Antenna response to random electric fields due to thermodynamic density fluctuations in plasmas

Thermodynamic density fluctuations of positively and negatively charged components in a plasma are responsible for the occurrence of random electric fields. The response of an antenna to these fields may be characterized by the quadratic or power spectrum of the voltage fluctuations in a measuring device connected to the antenna. The response depends upon the antenna configuration and is described as a filtering effect in wave vector space. Theoretical quadratic spectra are presented for equilibrium plasmas streaming parallel to the antenna axis. The bulk velocity has a strong influence upon the shape of the spectra, especially as it produces a periodic structure