient changes in plasma kinetic profiles, Er and turbulence. A large PI into an on-axis ECRH leads to a collapse with rapid energy losses and plasma termination. Radiative cooling due to impurities affects the energy, and Te decays. We try to study the isotope effect in transport due to LBO injection inmediately after D or H PI in H/D plasmas.
Isotope effect on pellet-induced enhanced confinement in TJ-II	I. García-Cortés	I. Gracía-Cortés (CIEMAT)	K. McCarthy (CIEMAT), T. Estrada (CIEMAT, D. Medina-Roque (CIEMAT), N. Panadero (CIEMAT), HIBP group (CIEMAT, Institute of Plasma Physics, National Science Center Kharkov Institute of Physics and Technology, Kharkov 61108, Ukraine) and TJ-II Team	High-performance plasma scenarios are achieved in NBI-heated TJ-II discharges after pellet train injections. In addition to increased density, plasma diamagnetic energy rises with respect to reference discharges by up to 70%. To date, only H2 pellets have been injected into hydrogen plasmas. However, isotope effects are critical issues for future reactor operation. We propose to use different H/D pellet/plasma combinations to extent further the current TJ-II pellet and PiEC database
Continuation of studies of hydrogen pellet plasmoid drift in different magnetic configurations	Panadero, Nerea	CIEMAT	K. J. McCarthy (CIEMAT), B. López-Miranda (CIEMAT), K. J. McCarthy (CIEMAT), A. Baciero (CIEMAT), F. Medina (CIEMAT), I. Pastor (CIEMAT), J. M. Fontdecaba (CIEMAT), I. García-Cortés (CIEMAT), R. García (CIEMAT), J. Hernández-Sánchez (CIEMAT), D. Medina-Roque (CIEMAT), J. De la Riva (CIEMAT)	The main objective of this proposal is to quantify pellet plasmoid drift in the early stages of the homogenization process, and its relationship with rational surfaces for magnetic configurations with an iota profile lower than the standard configuration. In addition, experimental results will be compared with HPI2 predictions, since these experiments will be also part of the current effort to evaluate the stellarator version of HPI2 for the TJ-II, W7-X, LHD and Heliotron J devices.
Study of the influence of fast-ion losses induced by AEs in pure NBI-heated & combined ECR and NBI plasmas.	López-miranda, Belén	CIEMAT	Nerea Panadero (CIEMAT), Alfonso Baciero (CIEMAT), Francisco Medina (CIEMAT), Ignacio Pastor (CIEMAT), Álvaro Cappa (CIEMAT), Andrés Bustos (CIEMAT), Juan Fraguas (CIEMAT), David Jiménez-Rey (CIEMAT), José Luis Velasco (CIEMAT), Pedro Pons-Vilallonga (CIEMAT), Arturo Alonso (CIEMAT), Claudia Salcuni (University of Trieste), Teresa Estrada (CIEMAT), Josep María Fontdecaba (CIEMAT), Raúl García (CIEMAT), Isabel García-Cortés (CIEMAT), Julio Hernández-Sánchez (CIEMAT), Daniel Medina (CIEMAT), Kieran Joseph McCarthy (CIEMAT), Jaime de la Riva (CIEMAT)	In magnetic confinement fusion, fast-ions constitute a source of particles and free energy that, under certain conditions, drive various unstable MHD instabilities that significantly degrade fusion performance. In particular, the study of the impact of Alfvén Eigenmodes (AEs) is of special importance for controlling fast-ion transport across the magnetic field. The present experiment aims to study the influence of fast-ion losses induced by AEs in pure NBI-heated & overlapped ECR and NBI plasmas
Studies of deuterium pellet plasmoid drift in different magnetic configurations	Panadero, Nerea	CIEMAT	K. J. McCarthy (CIEMAT), B. López-Miranda (CIEMAT), K. J. McCarthy (CIEMAT), A. Baciero (CIEMAT), F. Medina (CIEMAT), I. Pastor (CIEMAT), J. M. Fontdecaba (CIEMAT), I. García-Cortés (CIEMAT), R. García (CIEMAT), J. Hernández-Sánchez (CIEMAT), D. Medina-Roque (CIEMAT), J. De la Riva (CIEMAT)	The aim of this proposal is to quantify the pellet plasmoid drift in the early stages of the homogenisation process for different hydrogen isotopes in either the working gas or the pellet. The idea is to study possible differences in plasmoid drift for different combinations of protium and deuterium. In addition, results will be compared with HPI2 predictions, as part of the current effort to evaluate the stellarator version of HPI2 for the TJ-II, W7-X, LHD and Heliotron J devices.
Assessment of the influence of pellet fuelling efficiency on the magnetic well in the TJ-II stellarator	Panadero, Nerea	CIEMAT	N. Panadero, K. J. McCarthy (CIEMAT), B. López-Miranda (CIEMAT), A. Baciero (CIEMAT), F. Medina (CIEMAT), I. Pastor (CIEMAT), J. M. Fontdecaba (CIEMAT), I. García-Cortés (CIEMAT), R. García (CIEMAT), J. Hernández-Sánchez (CIEMAT), C. Hidalgo (CIEMAT), D. Medina-Roque (CIEMAT), J. De la Riva (CIEMAT)	The aim of this proposal is to quantify the effect of the magnetic well (W) on pellet fuelling efficiency. This may be key as this magnitude could play a significant role in plasmoid behaviour. Therefore, it may be relevant for the development and design of fuelling by pellet injection (PI) in a stellarator reactor. Also, experimental results will be compared with HPI2 predictions, as part of the current effort to evaluate the stellarator version of HPI2 for the TJ-II, W7-X, LHD and Heliotron J.
Investigation of the impact of LBO impurity injection immediately after cryogenic deuterium pellet injection (PI) on confinement time in the TJ-II plasmas	López-Miranda, Belén	CIEMAT	Nerea Panadero (CIEMAT), Alfonso Baciero (CIEMAT), Francisco Medina (CIEMAT), Ignacio Pastor (CIEMAT), Teresa Estrada (CIEMAT), Josep María Fontdecaba (CIEMAT), Raúl García (CIEMAT), Isabel García-Cortés (CIEMAT), Julio Hernández-Sánchez (CIEMAT), Daniel Medina (CIEMAT), Kieran Joseph McCarthy (CIEMAT), Jaime de la Riva (CIEMAT).	The aim of this experiment is to study the confinement time after PI & LBO impurities into ECRH TJ-II plasmas. This is of interest since PI causes transient changes in plasma kinetic profiles, Er and turbulence. A large PI into an on-axis ECRH leads to a collapse with rapid energy losses and plasma termination. Radiative cooling due to impurities affects the energy, and Te decays. We try to study the isotope effect in transport due to LBO injection inmediately after D or H PI in H/D plasmas.
Study of the isotope effect into fast-ion losses in NBI-heated plasmas in the TJ-II stellarator.	López-Miranda, Belén	CIEMAT	Nerea Panadero (CIEMAT), Alfonso Baciero (CIEMAT), Francisco Medina (CIEMAT), Ignacio Pastor (CIEMAT), Álvaro Cappa (CIEMAT), Andrés Bustos (CIEMAT), Juan Fraguas (CIEMAT), David Jiménez-Rey (CIEMAT), José Luis Velasco (CIEMAT), Pedro Pons-Vilallonga (CIEMAT), Arturo Alonso (CIEMAT), Claudia Salcuni (University of Trieste), Teresa Estrada (CIEMAT), Josep María Fontdecaba (CIEMAT), Raúl García (CIEMAT), Jaime de la Riva (CIEMAT)	In MCF, FI are a source of particles and free energy that drive various unstable MHD instabilities that degrade fusion performance. Then, the power transferred to the main plasma decreases and its heating efficiency drops. FI losses depend on many factors, such as the working gas, energy, mass, source, pitch angle and charge of the ion, etc. Thus, experimental studies and theoretical validations of FI losses are required to understand the behaviour of fast particles in stellarators
Commissioning of Pellet Injector for Deuterium Pellets	Kieran McCarthy	Ciemat	Isabel García, Nerea Panadero	Hydrogen pellets have been injected into ECRH and NBI plasmas since 2014. With these, a large pellet database has been created for TJ-II. This has enabled investigation of pellet ablation, plasmoid drift, pellet deposition, fuelling efficiency, etc. Plasmoid drift, pellet particle deposition and efficiency should be isotope sensitive. It is intended to extent the TJ-II database to both D2 pellets. For this, tests need to be performed to achieve reliable D2 pellet formation and acceleration.
The influence of pellet start-time and separation times on improved performance in TJ-II NBI heated plasmas	Kieran McCarthy	Ciemat	Isabel García	Cryogenic pellet injection causes a step-like increase in density and significant improvements in performance (diamagnetic energy & energy confinement) of NBI-heated TJ-II plasmas. Additional injections further improve this, however, the pellet sizes and separations between pellets can determine if such a phase is maintained or if operational boundaries are reached. Multiple injections with varied separations will be made to maximize such improvements and investigate these limits in TJ-II.
Study of pre- and post-pellet injection phases with a Langmuir probe on the TJ II stellarator	Ivanova, Pavlina	Institute of Electronics, Bulgarian Academy of Sciences	Miglena Dimitrova (Institute of Plasma Physics, Czech Academy of Sciences), Embie Hasan (Institute of Electronics, Bulgarian Academy of Sciences) , Elmira Vasileva (Institute of Electronics, Bulgarian Academy of Sciences)	Pellet injection (PI) is performed on the TJ-II for fuelling and impurity transport studies. When NBI heating is used, a PI can induce an enhanced confinement phase. Langmuir probes are frequently used for acquiring plasma parameters in the SOL of stellarators. Determining plasma parameters using electric probes in the pre- and post-PI phase under various experimental conditions (ECRH and NBI phases) can contribute to understand the physical processes and effects of pellets in the SOL.
Impurity-hole plasmas in TJ-II	Daniel Medina Roque	CIEMAT	J.L. Velasco (CIEMAT), I. García-Cortés (CIEMAT), K. McCarthy (CIEMAT), N. Tamura (NIFS), TJ-II Team	Achieve a positive Er in the outer plasma region and a negative one in the inner part to reproduce the plasma conditions in impurity-hole phenomenon in LHD. Then, inject the same impurities in the edge by Laser Blow-Off (LBO) and in the core by TESPEL and analyze if there are significant differences in transport and confinement times for inter-machine comparison. This is a continuation of http://fusionwiki.ciemat.es/wiki/TJ-II:Comparison_of_transport_of_on-axis_and_off-axis_ECH-heated_plasmas
Injection of low-Z elements for turbulence reduction and confinement improvement for comparison with W7-X and LHD.	Federico Nespoli	PPPL	D. Medina-Roque (CIEMAT), A. de Castro (CIEMAT), I. García-Cortés (CIEMAT), K. McCarthy (CIEMAT), N.Tamura (NIFS)	It has been observed in LHD and W7-X that the injection of low-Z impurities can have beneficial effects on plasmas by stabilizing turbulence and thus improve confinement. If this effect overcomes the negative effect of lost plasma power due to strong radiation fluxes, which is normally the case for low-Z impurities, then low-Z injections can result in increments of ion temperature and plasma diamagnetic energy in TJ-II. The objective is to study this in TJ-II for inter-machine comparison.
TESPEL injections into the pellet-induced enhanced confinement phase of NBI plasmas to evaluate core impurity confinement during this phase	Daniel Medina-Roque	CIEMAT	K. McCarthy (CIEMAT), I. García-Cortés (CIEMAT), N. Tamura (NIFS), B. López-Miranda (CIEMAT), F. Medina Yela (CIEMAT), AND TJ-II TEAM	An enhanced energy confinement phase is induced in NBI-heated plasma of TJ-II by pellet injection. It is considered that impurity confinement maybe enhanced also during this phase. TESPEL allows tracer deposition in the high-density core region of such enhanced plasmas. Thus, TESPEL (core) and LBO (edge) results can thus provide new insights on impurity accumulation. Our results can be of significant interest for evaluating impurity confinement during pellet-induced enhanced performance in W7-X.
Impurity confinement dependence on TJ-II plasma temperature gradient by injecting different Z tracers for comparison with LHD	N. Tamura	NIFS (Japan)	D. Medina-Roque (CIEMAT), Isabel García Cortés (CIEMAT), Kieran McCarthy (CIEMAT), Belén López Miranda (CIEMAT), Nerea Panadero (CIEMAT), Alfonso Baciero (CIEMAT), René Bussiahn (IPP Greifswald)	Experimental results from the 24th LHD experimental campaign show a strong impact of ECRH deposition radial location on impurity confinement for a wide range of Z. Reduced peaking of Te profiles can result in significantly longer impurity confinement times and stronger degradation of plasma performance for high-Z elements. The goal of this experiment is to study the dependency of impurity confinement on target electron temperature gradient by repeating experiments already performed in LHD.
Checking the alignment of ECRH beams using power modulation	Cappa, Álvaro	LNF-CIEMAT	Martínez, José	Measure the power deposition profiles of both launched beam (ECH1 & ECH2) by means of fast power modulation (fmod>3 kHZ) aiming at detect possible misalignments.
Characterization of energy transport in TJ-II: Dependence on thermodynamic gradients and link to turbulence measurements.	Carralero, Daniel	CIEMAT	A. Alonso (CIEMAT), A. Baciero (CIEMAT), A. Cappa (CIEMAT), T. Estrada (CIEMAT), J. M. García-Regaña, O. Kozachek, B. López-Miranda (CIEMAT), J. Martinez (CIEMAT), K. McCarthy (CIEMAT), E. Sánchez, I. Pastor (CIEMAT), H. Thienpondt (CIEMAT), J.L. Velasco (CIEMAT).	The objective of this proposal is to carry out a characterization of the profiles of ion and electron heat fluxes in order to obtain the turbulent transport coefficients and their dependence on local gradients, to be compared to local measurements of fluctuation amplitudes (HIBP, DR) and turbulent transport (HIBP). Besides providing a complete descripion of transport in TJ-II, these measurements will allow a detailed validation of turbulent transport predictions carried with gyrokinetic codes.
Characterization and modelling of the parallel dynamics of impurity ions with parallel and anti-parallel collinear NBI injection	Jaime de la Riva	CIEMAT	Arturo Alonso, Kieran Maccarthy	Here we propose to study the transmission of momentum to the plasma produced by the injection of neutral particles and other possible effects on the flow of impurities produced by the NBI. Parallel experiments have been proposed in W7-X OP2.1 and LHD 24th and 25 campaign.
NBI1 vs. NBI2 heated plasma comparison: impact of radial electric field and turbulence on impurity concentration and plasma performance	Estrada, Teresa	CIEMAT	A. Baciero, A. Cappa, B. López-Miranda, K. McCarthy, F. Medina, I. Pastor, J. de la Riva, J.L. Velasco	NBI plasmas show differences that depend on injection direction, co- or counter-injection. Whereas the evolution of ne profiles is alike for both, Te, Zeff, Er and density turbulence profiles evolve differently, resulting in higher density limit and higher energy content for ctr-NBI. Experimental beam characterizations indicate that both present similar re-ionization losses & transmissions, while ASCOT simulations show more direct ion losses for co-NBI and slightly better efficiency for ctr-NBI.
Study on impurity content, radiative collapses and turbulence characterization in the vicinity of density limit in TJ-II	Salcuni Claudia	CIEMAT	Arturo Alonso (CIEMAT), Nerea Panadero (CIEMAT), Belén López-Miranda (CIEMAT),A. Baciero (CIEMAT), F. Medina (CIEMAT), I. Pastor (CIEMAT), T. Estrada (CIEMAT), J. M. Fontdecaba (CIEMAT), I. García-Cortés (CIEMAT), R. García (CIEMAT), J. Hernández-Sánchez (CIEMAT), D. Medina-Roque (CIEMAT), k. J. McCarthy (CIEMAT), J. De la Riva (CIEMAT)	"The main objective of this proposal is to assess density ramps profiles scanning magnetic field configurations, then analyze the impurity content and see which impurity species affects the most the power radiated inside the plasma. Hence, choose a correct operational density limit as well as specific magnetic field configuration and characterize turbulence properties in the vicinity of the operational density limit."
Combining retarding-field energy analyzer and electrostatic probes measurements, an approach to measure the phase relation between density and temperature fluctuations using RFA	Nedzelskiy, Igor	IPFN	Carlos Silva (IPFN), Igor Voldiner (CIEMAT)	Physics behind uncoupled transport channels is a relevant open question for understanding both ELM control techniques (e.g. using RMP) as part of the ITER base-line scenario and the development of plasma scenarios without ELMs (e.g. I-mode). Transport channel decoupling could be driven by any mechanism that leads to a modification of the cross-phase between density and temperature fluctuations caused by changing driving conditions.
Commissioning Analyzer B, HIBP2	José Luis de Pablos	LNF-Ciemat	Oleksandr Kozachok, Oleksandr Chmyga, Isabel García Cortes, B. van Milligen	HIBPs allows to measure the plasma potential and Er profiles and density fluctuations and coherence between them. The addition of new TREKs HV amplifiers allow to control independently the HIBP-B and HIBP2-A and increase the total current of the beam to allow better SNR. This could help in the measurement of Medium-Range Correlation plasma potential important for the experiment "Turbulence characterization of pellet-induced enhanced confinement phase at TJII" leaded by Isabel García.
External control of Zonal Flows	Jose Luis de Pablos	LNF-Ciemat	B.P. van Milligen (LNF-Ciemat), J.M. Barcala (Dpto Tecnología-Ciemat), A. Molinero (Dpto Tenologia-Ciemat), O. Kozachok (IPP-NSC KIPT), O. Chmyga (IPP-NSC KIPT), J. Romero (TAE), I. García-Cortes (LNF-Ciemat), C. Hidalgo(LNF-Ciemat)	Zonal flows are of fundamental importance for confinement in magnetically confined plasmas, as evidenced by the well-known H-mode, produced by a transport barrier in the edge of the plasma.The present proposal investigates the possibility of actively stimulating the development of such low-frequency zonal flows through feedback.
Particle and energy propagation with edge plasma polarization	Xiao, Chijin	University of Saskatchewan, Canada	Voldiner, Igor (CIEMAT)	The main objective of the proposal is to study the relationship between the particle/energy transport and the plasma velocity shear in the TJ-II stellarator. In addition to linear cross-correlation analyses, nonlinear cross-correlation analysis will be used to study the strength and direction of energy transport (ref: Phys. Rev. Lett. 79, 2458 (1997) - Nonlinear Radial Correlation of Electrostatic Fluctuations in the STOR-M Tokamak (aps.org)).
Assessment of the impact of background hydrogen isotope on impurity behaviour in TJ-II	Daniel Medina Roque	CIEMAT	Isabel García Cortés (CIEMAT), Kieran McCarthy (CIEMAT), Belén López Miranda (CIEMAT), Nerea Panadero (CIEMAT), Alfonso Baciero (CIEMAT), Naoki Tamura (NIFS), René Bussiahn (IPP Greifswald)	Experimental results in the LHD have shown that deuterium plasmas have better impurity confinement than hydrogen plasmas. TESPEL and LBO impurity injections will be performed into H2 and D2 plasmas with similar electron densities and temperatures in CERC and CIRC. This comparison between CERC and CIRC is very interesting because the sign of the radial electric field affects the sign of the convection velocity coefficient of the impurity transport and thus the impurity confinement time.

Experimental proposals, Spring 2023

Creation date: 20/03/2023 08:45. Please do no edit this table.

Minutes of the TJ-II Access Committee Meeting, March 28, 2023 .

Title	Main proponent	Main proponent's affiliation	Other proponents	Specific objectives of the experiment
Injection of cryogenic pellets in TJ-II operated with an inverted magnetic field	McCarthy, Kieran Joseph	Ciemat	García Cortés, Isabel	When a pellet is injected, it is ablated by plasma and clouds that detach from it should drift down the B-field gradient. In tokamaks, drifting facilitates efficient pellet fuelling for high-field side injection. However, in helical devices, the effect of such drifting is not clear. Thus, the inversion of the TJ-II B field provides a unique opportunity to compare cloud drifting and particle deposition in a helical device. No differences are expected but this needs experimental confirmation.
Rational surfaces, flows and radial structure in the TJ-II stellarator: Part II	van Milligen, Boudewijn	CIEMAT	Igor Voldiner (CIEMAT), Benjamin Carreras (UC3M)	We will expand the iota scan of Day 17/03/2022, reported in B.Ph.van Milligen et al., Plasma Phys. Control. Fusion 64 (2023), p. 055006. It revealed an interesting pattern of the poloidal flow velocity, v_theta, linked to low order rational surfaces. Using turbulence modelling, this pattern was shown to be due, likely, to the formation of a staircase pattern in the profiles. By expanding the scan range, here we will study the effect of several major rational surfaces (3/2, 8/5, 5/3).
Continuation of studies of pellet plasmoid drift in different magnetic configurations	Panadero, Nerea	CIEMAT	Kieran McCarthy (CIEMAT), Julio Hernández-Sánchez (CIEMAT), Isabel García-Cortés (CIEMAT), Daniel Medina-Roque (CIEMAT)	The main objective of this proposal is to quantify pellet plasmoid drift in the early stages of the homogenization process, and its relationship with rational surfaces for magnetic configurations with an iota profile lower than the standard configuration. In addition, experimental results will be compared with HPI2 predictions, since these experiments will be also part of the current effort to evaluate the stellarator version of HPI2 for the TJ-II, W7-X, LHD and Heliotron-J devices.
Spectroscopic Gas Puff Imaging (SGPI) for edge plasma characterisation	de la Cal, Eduardo	CIEMAT	Igor Voldiner (CIEMAT), Boudewijn van Milligen (CIEMAT)	Characterise the edge plasma boundary with the new SGPI system, with focus on 2-dimensional (2D) imaging of electron density (ne) and temperature (Te) turbulence and its coupling to neutrals.The SGPI diagnostic has shown in the last campaign the ability to obtain 2D measurements of the edge plasma ne and Te with a spatial resolution of , 4 mm and exposure times down to 10 microseconds.
Studying fast-ion losses induced by Alfvén Eigenmodes in NBI heated plasmas of the stellarator TJ-II	López-Miranda, Belén	CIEMAT	Baciero, Alfonso; Cappa, Álvaro; Medina, Francisco; Pons-Villalonga, Pedro	In magnetic confinement fusion, fast-ions constitute a source of particles and free energy that, under certain conditions, drive various unstable MHD instabilities that significantly degrade fusion performance. In particular, the study of the impact of Alfvén Eigenmodes (AEs) is of special importance for controlling fast-ion transport across the magnetic field. The present experiment aims to study the influence of fast-ion losses induced by AEs in pure NBI-heated & combined ECR and NBI plasmas.
Impact of the rotational transform on pellet-induced enhanced performance in the TJ-II stellarator	Carreras, Benjamin	UC3M	Isabel García Cortés (CIEMAT), Kieran McCarthy (CIEMAT), Boudewijn van Milligen (CIEMAT)	In recent work, we observed pellet-induced enhanced confinement at the TJ-II stellarator [reference]. Analysis suggest that this enhancement could be related to the formation of transport barriers associated with low-order rational surfaces. Using the C-mode, i.e., the continuous variation of the rotational transform, we intend to shed further light on this issue.
External control of ZF in the TJ-II stellarator	De Pablos, José Luis	LNF	B.P. van Milligen, J.M. Barcala, A. Molinero, O. Kozachok (KIPT), O. Chmyga(KIPT), J. Romero (TAE), C. Hidalgo	The present proposal investigates the possibility of actively stimulating and control the development of low-frequency zonal flows through feedback.
Plasma Characterisation with Deuterium pellet injection	Isabel García Cortés	CIEMAT	Kieran McCarthy (CIEMAT), Daniel Medina-Roque (CIEMAT), Nerea Panadero (CIEMAT)	"Enhanced confinement is seen in TJ-II NBI-heated plasmas after single H pellet injection. In addition to the expected rise of core electron density, the plasma diamagnetic energy content rises by up to 40% with respect to similar discharges without PI. Enhancement is larger (up to 70%) when multi-pellets are used. To date, only H pellets into hydrogen plasmas have been studied. Our proposal is to inject deuterium pellets into deuterium plasmas to explore the isotope effect on this PiEC phase.
Recommissioning of the CXRS/MSE systems	McCarthy, Kieran Joseph	Ciemat	Jaime de la Riva Villen (Ciemat), Isabel García Cortés (Ciemat)	TJ-II is equipped with a compact NBI for performing CXRS and MSE. The NBI has been non-operative for several years due to a vacuum leak. The leak has been located and repaired. It is intended to recommission the CXRS diagnostic during this campaign. CXRS allows obtaining radial measurements of ion temperature, ion toroidal and poloidal velocity and radial electric field. Once operational, it will be used to measure these parameters during the PiEC phases achieved after pellet injection.
TJ-II: Calibration of the helical arrays of Mirnov coils	Pons-Villalonga, Pedro	CIEMAT	Álvaro Cappa (CIEMAT)	Calibration of the arrays of Mirnov coils, which is essential to correctly determine the mode numbers of the MHD perturbations.
NBI1 vs. NBI2 heated plasma comparison under reversed field conditions	Estrada, Teresa	CIEMAT	Arturo Alonso (CIEMAT), Alvaro Cappa (CIEMAT), Belen Lopez-Miranda (CIEMAT), Francisco Medina (CIEMAT), Ignacio Pastor (CIEMAT), Jose Luis Velasco (CIEMAT), NBI team.	A systematic comparison of plasmas heated with co- or ctr-NBI shows differences in the maximum achievable density and stored energy; lower values are generally achieved in co-NBI heated plasmas associated to higher impurity accumulation. A more intense negative Er and a reduction in the turbulence are measured in co-NBI heated plasmas as compared to counter- NBI cases. The interpretation of the experimental observations would benefit from experiments carried out under reversed field conditions.
Internal density measurements of plasmoid in hydrogen pellet	Gen Motojima	National Institute for Fusion Science (NIFS)	Nerea Panadero, Kieran McCarthy, Shinichiro Kado(Kyoto Univ.)	The objective is to evaluate the plasmoid density in hydrogen pellet to understand the pellet ablation. The measurement of plasmoid density has been conducted in LHD and Heliotron J, there is a difference of plasmoid density in them probably due to the difference of background plasma parameters. If the plasmoid density is evaluated also in TJ-II, it must help the understanding of mechanism of pellet ablation.
Impurity hole plasmas in TJ-II	Daniel Medina Roque	CIEMAT	Jose Luis Velasco (CIEMAT), Kieran McCarthy (CIEMAT), Isabel García-Cortés (CIEMAT), Álvaro Cappa (CIEMAT), Belén López-Miranda (CIEMAT), Alfonso Baciero (CIEMAT), Francisco Medina (CIEMAT), Teresa Estrada (CIEMAT), Daniel Carralero (CIEMAT), Emmanouil Maragkoudakis (CIEMAT)	Achieve a positive radial electric field (Er) in the outer plasma region and a negative one in the inner part to reproduce the plasma conditions in the impurity-hole phenomenon in LHD. Then inject the same impurities in the edge by Laser Blow-Off (LBO) and in the core by TESPEL and analyze if there are significant differences in their transport and confinement time. This is a continuation of http://fusionwiki.ciemat.es/wiki/TJ-II:Comparison_of_transport_of_on-axis_and_off-axis_ECH-heated_plasmas
Flux suppression via turbulence amplitude and cross phase across radial electric field variation	Tatsuya, Kobayashi	NIFS		Anomalous cross-field transport suppression by radial electric field in torus plasmas is one of central research topics in fusion plasma physics. A prototypical example is the low-to-high confinement mode transition (L-H transition) triggered under a certain level of plasma heat input. In this experiment, we investigate how the turbulent transport is suppressed via the turbulence amplitude suppression and modification of cross phase between potential and density fluctuations.
Continuation of Imaging of pellet cloud dynamics observations in TJ-II using Halpha and bremsstrahlung filters and a fast-frame camera	Gabor Kocsis	Centre for Energy Research	Tamás Szepsi (Centre for Energy Research), Nerea Panadero (CIEMAT), Kieran McCarthy (CIEMAT), Julio Hernández-Sánchez (CIEMAT)	The aim of this proposal is to study the interaction of hydrogen and impurity pellets (TESPELs) with the stellarator plasma by evaluating fast-framing video data. Similar experiments have already been performed at TJ-II, in which drifting pellet clouds were observed. However, for hydrogen pellets, it was hard to recognize single clouds. Therefore, experiments with higher temporal resolution, in several scenarios and magnetic configurations, also using different optical filters, are now proposed.
Neutral beam current drive in reversed field configuration	Álvaro Cappa	CIEMAT	José Luis Velasco, J. Martínez	The goal of the experiment is to measure the amplitude of toroidal current driven by both NBIs in reversed field configuration and compare with the results obtained in the standard conditions.
The pulsed ECRH wall conditioning scenario for W7-X	Moiseenko, Vladimir	Division of Electricity, Angstrom Laboratory, Uppsala University, Uppsala, Sweden	Yurii Kovtun (KIPT), Andrei Goriaev (FZJ), Dirk Naujoks (IPP), Torsten Stange (IPP), Chandra-Prakash Dhard (IPP), Heinrich Laqua (IPP)	The main goal of the research proposed includes the study of the physical properties of pulsed ECRH wall conditioning discharges, their optimization, usage, and the wall conditioning process caused by them. The optimization studies aiming to shorten the plasma decay stage which gives an opportunity to decrease the time period between shots. Based on these studies, a scenario for wall conditioning at Wendelstein 7-X will be developed.
Optimisation of fast-ion confinement TJ-II plasmas	Garcia-Munoz, Manuel	University of Seville	Galdon-Quiroga (University of Seville), Van Vuuren (University of Seville), Viezzer (University of Seville), Gonzalez-Martin (University of Seville)	Optimisation of fast-ion confinement in TJ-II. Optimal TJ-II magnetic topology, kinetic profiles and NBI parameters for fast-ion confinement. AE control with localised ECRH / ECCD
Characterization and modelling of the parallel dynamics of impurity ions with and without continuous NBI injection.	Jaime de la Riva Villén	CIEMAT	Arturo Alonso, CIEMAT. Kieran Maccarthy	We propose to investigate the possible effect of NBI momentum injection on the net parallel velocity of the plasma ions and impurities analyzing measurements obtained by CXRS diagnostic. The net parallel velocity of the individual plasma species is a prediction of the neoclassical theory in non-symmetric system. The combination of these parallel flow fields results in the so-called bootstrap current, the accurate prediction of which is of importance in stellarator concepts.
CXRS flow measurements: Density and ECRH scan	Jaime de la Riva Villén	CIEMAT	Arturo Alonso, CIEMAT. Kieran Maccarthy, CIEMAT	The objective is to study trends in radial electric field and net parallel velocity profiles in different plasma conditions and magnetic configurations and comparing it with neoclassical expectations. The dependency on the line integrated density, the ECRH power and the magnetic configuration of the flow measurements will be analyzed.
New mechanisms for shear production?	DIF-PRADALIER Guilhem	CEA/IRFM	SARAZIN Yanick (CEA/IRFM)	Zonal flows (ZF) are ubiquitous and play a central role in the regulation of transport in tokamaks, stellarators and RFPs. It is commonly agreed that turbulent Reynolds stresses, product of ExB flow fluctuations is the main drive for ZF production. This has been questioned experimentally [1]. Theoretically and computationally [2,3] a diamagnetic contribution to ZF production has been evidenced, product of ExB and diamagnetic fluctuations. Experimentally testing this mechanism would be a first.
Exploring basic mechanisms for the density limit	DIF-PRADALIER Guilhem	CEA/IRFM	SARAZIN Yanick (CEA/IRFM)	Density limits ubiquitously appear in tokamaks, stellarators and RFPs. Competing mechanisms have been proposed, ranging from MHD/radiative cooling [1] and radiation collapse [2] to transport scenarios: linear changes in dominant edge mode [3] or collapse of the edge shear layer consecutive to depletion of the zonal flow (ZF) drive [4,5]. Testing these scenarios within the same experiments, with special emphasis on aspects of the latter shear collapse scenario is timely and of broad significance.
Combining retarding-field energy analyzer and electrostatic probes measurements, an approach to measure the phase relation between density and temperature fluctuations using RFA	Igor Nedzelskiy	IPFN	Carlos Silva (IPFN), Igor Voldiner (Ciemat), HIBP team	Physics behind uncoupled transport channels is a relevant open question for understanding both ELM control techniques (e.g. using RMP) as part of the ITER base-line scenario and the development of plasma scenarios without ELMs (e.g. I-mode). Transport channel decoupling could be driven by any mechanism that leads to a modification of the cross-phase between density and temperature fluctuations caused by changing driving conditions..
Assessment of the impact of background hydrogen isotope on the impurity behavior in TJ-II	Naoki Tamura	NIFS	Daniel Medina Roque (CIEMAT), Isabel García-Cortés (CIEMAT), Kieran McCarthy (CIEMAT)	Experimental results in LHD have shown that deuterium plasmas have better impurity confinement compared to hydrogen plasmas. Thus, TESPEL and LBO impurity injections will be performed into hydrogen and deuterium plasmas with similar electron density and temperature to assess the isotope effect of background hydrogen on the impurity behavior in TJ-II.
Continuation of studies of impurity injection by LBO technique with fast camera images	López-Miranda, Belén	CIEMAT	Panadero, Nerea; Baciero, A.; Estrada, T.; García-Regaña, J. M.; McCarthy, K. J.; Medina, D.; Medina, F., Ochando, M. A.; Pastor, I.; Velasco, J. L.	Near the transition to a Er>0, an increase in confinement time was observed. Here, we try to study the confinement time in ion-root regimes using LBO observing the transport process with fast camera images, continuing with previous works: http://fusionwiki.ciemat.es/wiki/TJ-II:_Impurity_injection_by_laser_blow-off_(LBO):_Confinement_and_transport_studies_of_high_Z_impurity_injection_by_LBO_in_ion-root_scenarios_(II)._Comparison_to_neoclassical_and_turbulence_simulations.
TESPEL injections in turbulence reduced plasmas via pellet injection	Daniel Medina Roque	CIEMAT	Isabel García-Cortés (CIEMAT), Kieran McCarthy (CIEMAT), Naoki Tamura (NIFS)	Characterize the impurity confinement with TESPEL and LBO injections in the transient turbulence reduction of Pellet Induced Enhanced Confinement plasmas to assess if impurities are confined for longer times and if the deposition location of the impurities play an important role.
Lithium hydride pellet injection in TJ-II plasmas	de Castro Calles, Alfonso	CIEMAT		Lithium pellet/powder injection has shown to drive positive effects on confinement linked to the very low plasma contamination level and decreased hydrogen recycling on the boundary with an special influence on ELM pacing and suppression in devices like NSTX and EAST tokamaks. In TJ-II, lithium hydride LiH) is pretended to be used as a surrogate for lithium due to more simple manipulation and the easier pellet fabrication when compared to pure Li pellets
Assessment of impurity screening in TJ-II	Naoki Tamura	NIFS	Daniel Medina Roque (CIEMAT), Isabel García-Cortés (CIEMAT), Kieran McCarthy (CIEMAT)	In LHD impurity screening features have been observed in high-density plasmas leading to higher impurity confinement times for core-deposited impurities via TESPEL in contrast with lower values for impurities deposited in the edge by both gas puffing and LBO. A density scan will be performed and impurities will be deposited by the different methods into reproducible plasma discharges to compare the impurity confinement times in the different cases.
Divertor configurations in TJ-II: scenario development	Alonso, Arturo	CIEMAT	Eduardo de la Cal (CIEMAT), Daniel Carralero (CIEMAT), Marcos G. Barriopedro (UPM)	The objective of this proposal is to establish reliable operation scenarios for island divertor-like configurations in TJ-II. These configurations are based on the m=2 or m=4 edge island chain for configurations with edge iota close to 2 and could provide a means to explore ID SOL physics in TJ-II.
Characterization of energy transport in TJ-II: Dependence on thermodynamic gradients and link to turbulence measurements.	Carralero, Daniel	CIEMAT	A. Alonso (CIEMAT), A. Baciero (CIEMAT), A. Cappa (CIEMAT), T. Estrada (CIEMAT), J. M. García-Regaña, O. Kozachek, B. López-Miranda (CIEMAT), J. Martinez (CIEMAT), K. McCarthy (CIEMAT), E. Sánchez, I. Pastor (CIEMAT), H. Thienpondt (CIEMAT), J.L. Velasco (CIEMAT).	The objective of this proposal is to carry out a characterization of the profiles of ion and electron heat fluxes in order to obtain the turbulent transport coefficients and their dependence on local gradients, to be compared to local measurements of fluctuation amplitudes (HIBP, DR) and turbulent transport (HIBP). Besides providing a complete descripion of transport in TJ-II, these measurements will allow a detailed validation of turbulent transport predictions carried with gyrokinetic codes.
Plasma termination experiments using TESPELs	Tamura, Naoki	National Institute for Fusion Science	Kieran J. McCarthy (Ciemat), Isabel García-Cortés (Ciemat), Daniel Medina-Roque (Ciemat), Andreas Dinklage (IPP), Hjördis Bouvain (IPP), Thomas Wegner (IPP), René Bussiahn (IPP)	The main objective of this proposal is to study the mechanisms of plasma termination in response to a massive impurity (carbon and tungsten) injection. In addition, the impact of the heat deposition profile on the termination process is also a topic to be investigated. Therefore, the proposed experiments will be done in ECR-heated and NBI-heated plasmas. And to get some ideas regarding the isotope effect on such phenomena, the experiments will be performed in hydrogen and deuterium plasmas.
Impact of impurities on turbulent transport	García Regaña, José Manuel	CIEMAT	J. M. García-Regaña (CIEMAT), A. Alonso, A. Baciero, I. Calvo, D. Carralero, T. Estrada, A. González-Jerez, B. López-Miranda, K. McCarthy, D. Tafalla, H. Thienpondt …	Deliberate injection of impurities has been used to access high ion temperature (Ti) scenarios with los turbulence in LHD and to increase transiently Ti in W7-X. Moreover, gyrokinetic simulations have confirmed that impurities can reduce or enhance turbulent fluctuations and heat fluxes, depending on the sign of the impurity density gradient. The present proposal aims at characterizing the role that impurities have on turbulent transport and, consequently, on the performance of TJ-II.
Measurements of electron adiabaticity and comparisons with gyrokinetic simulations	Yanna, Kaitlyn	MIT	Arturo Alonso (CIEMAT) and others	The proposals aims at quantifying the phase difference between electron density and electrostatic potential fluctuations and the two-point Gamma-ExB flux in plasmas with varying values of local density gradient. This proposal's objective is to compare the HIBP measurements of the above-mentioned quantities with the gyrokinetic simulations by Thienpondt et al.
HIBP-based investigation of the properties of Alfvén Eigendmodes	Kozachok, Oleksandr	KIPT	Oleksandr Chmyga (KIPT), Álvaro Cappa (CIEMAT), Arturo Alonso (CIEMAT)	Continue the characterisation of the AE spatial-temporal dynamics of the density and potential oscillations (symmetry, particle flux). The medium term goal is to validate model predictions.

Experimental proposals, Spring 2022

Deadline: January 24, 2022

Session allocation (February - March) ( Feb 18, Approved by the Access Committee on March 2, Minutes).

Session allocation (April - June) ( April 6, Approved by the Access Committee on April 8, Minutes).

Experimental proposals, Autumn 2021

Deadline: October 1, 2021

Experimental proposals, Spring 2021

Deadline: January 30, 2021

Resolution of the experimental proposals Autumn 2019 and Feb_2020

TJII_Access_Committee_February_2021_v1.pdf

Experimental proposals, Spring 2020

Deadline: January 23, 2020

Resolution of the experimental proposals Autumn 2019 and Feb_2020

20191122 TJII Access Committee Nov2019 v1.pdf

Experimental proposals, Autumn 2019

Deadline: October 15, 2019

Resolution of the experimental proposals Autumn 2019

20191122 TJII Access Committee Nov2019 v1.pdf

Experimental proposals, Spring 2019

Deadline: January 29, 2019

Resolution of the experimental proposals Spring 2019

20190301 TJII Access Committee Fe2019 final.pdf

Experimental proposals, Autumn 2018

Deadline: October 10, 2018

Resolution of the experimental proposals Autumn 2018

20181027 Plan TJII Nov Dec 2018 v6.pdf

Experimental proposals, Spring 2018

Deadline: March 7, 2018

Resolution of the experimental proposals Spring 2018

20180423 Plan TJII April June 2018 v11.pdf

Experimental proposals, Spring 2017

Deadline: January 26, 2017

Resolution of the experimental proposals Spring 2017

20170206 Plan TJII Feb June 2017 v15.pdf