Design of radiative shock targets to enable improved diagnostic access

Summary form only given. Our group has been studying radiative shocks using laser targets that contain a gas, most often xenon. Our motivation includes the production of conditions in the laboratory relevant to astrophysical phenomena and astrophysical simulation codes. A specific phenomenon of interest is the production of a dense, collapsed layer in a given material. Past experiments have consisted of a drive disk made of a solid, dense, low-Z material, capping off one end of a polyimide tube, along with various components used in alignment and measurement. A fill tube for inserting xenon gas plugged the other end. A diagnostic viewed the target perpendicular to the tube and obtained an image of high density regions. Pending experiments will require different diagnostics to measure temperature and related quantities, and which therefore must view the shock along the axis of the tube instead of viewing it from the side. The new target design must provide access to the diagnostic which looks up the axis of the main polyimide cylinder. We plan to accomplish this by building a target with a thin film closing the end of the polyimide tube, in a geometry that allows a laser beam to push the thin film out of the way. This will open up the diagnostic view along the tube axis. The main variables in deciding upon the details of this design are the various types of polyimide arms, and thickness and material of the film at the end of the main cylinder. Determining the type of arm involves first investigating available materials and their cost, and second, evaluating the machining capabilities within the lab. Evaluating the proper film thickness and material will involve HYADES computer simulations, a one-dimensional, hydrodynamic code, which detail the behavior of polyimide (C₂₂H₁₀O₅N₂) and polyethylene (CH) films when varying the film thickness, and laser spot size. The shock must clear 500 mum within 10 ns in order to not interfere with the diagnostic and therefore ruin the data. We will show the final design of this target and examples of experimental prototypes