Experimental Study Of Nonlinear Electromagnetic Propagation And Interactions With Turbulent Magnetized Plasmas

Electromagnetic waves experience nonlinear scattering and anomalous absorption in turbulent magnetized plasmas. The plasma turbulence is referred to as the large density fluctuations in magnetized plasmas with a broad range of scale lengths. Nonlinear mode conversion and attenuation of electromagnetic waves occur when the waves are scattered off these plasma density fluctuations. Both laboratory and field experiments have been conducted to investigate the effects of plasma turbulence on electron cyclotron resonance absorption and the broadband electromagnetic wave attenuation due to the afore-mentioned processes. The laboratory experiments were carried out with a toroidal plasma chamber which produces magnetized plasmas with inherent plasma turbulence. Preliminary analysis, presented in a separate paper by Moriarty et al. (1991) at this meeting, indicates electromagnetic waves can be further weaked during the electron cyclotron resonance absorption in the presence of plasma turbulence as expected. Effort has been made to sort the physical processes which have contributed additively to the anomalous absorption of electromagnetic waves by turbulent plasmas. Field experiments, performed at Arecibo, Puerto Rico, assess the gross effect of plasma turbulence on the radar detection of the spacecrafts. The space plasma turbulence was artificially created by a ground-based HF heater. Results obtained in our latest ACTIVE space plasma experiments will be discussed. The experimental setup and theoretical basis of the laboratory and field experiments will be elucidated.