Lawrence Livermore’s National Ignition Facility (NIF) requires a radiation tolerant video camera to remotely monitor varied activities in and around the NIF target chamber. Our present suite of monitor cameras must be either, removed during high yield shots, requiring substantial resources or left in place which greatly reduces their life expectancy. Our goal was to develop a relatively inexpensive, radiation tolerant monitor camera which could be left in place during high yield laser experiments yet continue to give quality data for up to (5) years of operation or about 250 high yield shots. The camera was built around the CMOSIS CMV 2000 / 4000 sensor. Camera components were chosen based on their radiation tolerant performance at the Cobham radiation test facility in CO Springs. The prototype camera was tested both at Cobham and on the NIF during high yield shots. We will present test results as well as predictions for camera life expectancy.
At the National-Ignition-Facility (NIF) and other laser facilities, X-ray transmission photocathodes are used in streak cameras and pulse-dilation framing cameras with temporal resolution well below 100 ps. For X-ray imaging quality assurance, signal-to-noise ratios of at least a couple, and optimally higher, have to be achieved. The signal-to-noise ratio depends on the photon influence and the Detective Quantum Efficiency (DQE). X-ray photocathodes are notoriously noisy, since they have large pulse height distributions, and their DQE is both material and photon-energy dependent. Furthermore, for high temporal resolution, in pulse dilation instruments space charge effects may further limit the achievable signal-to-noise ratio. Here, we look into details on what to consider when choosing photocathode materials to optimize the achievable signal-to-noise and touch on further potential improvements using structured photocathodes.
At the National Ignition Facility, new designs for x-ray diagnostics and ICF targets place high energy density capacitors in the harsh radiation environment of the target chamber. In these applications, dielectric breakdown would be catastrophic. This study considers the behavior of three dielectric types in a prompt-dose radiation environment; aluminum electrolytic, multilayer ceramic, and metalized polypropylene. The experiments exposed the capacitors with a flash x-ray machine and measured the internal discharge from shot-to-shot for a range of doses. From the results, the thinner aluminum electrolytic dielectrics internally discharged less than the thicker ones. The results from the flash x-ray source were compared to a limited set of data taken in NIF’s neutron test-well. The aluminum electrolytic and metalized polypropylene capacitors did not fail while biased at their rated voltage during eight shots in NIF, mostly between 1e9 n/cm2 and 4e9 n/cm2.
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