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TJ-II:Experimental proposals: Difference between revisions
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== Experimental proposals, Spring 2024 == | |||
Creation date: 04/12/2023 10:21. Please do no edit this table. To submit a new proposal, please, use the link above. | |||
{| class="wikitable" | |||
! Title !! Main proponent !! Main proponent's affiliation !! Other proponents !! Specific objectives of the experiment | |||
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| 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. | |||
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| 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. | |||
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| 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. | |||
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| 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. | |||
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| 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. | |||
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| 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. | |||
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| 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. | |||
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| 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. | |||
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| 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. | |||
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| 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. | |||
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| 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. | |||
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| 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. | |||
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| AEs model validation: measuring iota profile in NBI plasmas ||Cappa, Álvaro||LNF-CIEMAT||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. | |||
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| 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. | |||
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| 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. | |||
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| 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. | |||
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| 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. | |||
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| 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 | |||
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| 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. | |||
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| 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 | |||
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| 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. | |||
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| 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. | |||
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| 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. | |||
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| 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 | |||
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| 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. | |||
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| 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. | |||
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| 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. | |||
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| 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 | |||
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| 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. | |||
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| 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. | |||
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| 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. | |||
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| 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. | |||
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| 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. | |||
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| 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. | |||
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| 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. | |||
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| 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." | |||
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| 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. | |||
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| 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. | |||
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| 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. | |||
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| 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)). | |||
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| 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. | |||
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== Experimental proposals, Spring 2023 == | == Experimental proposals, Spring 2023 == | ||
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| 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. | | 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. | ||
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