A sensitive dispersion interferometer with high temporal resolution for electron density measurements

A dispersion interferometer with a sensitivity of up to 10−4 fringe shifts and a time resolution of about 1 ns was developed. This time resolution exceeds previous systems by three orders. The operation of the dispersion interferometer and its characteristic properties are discussed and the experimental setup of the installation is explained in detail. The stability of the interferometer was tested and it was shown that its operation point drifts less than 0.25 rad/h. The interferometer was used to investigate the high power ion diodes at the pulse generator KALIF, where focused proton beams with power densities of up to 1 TW/cm2 are generated. For the very first time the electron line density inside the diode gap, where the protons are accelerated, could be directly measured. The line density was on the order of several 1013 cm−2. A straightforward estimation of the line density using a simplified diode model proved to be in excellent agreement with the results. The dispersion interferometer can be used ...