A Gated Radiometer for Plasma Afterglow Study

In order to monitor the electron temperature during plasma afterglow experiments, a gated microwave radiometer has been developed. The radiometer differs from the usual Dicke type of radiometer in the input switching scheme and in the fact that a good time resolution is required. The radiometer to be described has a time resolution of one microsecond and a temperature sensitivity of about ten degrees Kelvin when measuring temperatures near room temperature. The response time when used with a repetitive afterglow is 20 seconds. Measurements of electron temperature in a decaying nitrogen plasma have been made duirng the initial 300 microseconds of the afterglow.