AN APPLICATION OF CORRELATION RADIOMETRY TO THE STUDY OF PLASMA RADIATION

Several techniques of correlation radiometry of plasma radiation are developed and described. A method of measuring correlation by the direct interference of two microwave signals is applied to the radiation emitted from the plasma column at frequencies near the electron cyclotron harmonics. Applications for some other techniques in plasma diagnostics are also discussed. Strong correlation is found and measured as a function of magnetic field, gas pressure, and axial separation of two sources, for the enhanced emission from the plasma. This indicated that collective processes are responsible for the enhanced emission. These processes are identified by the dependence of correlation on the properties of the plasma. The measurements show an unusual dependence on magnetic field and axial separation, which suggests a particular model of the plasma emission processes which can give rise to enhanced emission. The model is discussed. It describes the enhanced radiation as the result of the conversion of slow electro-static waves propagating perpendicular to the magnetic field to fast radiating surface waves propagating along a critical layer in the plasma parallel to the magnetic field. The slow electro-static waves are produced by a beam-plasma interaction. (Author)