Development of a helicon-wave excited plasma facility with high magnetic field for plasma–wall interactions studies

The high magnetic field helicon experiment system is a helicon wave plasma (HWP) source device in a high axial magnetic field ( B₀ ) developed for plasma–wall interactions studies for fusion reactors. This HWP was realized at low pressure (5 × 10⁻³ − 10 Pa) and a RF (radio frequency, 13.56 MHz) power (maximum power of 2 kW) using an internal right helical antenna (5 cm in diameter by 18 cm long) with a maximum B 0 of 6300 G. Ar HWP with electron density ~10¹⁸–10²⁰ m⁻³ and electron temperature ~4–7 eV was produced at high B₀ of 5100 G, with an RF power of 1500 W. Maximum Ar⁺ ion flux of 7.8 × 10²³ m⁻² s⁻¹ with a bright blue core plasma was obtained at a high B₀ of 2700 G and an RF power of 1500 W without bias. Plasma energy and mass spectrometer studies indicate that Ar⁺ ion-beams of 40.1 eV are formed, which are supersonic (~3.1c s). The effect of Ar HWP discharge cleaning on the wall conditioning are investigated by using the mass spectrometry. And the consequent plasma parameters will result in favorable wall conditioning with a removal rate of 1.1 × 10²⁴ N₂/m²h.