Pyrolytic Removal of the Plastic Mandrel from Sputtered Beryllium Shells

Abstract

An engineering model is presented for the removal of the plastic mandrel from the inside of a sputtered Be shell. The removal is accomplished by forcing heated air in and out of the 4 to 5 µm laser drilled fill hole in the capsule wall by cycling the external pressure between 2 and 5 atm. The plastic is combusted to CO 2 and H 2 O by this exposure, thus removing the mandrel. Calculations are presented to evaluate the various parameters in the approach. Experimental confirmation of the effectiveness of the removal is shown.

Design and Use of a Novel Apparatus for Measuring Capsule Fill Hole Conductance

“…Focused ion beam (FIB) milling is presently being used to manufacture this counterbore after laser drilling of the fill hole and pyrolysis to remove the plastic mandrel has been completed. 7 Figure 1. ICF fill tube geometry for baseline ignition target design.…”

Micron-Scale Deep Hole Drilling for Beryllium Capsule Fill Applications

“…The 175 µm thick Be-Cu ablator is deposited 6,7 on a 15 µm thick CH mandrel 8 that is removed through pyrolysis 9 after the fill hole is drilled. Once drilled and pyrolized, a 12 µm diameter counterbore up to 20 µm deep will be machined over the fill hole and a 10 µm fill tube is then inserted and epoxied in place.…”