Low-Energy Charged-Particle Fusion Reactions

We have initiated a program at Los Alamos to measure cross sections for the charged-particle reactions D(t,n)4He, T(t,2n)4He, D(d,n)3He, and D(d,p)T that are fundamental to the understanding of controlled thermonuclear fusion. Interest in these processes is primarily in the region below 100-keV bombarding energy, and accordingly the design range for the measurements is 10-120 keV. Our desired accuracy is 5% or less, compared with present systematic uncertainties of up to 50%. The experiment features a negative ion source and highly stable injector for the low-energy beam, measurement of beam intensity with a precision calorimeter, a windowless cryogenic target, calibration of the target density with a high-energy Van-de-Graaff beam, and a time-of-flight laser spectrometer to determine the absolute energy. Preliminary data have been obtained on the d + d reactions while preparations are underway for introducing tritium into the system.