Monitoring quality of plasma in plasma reactor or gas discharge laser - using test phase superimposed over excitation voltage to change frequency which is then used to determine electron density and temp. in plasma

摘要

Method of operating a reactor or gas discharge laser which uses a plasma by monitoring the electron density (ns) or electron temp. Te in the plasma in which the circuit induction (12) of the excitation circuit is raised to a known additional inductivity (30) and to the voltage (Uo) of the excitation circuit for the plasma with an excitation frequency fo which is smaller than the ionic plasma frequency fri, is superimposed a test pulse U(t) which brings about a dampened oscillation of the electrode current i(t) with a frequency f1 in a state of equilibrium. This frwquency f1 is measured and used together with the total capacity Co and the Debye length from the border layer capacity Cs to determine the quotient ns/Te. ADVANTAGE - By monitoring the plasma parameters reliable and reproducible plasmas can be produced. There is no need to use the prior art Langmuir probe which causes problems due to surface changes.