Production of overdense plasmas by launching 2,45 GHz electron cyclotron waves in a helical device

Ryosuke Ikeda (1) , Masaki Takeuchi (1) , Takafumi Ito (1) , Kazuo Toi (2) , Chihiro Suzuki (2) , Go Matsunaga (3) , Shoichi Okamura (2) , Chs Group (2)

1 Department of Energy Engineering and Science
2 NIFS - National Institute for Fusion Science
3 Japan Atomic Energy Research Institute

For production of low temperature plasmas with low collisionality, 2.45GHz microwave power up to 20kW is injected perpendicularly to the toroidal field at very low toroidal field Bt<0.1T. In the case Bt=0.0613T, the maximum electron density reaches three times of the O-mode cutoff density and the measured power deposition is concentrated in the plasma core region beyond the Left-hand cutoff layer. It clearly suggests that this over-dense plasma is produced and heated by electron Bernstein waves converted from the launched X-mode in the peripheral region with steep density gradient.

Domaines: Physique des plasmas [physics.plasm-ph]

Ryosuke Ikeda, Masaki Takeuchi, Takafumi Ito, Kazuo Toi, Chihiro Suzuki, et al.. Production of overdense plasmas by launching 2,45 GHz electron cyclotron waves in a helical device. 2004. ⟨hal-00001962⟩