TJ-II:Experimental proposals

TJ-II Model

Updated TJ-II timeline

TJ-II yearly planning 2022-2023

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 2023

Creation date: 20/03/2023 08:45. Please do no edit this table. To submit a new proposal, please, use the link above.

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)	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

2021-12-21: TJ-II: Influence of magnetic configuration on filament dynamics
2022-01-13: TJ-II:Turbulence properties near a rational surface
2022-01-13: TJ-II: Zeff measurement using visible bremsstrahlung (VB) with NBI heating (II)
2022-01-13: TJ-II:Impurity transport studies by LILA-TOF detection. A Lithium Laser-Ablation based Time-of-Flight (LILA-TOF) diagnostic for measuring plasma edge ion temperature (II). Influence of toroidal plasma rotation
2022-01-13: TJ-II: Multipellet injection in NBI plasmas
2022-01-13: 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.
2022-01-18: TJ-II: On the search of Zonal Flows and the influence of Alfvén Eigenmodes in the TJ-II stellarator
2022-01-18: TJ-II:L-H transition studies: characterization of plasma turbulence using Gas Puff Imaging, Probes, Doppler reflectometry and HIBP diagnostics
2022-01-18: TJ-II: Spectroscopic studies of TESPEL-shell ablation clouds
2022-01-18: TJ-II: Studies of pellet plasmoid drift in different magnetic configurations
2022-01-18: TJ-II: SOL Temperature profiles using RFA role of edge radial electric fields
2022-01-18: TJ-II: Determination of the spatial periodicity of NBI-driven Alfvén Eigenmodes and study of its magnetic configuration dependence
2022-01-18: TJ-II:NBI1 vs. NBI2 heated plasma comparison
2022-01-18: TJ-II:Turbulence and flow measured at the 3/2 magnetic island using Doppler reflectometry
2022-01-18: TJ-II: Validation of neutral beam current drive
2022-01-19: TJ-II: impact of impurities on turbulence
2022-01-19: TJ-II: Combining retarding-field energy analyzer and electrostatic probes measurements, an approach to measure the phase relation between density and temperature fluctuations using RFA?
2022-01-20: TJ-II:Imaging of pelet cloud dynamics in TJ-II using Halpha and bremsstraahlung filters and a fast-frame camera
2022-01-20: TJ-II:Searching for AEs suppression scenarios using off-axis ECCD
2022-01-20: TJ-II: Influence of edge radial electric fields on impurity transport
2022-01-20: TJ-II: 2D mapping of plasma parameters using HIBP
2022-01-21: TJ-II: Measurements using Gas Puff Imaging system
2022-01-24: TJ-II: On the electrostatic transport driven by Alfvén modes and broadband turbulence in the plasma edge region of the TJ-II stellarator
2022-01-24: TJ-II: Calibration of the helical arrays of Mirnov coils
2022-03-28: TJ-II: Injection of TESPELs with compounds or multiple elements of interest for W7-X

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

Session allocation (April - June) ( April 6, Pending approval by the Access Committee).

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