Recent ECRH Experiments in the L-2 M Stellarator with the Use of a New High-Power Gyrotron

Abstract

The results of experiments on plasma confinement at ECRH power density up to 1.5 MW/m 3 are reported. It is shown that the results of measurements of the diamagnetism and poloidal rotation velocity of the plasma in the peripheral region agree with numerical calculations using a neoclassical model with allowance for anomalous losses. The correlation has been found between the low-frequency modulation of the gyrotron power radiation and the modulation of the radiation scattered by the turbulent plasma density fluctuations.

Wavelet analysis of the parameters of edge plasma fluctuations in the L-2M stellarator

“…The fast transitions bore a great resemblance to the processes observed in [2,12,13] including the classic L-H transitions [14]. In the fast TT, the plasma energy and density grow quickly and then saturate (figure 1), and the density parameter remains constant even after turning off the ECR-heating; the H α radiation intensity decreases and that of В 2 increases [1].…”

“…Wavelet analysis allows detecting the temporal changes in the process parameters [3] and that is why it is suitable for the time sample research in different plasma diagnostics: dispersion, interferometry, Doppler reflectometry etc. It is shown that the Morlet wavelet and the "Mexican hat" [4] allow to detect the moment of the fast TT, whereas applying the Haar wavelet [4] adds to this also evaluation of its duration in a good accordance with the theory [2] and reflects the slow TT characteristics in more detail than with the two other functions. 4 To whom any correspondence should be addressed 2.…”

“…4 To whom any correspondence should be addressed 2. Description of the experiment and signal processing Plasma generation and heating in the L-2M stellarator [1,2] were realized with the ECR method using the gyrotron complex MIG-3 [5]. In the experiments, the maximum power was 500 kW.…”

Microwave Reflection from the Region of Electron Cyclotron Resonance Heating in the L-2M Stellarator

“…We performed numerical calculations of the coefficient of reflection from the ECR region for the conditions corresponding to the experiments on ECR plasma heating at the second harmonic of the electron gyrofrequency in the L-2M stellarator [3]. Let us consider a plane X-wave propagating along the x axis and polarized in the (x, y) plane perpendicular to the external magnetic field B 0 (x)e z .…”

“…In our experiments on ECR heating of plasma in the L-2M stellarator (see, e.g., [3]), we have revealed microwave reflection from the region of the resonance at the second harmonic of the electron gyrofrequency (ω 0 ≈ 2ω ce , where ω 0 is the angular frequency of heating radiation and ω ce is the electron gyrofrequency) by analyzing backscattered gyrotron radiation [4,5].…”