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Information × Registration Number 0224U032604, (0123U105352) , R & D reports Title Investigation of high-frequency discharges for wall conditioning of toroidal fusion devices popup.stage_title Дослідження високочастотних розрядів для чистки вакуумних поверхонь тороїдальних термоядерних пристроїв Head Kovtun Yurii V., Кандидат фізико-математичних наук Registration Date 26-11-2024 Organization Kovtun Yurii Viktorovych popup.description1 The main goal of the project is to contribute to the physical picture of high-frequency discharges for wall conditioning of toroidal fusion devices based on the analysis of experimental data obtained on the JET tokamak, LHD stellarator, and TOMAS toroidal device. The new knowledge gained from these studies will have an impact on the further development and improvement of wall conditioning technologies in large fusion devices. popup.description2  The results of the first experimental series to produce a plasma using the radio frequency discharge (RF) above the ion cyclotron frequency at relatively low magnetic fields (0.5-0.6 T) in the large helical device (LHD) are presented 1.43 MW of RF power produced target plasma with density up to 6×1018 m-3 to deuterium. Tangential NBI application into such a plasma increases plasma parameters. Electron temperatures up to ≈ 0.9 keV and densities up to ≈ 2.4×1019 m-3 had been achieved, and the maximum value of <βdia> was 2.6%. These experiments open possibilities for new regimes of LHD operation which are also interested to W7-X, including the production of plasma for wall conditioning. The experiments carried out in hydrogen at the TOMAS facility show the possibility of controlling plasma parameters such as temperature and electron density in the combined electron cyclotron resonance + radio frequency (ECR+RF) discharge. The propagation of radio frequency (RF) waves in hydrogen plasma in a weak magnetic field is analyzed. The injection of additional RF power into the ECR discharge allows us to change the flux of neutral particles and their distribution function. The ability to control the fluxes and energies of particles leaving the plasma volume is important to approach the conditions necessary to study plasma-surface interactions in wall conditioning and fusion edge plasmas. The studies of the RF discharge in the range of ion cyclotron frequencies in the atmosphere of hydrogen and helium at JET. The difference in the density of the plasma created by the RF discharge in hydrogen and helium at JET is due to the presence of a small hydrogen minor additions in helium and, accordingly, the propagation of waves in a plasma with a higher density than in hydrogen. It is observed that the helium concentration decreases with the number of pulses in RF discharges in hydrogen and per turn of hydrogen in RF discharges in helium. Product Description popup.authors Kovtun Yurii V. popup.nrat_date 2024-11-26 Close