Refractive index gradient diagnostics: Analysis of different optical systems and application to COBRA ion diode

Different optical system variations for refractive index gradient diagnostics with a laser-beam probe have been analyzed. A “three-telescope” optical system which permits simultaneous measurement of both the laser-beam centroid deflection by a bi-cell photodiode and the spatial Fourier spectrum of the deflected beam by a streak camera has been implemented on the COBRA ion diode. The dynamics of the anode plasma layer has been studied with these techniques.