Some features of the dynamics of suprathermal electrons after RF heating off at the Uragan-3M stellarator plasmas

• Дата: 2019
• Автори: Zamanov, N.V., Pavlichenko, R.O., Kulaga, A.E.
• Формат: Стаття
• Мова: English
• Опубліковано: Національний науковий центр «Харківський фізико-технічний інститут» НАН України 2019
• Назва видання: Вопросы атомной науки и техники
• Теми: Plasma diagnostics
• Онлайн доступ: http://dspace.nbuv.gov.ua/handle/123456789/194906
• Назва журналу: Digital Library of Periodicals of National Academy of Sciences of Ukraine
• Цитувати: Some features of the dynamics of suprathermal electrons after RF heating off at the Uragan-3M stellarator plasmas / N.V. Zamanov, R.O. Pavlichenko, A.E. Kulaga // Problems of atomic science and technology. — 2019. — № 1. — С. 259-262. — Бібліогр.: 7 назв. — англ.

For the past decades the microwave radiometry is a routinely used as diagnostic tool to obtain the information on temporal evolution and radial profile of the electrons temperature at Uragan-3M torsatron plasma experiments. However, in the case of low plasma density operation we observe the high level of emission at the frequencies that match the second and third harmonics of the extraordinary mode of electron cyclotron emission (ECE), after RF heating pulse off. This effect could be explained with the production of the suprathermal electrons. The present work describes the suprathermal electrons (SE) dynamics after turning off the RF heat pulse at the Uragan-3M torsatron (ne=2·10¹² cm⁻³ Te=300 eV, PRF=115 kW, B0=0.69 T). In the absence of the well-known suppressive echniques (resonant magnetic perturbations and massive gas injection) an attempt was made to describe the factors, which contribute to the generation of the suprathermal electrons for the Uragan-3M plasmas. The temporal evolution of the ECE emission intensity and it dependence on the working gas pressure in the torsatron vacuum chamber is presented. The level of the ECE emission shows strong correlation with other diagnostics (plasma density, plasma current, HXR and Hα emission intensity). The gradual increase of the pressure (after RF off) could be is one of the reasons that temporarily sustain the process of electron acceleration. The dependence of the time ECE emission on the rate in magnetic field change (δB) is also given.