No abstract

Pure deuterium plasma discharge from plasma focus breeds 1.01 MeV tritons via the D(d,p)T fusion branch, which has the same cross section as the D(d,n)3He (En=2.45 MeV) fusion branch. Tritons are trapped in and collide with the background deuterium plasma, producing 14.1 MeV neutrons via the D(t,n)4He reaction. The paper presents published in preliminary form as well as unpublished experimental data and theoretical studies of the neutron yield ratio R=Yn(14.1 MeV)/Yn(2.45 MeV). The experimental data were obtained from 1 MJ Frascati plasma focus operated at W=490 kJ with pure deuterium plasma (in the early 1980s). Neutrons were monitored using the nuclear activation method and nuclear emulsions. The present theoretical analysis of the experimental data is based on an exact adaptation of the binary encounter theory developed by Gryzinski. It is found that the experimentally defined value 1⋅10−3<R<3⋅10−3 can be explained theoretically only if one considers that tritium burnup occurs in the plasma domains of very high density (n≳1021 cm−3), high temperature (kT≳1 keV), and short trapping time (t0≤20 ns). These domains are known as efficient traps of MeV ions but are not the main source of D(d,n)3He fusion.

No abstract

insulating layer broadens the range over which t h e device can operate, and improves device yield. This presentation will describe several fabrication methods developed a t MCNC for silicon column emitters. Micrographs of the completed structures and arrays will be included. In addition, equipment and methods for electrical characterization of these arrays will be described, and the latest test results will be shown. Nuclear reaction yields Y(HZ) induced by fast ions were measured by activation methods. An array of GMcounters measures the radioactivity from reaction products in the plasma deposited on or induced by D+ ions, on Cu foils wrapping the .detectors [ I , 21. DPF (W = 7 kJ) operates with plasmas of different compositions of high-Z (I2C, I4N, I60) and low-Z (2H, 3He) elements with comparable abundances. Reactions sensitive to the slow ion (Ei c 0.4 MeV) population are D(d, n) and 3He(d, p), while others (HZ-LZ) effectively require energies of LZ ions of Ei > I MeV. As an example in Figs. a and b are shown the relations between Y(HZ) and D(d, n) neutron yield, Yn. from the same discharge over a series of discharges with fillings consisting of * H + 3 H e + I60 and 2H+'4N+I6O. Y(HZ) is always recalculated to the values that would be obtained if the plasma were composed of two elements of equal atomic denstites [I]. Fig. c shows the relation between Y(HZ) induced in the plasma by trapped fast ions and on Cu foils by ejected fast D+ ions. For all considered plasma compositions, a quadratic dependance exists between Y(HZ, fast) and Y(LZ, slow) while the relation between Y(HZ, fast) induced simultaoeously in the plasma and in the external targets is linear. ( a ) ( b ) 111 J. S. Brzosko. V. Nardi, [ Z ] J. S. Brzosko. V. Nardi. Phys. Lett A155(1991)162

No abstract