RESUMO
Cavity Ring Down Spectroscopy (CRDS) is used to measure the D- absolute density produced in the helicon plasma reactor RAID (Resonant Antenna Ion Device) at the Swiss Plasma Center. The birdcage geometry of the helicon antenna produces a homogeneous, high-density plasma column (n e â 1.5 × 1018 m-3 in H2 and D2 at 0.3 Pa and 3 kW of input power) 1.4 m long. We present the CRDS experimental setup, its positioning on the RAID reactor, and how the mechanical and thermal effects of the plasma affect the measurement. First results in deuterium plasma confirm the production of negative ions (D-) with a significant density: an average value of 3.0 × 1016 m-3 of D- is obtained at 0.3 Pa and 5 kW of power input in Cs-free plasma. This result is in good agreement with calculations performed with the collisional radiative code YACORA.
RESUMO
Magnetized plasma discharges generated by a planar resonant rf network are investigated. A regime transition is observed above a magnetic field threshold, associated with rf waves propagating in the plasma and which present the characteristics of whistler waves. These wave heated regimes can be considered as analogous to conventional helicon discharges, but in planar geometry.