The plasma focus device, a form of linear pinch discharge, produces an intense x-ray and neutron (D2) burst from a magnetically heated dense plasma. Rapidly changing magnetic fields at pinch time generate large axial electric fields which accelerate electrons and ions. In the experiments reported here the x-ray production during the plasma pinch of a 96 kilojoule (at 20 kV) plasma focus device was measured.The purpose of these experiments was to evaluate the energy in accelerated electrons in the plasma focus device and to learn how to enhance these electron hursts. Well focused, megampere electron beams at a few hundred kilovolts, lasting less than 10 nanoseconds have applications in fusionable pellet heating experiments. (1) X-rays were monitored to evaluate these electron bursts using a defocusing bent crystal spectrometer, doubly diffused silicon (PIN) detectors, with Ross filters, thermoluminescent dosimeters (TLDs) with filters, and x-ray pinhole photography.Thermoluminescent dosimeters indicated maximum x-ray yields of 140 joules above 3 keV at 57.3 kilojoules stored energy (16 kV) for a conversion efficiency to x-rays of 0.2%. 40 joules are above 60 keV and 15 joules above 80 keV. The hard x-ray pulse typically rises in 3 ns and frequently has a pulse width less than 10 ns. The low energy x-ray spectrum consists almost entirely of lines from the high Z anode insert, and the high energy spectrum is characteristic of a nonthermal power law distribution with an exponent of 2.2 ± 0.8. Peak hard x-ray production is obtained at 1 torr deuterium in contrast to peak neutron production (3 x 1010) at 5 torr. The addition of argon reduces total x-ray yield and increases the relative fraction of soft x-rays.These measurements suggest that the plasma focus produces 1200 joules of electrons with an average energy of 150 keV, in 10 nanoseconds with a stored energy of 57.3 kilojoules. This is a power of 1.2 × 1011 watts and power density of 1.5 × 1013 watts cm−2.

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LAWRENCE UVERMORE LABORATORY MS, tlaio; April 27, U"T2 -NOTICE-This, report n prepared as an accotrat of work spaasored fay the United States Gofcrnment. Neither tt~ United States nor the United States Atomic Energy CaamiB»n, nor any of t^-cir employees, nor any of thek contractors, fecoatneton. or their cmpSoyees. makes any warrant, express or implied, or essoincs any legal EacOity or responsibility for the teem icy. com* pUteness or cieiqtoess of any inforcutioa, sppvitos, product or process diseased, cr represents that its tac would not iafriaie priYaiely owned rights. We have measured the conductivity induced in films of polyethylene, epoxy, polytetrafluoroethylene, polyethylene terephthalate, polyimide, and glass by 9 x rays at dose rates between 10 and 10 rads/sec (dose in air). The films were 0.05 to 1.25 mm thick. The x-ray spectrum peaked in the vicinity of 10 keV, and the x-ray pulse width was about 40 nsec FWHRI. X-ray-induced photocurrents were found to obey Ohm's law at low bias voltages (less than I kVl. Above 1 kV, however, we observed that the peak photoconductivity signals from some of the 0.05-mm-thick materials tegan to When the electrical components and circuitry of a warhead are exposed to a nuclear radiation environment, induced voltages and currents are generated that may be large enough to damage critical components and disable the warhead. In our continuing program at LL.L to under stand the mechanisms by which these voltages and electrical currents are gen erated, we are making careful laboratory measurements of charge emission from material surfaces as well as the charge displacement effects that occur within the bulk of the insulating layer under increase at a slightly faster than linear rate with bias voltage. The glass samples exhibited no appr.r^nt delaved conductivity, while the other sample materials shewed various amounts. The magnitude of the delayed conductivity in polytetrafluoro ethylene, polyethylene terephthalate, and polyimide depended on the electric field, ec an effect that is consistent with PooleFrenkel fie'.d-assis :eo carrier generation.

Monoenergetic neutron-capture gamma rays have been used to measure gamma-ray attenuation coefficients of beryllium, aluminum, copper, tin, and lead at energies of 5.435, 6.405, 7.725, and 10.833 MeV. These coefficients have been obtained with uncertainties of from 0.3 to 0.5%. Results are in reasonable agreement with calculated coefficients. Analysis of the results shows that, in the energy range studied, if Compton scattering can be calculated from the Klein-Nishina formula without radiative corrections, pair production in the Coulomb field of an electron is best predicted by the theory of Borsellino.