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TJ-II:Experimental proposals: Difference between revisions
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→Experimental proposals, Spring 2023
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| 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. | | 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. | ||
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| 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. | |||
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| 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. | |||
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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 || 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.. | |||
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| 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. | |||
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| 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. | |||
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| 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. | |||
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| 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 | |||
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| 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. | |||
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| 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. | |||
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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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| 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. | |||
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| 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. | |||
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