New multichannel soft x-ray framing camera for fusion experiments

摘要

Two dimensional, time resolved x-ray imaging is a principal technique used to study hot plasmas produced in laser heated targets. It can be used to study laser energy deposition within the irradiation spot, the spatial and temporal dependence of laser to x-ray conversion efficiency, electron transport and density profiles, mass ablation rates as well as x-ray driven implosions in inertial confinement fusion experiments. We have successfully developed a new soft x-ray framing camera which will allow us to record two-dimensional images at different times almost simultaneously. It is a broad band diagnostic (100 eV(le) (Delta)h(radical) (le) 400 eV) having three channels which can obtain x-ray images at four different times from laser driven targets. Its current configuration includes one 500 eV, one 1.0 keV and one (approximately)2.5 key channels. The two low energy channels resulted from pairing transmission filters to grazing x-ray mirrors. Other channel options can be implemented easily to measure other x-ray energies. Four different striplines coated on a microchannel plate are gated at different times. Each strip records three different images taken nearly simultaneously, one image per channel. The result is twelve x-ray images on film, four images per channel taken at four different times, with a nominal resolution of approximately 100 ps per image. The diagnostic's spatial resolution is approximately 10 (mu)m. We have already fielded this new instrument during x-ray conversion experiments, using both low and high Z targets driven by 1ns-2ns, ''flat top'' laser pulses. We will show the details of the instrument design and sample results from conversion experiments.