Laser imprint measurement and mitigation experiments in spherical geometry on OMEGA and NIF
Abstract
NRL in collaboration with LLE is conducting a broad effort in laser imprint measurement and mitigation, with experiments on the Nike KrF laser and Nd:glass lasers Omega and NIF. An experimental platform is being developed on OMEGA to test imprint mitigation in spherical geometry using a high-Z coating technique pioneered in planar experiments on Nike. As demonstrated in our Omega EP experiments, a smooth prepulse is required to pre-expand the coating for order-of-magnitude imprint reduction. A low intensity, ISI-smoothed prepulse was used in the original Nike experiments, while an x-ray prepulse was used in the EP experiments. The OMEGA experiments aim to test both pre-expansion methods - an SSD-smoothed, few-ns duration laser prepulse as well as an x-ray prepulse, in spherical geometry. The NIF experiments intend to measure and mitigate laser imprint for direct drive at ignition scale. Areal mass non-uniformity amplified by RM/RT instability is measured using radiography of spherical shells.
Work supported by the US DOE/NNSA.- Publication:
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APS Division of Plasma Physics Meeting Abstracts
- Pub Date:
- 2019
- Bibcode:
- 2019APS..DPPPO7011K