Electron cyclotron resonance plasma excitation in a toroidal plasma

Y Yu,M Xu,S B Gong,Y F Wu,X R Duan,B D Yuan,Y Z Wen,H J Wang,T Lan,Z Liu,M Y Ye

doi:10.1063/1.5045096

Abstract

In this article, Electron Cyclotron Resonance (ECR) absorption, Upper-Hybrid Resonance (UHR) absorption and Electron Bernstein Wave (EBW) conversion are systematically confirmed in magnetically confined KT-5D plasma which is sole-excited by a magnetron source. A 2.45 GHz ECR system has been developed on the toroidal helimak KT-5D to produce and sustain a steady-state plasma. 0.98 kW electron cyclotron wave produced by the magnetron is injected into the vacuum chamber through rectangular waveguides with a power absorption efficiency of 40∼50%. A steady-state plasma is excited with a density of several 1016/m3 and electron temperature of up to 30 eV. The radial profile of plasma density shows that ECR absorption dominates the power deposition with a higher hydrogen pressure of at the order of 10-1 Pa, while UHR absorption dominates with a lower hydrogen pressure of at the order of 10-2 Pa. Plasma density in the discharge with a superimposed magnetic shear has demonstrated the wave conversion from ECR to EBW.

Highlights

Radio Frequency (RF) waves, whose frequency ranges from 300 kHz to 300 GHz, works as one of the main plasma heating sources in large tokamaks
RF waves work as a convenient way to produce and sustain plasmas in many other kinds of plasma devices, including Helimaks,[4] simple magnetic torus,[5] magnetic mirrors,[6] dipoles,[7] etc
We present the investigation of physics of plasma excitation by Electron Cyclotron Resonant (ECR) on KT-5D helimak, together with the experimental evidences of Upper Hybrid Resonance (UHR) and Electron Bernstein Wave (EBW) heating

Summary

Introduction

Radio Frequency (RF) waves, whose frequency ranges from 300 kHz to 300 GHz, works as one of the main plasma heating sources in large tokamaks. We present the investigation of physics of plasma excitation by ECR on KT-5D helimak, together with the experimental evidences of UHR and EBW heating. It is obvious that Rfig circles fit the RECR line fairly well, suggesting an effective pure ECR plasma excitation by microwave system on KT-5D device.

Results

Conclusion