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Friedman, J.

Publications and source records attributed to Friedman, J..

26 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

Development of the dense plasma focus for short-pulse applications

The dense plasma focus (DPF) has long been considered a compact source for pulsed neutrons and has traditionally been optimized for the total neutron yield. Here, we describe the efforts to optimize the DPF for short-pulse applications by introducing a reentrant cathode at the end of the coaxial plasma gun. We reduced the resulting neutron pulse widths by an average of 21±921±9% from the traditional long-drift DPF design. Pulse widths and yields achieved from deuterium-tritium fusion at 2 MA are 61.8±30.761.8±30.7 ns FWHM and 1.84±0.49×10121.84±0.49×10 12 neutrons per shot. Simulations were conducted concurrently to elucidate the DPF operation and confirm the role of the reentrant cathode. Furthermore, a hybrid fluid-kinetic particle-in-cell modeling capability demonstrates correct sheath velocities, plasma instabilities, and fusion yield rates. Consistent with previous findings that the DPF is dominated by beam-target fusion from superthermal ions, we estimate that the thermonuclear contribution is at the 1% level.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2016

Dense Plasma Focus Diagnostic Suite for the Surrogate Static Test

A Neutron Diagnosed Subcritical Experiment (NDSE) has been proposed to measure the reactivity of a subcritical ($k_{eff} <$ 1:0) plutonium experiment. This experiment requires a short, high-intensity neutron pulse delivered to the target material with precise timing. A feasibility study for the NDSE is being conducted jointly by National Security Technologies, LLC, and Los Alamos National Laboratory at Area 11 of the Nevada National Security Site. The goals of this study include characterizing and developing the proposed neutron pulse source, the fast photon detection system, and the shielding system to suppress scattering backgrounds.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
NASA NTRS1974

Effect of cessation of late-night landing noise on sleep electrophysiology in the home

Simultaneous measurements of noise exposure and sleep electrophysiology were made in homes before and after cessation of nighttime aircraft landing noise. Six people were tested, all of whom had been exposed to intense aircraft noise for at least two years. Noise measurements indicated a large reduction in the hourly noise level during nighttime hours, but no charge during the daytime hours. Sleep measures indicated no dramatic changes in sleep patterns either immediately after a marked change in nocturnal noise exposure or approximately a month thereafter. No strong relationship was observed between noise level and sleep disturbances over the range from 60 to 90 db(A).

Pearsons, K. S.↗