ELECTRON TEMPERATURE MEASURING METHOD WITH ASYMMETRICAL DOUBLE PROBE

摘要

PURPOSE:To improve a time response and an expense curtailment etc., by intermittently impressing AC voltage between two asymmetrical probes placed in a plasma, and measuring the variation part of the voltage produced by the impression in the state where a current is not flowing. CONSTITUTION:The output of a high frequency oscillator 1 and a square wave generation circuit 2 is modulated in a modulation circuit 3, then given between both probe electrodes of P1 and P2 via a transformer T and a condenser C. A filter 4 is to eliminate a higher harmonic component, and the output of the circuit 2 is detected as a reference signal with a detection circuit 5. The voltage between both probes of P1 and P2 becomes the voltage corresponding to a point Vf' at the period T1 when a high frequency signal is produced to the output of the circuit 3. And a point Vf corresponds to Vf' at the period T2 when the said signal is unproduced. This makes a detection output to a Vf-Vf' square wave. The size of Vf-Vf' depends on the amplitude of a modulation output signal, and an electron temperature can be determined by the relation.