Fabrication of Thin CH and CD Films and Patterned Films Using a Heat Press Technique for the NIF and OMEGA Magnetic Recoil Neutron Spectrometer

Abstract

Deuterated polyethylene films as thin as 50 μm have been produced using a four-post heated press method. These films are then cut into the desired shape (foil) and are used for the magnetic recoil spectrometer (MRS). The MRS is a diagnostic tool for inertial confinement fusion (ICF) experiments at the National Ignition Facility (NIF) and at the OMEGA Laser Facility at the University of Rochester Laboratory for Laser Energetics. The films produced by this method are more uniform and have fewer defects than foils prepared by previous methods. Whereas traditional films had a thickness limitation of 100 μm, this new heat pressing method allows the fabrication of 50-μm films, which is the desired thickness for MRS foils. The foils produced and characterized by General Atomics have decreased the neutron measurement uncertainty of the MRS instrument by a factor of 2 compared to the previous foils. This work has also been extended to fabricate thin polymer films and films with sinusoidal patterns from other polymeric materials for ICF experiments. This paper will discuss the heat pressing technique used in the fabrication of these films for the NIF and OMEGA MRS as well as other patterned and flat polymer films. The morphology of these foils and the advantages that they provide will also be discussed.