Stephen N. Paglieri1, Joseph R. Wermer2, Hailey M. Murdock2, Arthur Nobile, Jr.2, Hans W. Herrmann3, Thomas J. Venhaus2, James R. Langenbrunner3, and Joseph M. Mack3. (1) Tritium Science and Engineering, Los Alamos National Laboratory, P.O. Box 1663, MS-C927, Los Alamos, NM 87545, (2) Tritium Science & Engineering, Los Alamos National Laboratory, P.O. Box 1663, MS-C927, Los Alamos, NM 87545, (3) Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM 87545
A set of laser implosion experiments were conducted at the OMEGA laser at the University of Rochester, Laboratory for Laser Energetics (LLE) to study the effect of 3He concentration in DT-filled target shells on fusion yield in ICF implosions. Eleven laser fusion shells consisting of 1100-µm diameter, hollow, fused silica spheres with 4.6 to 4.7-µm-thick walls were loaded with 520 kPa of deuterium-tritium (DT) and then with 3He (101.3 or 520 kPa). The 3He permeabilities of the shells were determined by measuring the pressure rate of rise into a system with known volume. A mathematical method was developed that relied on the experimental fill pressure and time, and the rate of rise data to solve differential equations using MathCAD to simultaneously calculate 3He permeability and initial 3He partial pressure inside the shell. Because of the high permeation rate for 3He out of the shells compared to that for DT gas, shells had to be kept under 3He until immediately before being laser imploded or “shot” at LLE. The 3He partial pressure in each individual shell at shot time was calculated from the measured 3He permeability. Neutron and gamma yields from an implosion were shown to decrease with increasing 3He addition.