Measurements Of The D(D,N) And ³Hed,p) Reaction Yields For The 1-MJ Plasma Focus Device Operating With A D₂-³He Gas Mixture

The ratio R(D-D)/R(D-³He) of yields of fusion reactions was used as a diagnostic tool for studying the effective ion energy of plasma produced in the 1-MJ plasma focus device at Frascati. The device is operated in the neutron-optimized mode at energies of 250, 390, and 490 kJ. The reaction yields are determined by measuring the activity induced in the ⁶³ Cu(p,n)⁶³ Zn (E_p = 14.6 MeV) and ¹¹⁵ In(n,n')^115m In (E_n = 2.45 MeV) reactions. A detailed discussion of the energy slowing down of neutrons is given and a new calibration of the (p,n) cross section of the monitor reaction is performed. The measurements are carried out simultaneously for the end-on and side-on positions, and no significant differences are observed. A comparison with other experimental data is given. Conversion of the ratio of fusion reaction yields to ion temperatures or effective ion energies of streams interacting with a cold gas medium gives kT_t ≅ 14 keV or E_d(kT_e = 0.5 keV) = 72 keV, respectively.