Energy Loss and Microturbulence under Multipulse ECR Plasma Heating at the L-2M Stellarator


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Abstract

In experiments on multipulse on-axis electron cyclotron resonance heating (ECRH) of plasma by a series of microwave pulses at the L-2M stellarator, several phases of plasma energy loss were observed: the short stage of low-energy loss, the stage of rapid increase in energy loss, the quasi-steady stage, and the relaxation stage between the heating pulses. In the stage of rapid increase in energy loss, the energy loss power is two or more times higher than that in the relaxation stage at the same energy of the plasma column. Short-wavelength plasma density fluctuations were measured using both the ordinary and extraordinary microwave collective scattering technique. It is found that, in the quasi-steady stage, the amplitude of density fluctuations is much lower than that in the preceding heating stages. The fluctuation amplitude lowers just after the restructuring of the density profile and establishment of a steady-state hollow density profile due to the density pump-out effect. The amplitude of large-scale density fluctuations at the plasma periphery recorded by a Doppler reflectometer remains unchanged during the ECRH pulses and in the time intervals between them. However, when the stage of rapid increase in energy loss begins, the shape of the density fluctuation spectrum changes significantly. The initially narrow spectrum with one peak near the zero frequency broadens, the amplitude of the central peak decreases, and two additional peaks at frequencies of 0.7 and −0.7 MHz appear.

About the authors

G. M. Batanov

Prokhorov General Physics Institute of the Russian Academy of Sciences

Author for correspondence.
Email: batanov@fpl.gpi.ru
Russian Federation, Moscow, 119991

V. D. Borzosekov

Prokhorov General Physics Institute of the Russian Academy of Sciences

Author for correspondence.
Email: borzosekov@fpl.gpi.ru
Russian Federation, Moscow, 119991

D. G. Vasilkov

Prokhorov General Physics Institute of the Russian Academy of Sciences; Bauman Moscow State Technical University

Email: borzosekov@fpl.gpi.ru
Russian Federation, Moscow, 119991; Moscow, 105005

S. E. Grebenshchikov

Prokhorov General Physics Institute of the Russian Academy of Sciences

Email: borzosekov@fpl.gpi.ru
Russian Federation, Moscow, 119991

L. V. Kolik

Prokhorov General Physics Institute of the Russian Academy of Sciences

Email: borzosekov@fpl.gpi.ru
Russian Federation, Moscow, 119991

E. M. Konchekov

Prokhorov General Physics Institute of the Russian Academy of Sciences

Email: borzosekov@fpl.gpi.ru
Russian Federation, Moscow, 119991

A. A. Letunov

Prokhorov General Physics Institute of the Russian Academy of Sciences

Email: borzosekov@fpl.gpi.ru
Russian Federation, Moscow, 119991

A. E. Petrov

Prokhorov General Physics Institute of the Russian Academy of Sciences

Email: borzosekov@fpl.gpi.ru
Russian Federation, Moscow, 119991

V. D. Stepakhin

Prokhorov General Physics Institute of the Russian Academy of Sciences

Email: borzosekov@fpl.gpi.ru
Russian Federation, Moscow, 119991

N. K. Kharchev

Prokhorov General Physics Institute of the Russian Academy of Sciences

Email: borzosekov@fpl.gpi.ru
Russian Federation, Moscow, 119991

A. A. Kharchevskii

Prokhorov General Physics Institute of the Russian Academy of Sciences

Email: borzosekov@fpl.gpi.ru
Russian Federation, Moscow, 119991

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