A new multichannel soft x-ray framing camera for fusion experiments

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Abstract
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 broadband diagnostic (100 eV≤Δhν≤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 ∼2.5 keV 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 12 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 μm. We have already fielded this new instrument during x‐ray conversion experiments, using both low and high Z targets driven by 1–2 ns, ‘‘flattop’’ laser pulses. We will show the details of the instrument design and sample results from conversion experiments.