1 / 13

Nuclear Fusion Institute of Russian Research Centre “Kurchatov Institute”

Transport Barriers and H-mode in Regimes with Deuterium Pellets Injected into T-10 Plasma Heated by ECR A . A . Borschegovskiy, M . M . Dremin ,, A . M . Kakurin , S . V . Krylov , M . Yu . Nikulin , Yu.D.Pavlov, I . N . Roy, V . A . Zhuravlev.

lotta
Télécharger la présentation

Nuclear Fusion Institute of Russian Research Centre “Kurchatov Institute”

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Transport Barriers and H-mode in Regimes with Deuterium Pellets Injected into T-10 Plasma Heated by ECR A.A.Borschegovskiy,M.M.Dremin,, A.M.Kakurin, S.V.Krylov, M.Yu.Nikulin, Yu.D.Pavlov,I.N.Roy,V.A.Zhuravlev Nuclear Fusion Institute of Russian Research Centre “Kurchatov Institute” 21th IAEA Fusion Energy Conference, October 16-21, 2006, Chengdu, China

  2. LFS pellet injection LFS EC power perpendicular launching Scenario ofexperiments [1] Yu.D. Pavlov et al. 18th Fusion Energy Conference, IAEA-CN77/EXP/5/17, Sorrento, Italy, 2000. [2] Yu.D.Pavlov et al. 28th EPS Conference on Controlled Fusion and Pl. Phys., p4.020, Madeira, Portugal, 2001.

  3. Time evolution of the electron plasma density (central chord) in case of multiple pellet injection.

  4. Transport barrier formation. The injection of a deuterium pellet results in evident change of edge electron density profile. Edge density pedestal together with high density gradients (exceeding 1013 см-4) make up transport barriers typical for L-H transition [3]. ECR heating is the necessary requirement to trigger L-mode to H-mode transition during injection of deuterium pelletin Т-10 tokamak. Necessary HF-poweris about 2-3 timeslower then threshold level forL-H transition, estimatedaccording to ITER scaling. [3]L.R.Balor et al “Improved fueling transport barrier formation with pellet injection from different locations on DIII-D”, 18th Fusion Energy Conference, IAEA-CN77/EXP5/04, Sorrento, Italy 2000.

  5. The injection of a deuterium pelletalso results in evaluation of electron temperature profile. The barrier ”steps” appear in those plasma regions where according to the model calculations rational magnetic surfaces with small values of indexes m andn (i.e. q=1; 1.5; 2) are located.

  6. The injection of following pellet does not destroy these barriers on the electron temperature profile. Moreover an additional pellet injection makes transport barriers more pronounced without changing their location. Injection of deuterium pellets does not build up the transport barriers in OH discharges.

  7. Transport barriers are localized at the rational magnetic surfaces correspondingly to the value of plasma current in discharge.

  8. Improved confinement in T-10 tokamak is characterized by practically complete absence of ELMs (like Quiescent H-mode)[4]. However, after multiple deuterium pellet injection with ECR heating phenomena like ELMs Type III activity were observed in some of discharges. They are characterized by rather high frequency (~1 kHz) and take place under low heating power and high density. Pab=1200 KW [4] W.Suttrop et al, “Studies of the ‘Quiescent H-mode’ regime in ASDEX Upgrade and JET”, Nucl.Fusion, 2005, 45,721

  9. R R In act of ELM the MHD perturbation develops on the low field side of the plasma Poloidal distribution of the 22 magnetic probe signals during one ELM

  10. Partial destruction of external transport barrier occurs during ELM Type III consequence. After ELM activity stops, edge electron density gradient restores.

  11. ELM Type III consequencealso affects on a deeper plasma regions (r ~24cm). In particular central ion temperature, measured by neutral particle analyzer, drops by ~ 10% which is results in fast decrease of neutron yield by a factor of ~ 1.5. After ELM III disappearance, ion temperature and neutron yield restore quickly. Partial destruction of internal transport barrier during ELM III and its subsequent restoration affects accordingly on the electron temperature. ELM Type IIIactivity results in degradation of energy confinement in plasma.

  12. In case of the plasma density sustained by gas puffing , the energy confinement time saturation takes place in both ohmic and auxiliary ECRH regimes [5] The multiple deuterium pellet injection during auxiliary ECRH (Pinput ~1-1.2 MW) allows to keep the linear dependence of energy confinement time on electron plasma density under the conditions of improved confinement (Н-mode). Value of ННfactor: 1-1.4 [5]Yu V Esipchuk at al. “High density experiments with gas puffing and ECRH”, Plasma Physics and Control Fusion 45(2003) 793

  13. Summary • Injection of deuterium pellet in T-10 tokamak results in improved energy confinementand formation of external and internal transport barriers • RF powernecessary for L-H-like transition is about 2-3timeslower than threshold level estimation inaccordance with ITER scaling • As a result of multiple deuterium pellet injection with auxiliary ECRH ELMs Type III were observed in some of T-10 plasma discharges. • The multiple deuterium pellet injection during auxiliary ECRH allows to prolong the linear dependence of energy confinement time on electron plasma density. This work was supported by ROSATOM (contract 6.05.19.19.06.856), ROSNAUKA (contract 7069) and RFBR (NSH-2264.2006.2)

More Related