2.45 GHz microwave plasmas at magnetic fields below ECR
O A Popov; S Y Shapoval; M D Yoder Jr; O A Popov; Microsci. Inc., Norwell, MA, USA; S Y Shapoval; Microsci. Inc., Norwell, MA, USA; M D Yoder Jr; Microsci. Inc., Norwell, MA, USA
Журнал:
Plasma Sources Science and Technology
Дата:
1992-03-01
Аннотация:
Microwave plasmas (f= omega /2 pi =2.45 GHz, 200-1000 W) were excited and maintained at low static magnetic fields, B=300-450 G and gas pressures of 0.2-10 mTorr. Two modes were found and studied: low plasma density mode with N<sub>e</sub><N<sub>cr</sub>=7.4*10<sup>10</sup> cm<sup>-3</sup>, and high (overdense, N<sub>e</sub>>N<sub>cr</sub>) plasma mode. The resonance transition from low- and high-mode plasma was observed when the magnetic field near the microwave introduction (vacuum) window was B<sub>w</sub>=435-440 G. It was attributed to the second gyratron harmonic resonance omega =2 omega <sub>BS</sub>. Mechanisms of microwave power absorption at B<B<sub>ce</sub>=875 G are discussed.
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