Investigation of other operating points for the RCA streak tube in the Lawrence Livermore National Laboratory streak camera

The soft x-ray streak camera uses the RCA C73435 streak tube body fitted with a removable x-ray cathode. The front of the streak tube is exposed to the vacuum of an experimental chamber, which is not entirely under the control of a streak camera operator. Occasionally, the vacuum becomes poor enough to cause corona and arcing from the cathode to the chamber wall. The corona problem is more difficult because the dimensions of the x-ray camera body are smaller than for the optical camera body. Therefore, we investigated the effects on camera performance of decreasing the accelerating voltage at the cathode from the customary 17 kV. Several operating points were evaluated and 12 kV cathode-to-anode with 5 kV cathode-to-grid were selected for more detailed investigation. Transverse spatial resolution and dynamic range were found to be essentially the same as at our normal operating point of 17 kV for the cathode and 2500 V on the grid. Magnification, sweep linearity and absolute sensitivity changed as expected. In the course of the investigation, we measured the dynamic range with our CCD readout system. The effect of Coulomb repulsion at the crossover point was also measured and found not to affect dynamic range