DCLC driven wave propagation and mode conversion in the MIX-1 mirror system

In MIX-1, a washer gun produced plasma is injected through a long (1.3m) uniform guide field region into a 60 cm mirror cell. After injection, the system consists of a mirror-trapped plasma and an adjacent plasma column in the guide field region. The mirror cell plasma (n/sub e/ ≅ 10/sup 10/-10/sup 12/cm/sup -3/, T/sub i/ ≅ 100 eV, T/sub e/ ≅ 10 eV) is unstable to the drift cyclotron loss cone (DCLC) mode, while the neighboring guide region plasma (n/sub e/ ≅ 10/sup 11/-10/sup 12/cm/sup -3/, T/sub i/ ≅ T/sub e/ ≅ 10 eV) is microstable. Coupling of wave energy from the unstable mirror region into the guide plasma has been investigated for various magnetic field configurations. In the case B(Guide) > B(Mirror midplane), DCLC activity at the mirror midplane ion cyclotron frequency generates slow modes which propagate into the guide region with little attenuation. For B(Guide) < B(Mirror midplane), a resonance layer appears between the mirror cell and guide region at which strong ion cyclotron absorption is observed. In this case, weak conversion into a mode which has properties similar to an electrostatic ion cyclotron wave also occurs. This latter configuration is especially relevant to tandem mirror systems, in which a low field central cell is adjacent to a high field end cell which may be microunstable