The following switches are briefly discussed: (1) high pressure and vacuum spark gaps, (2) liquid dielectric gaps, (3) solid dielectrics, (4) nonlinear ferromagnetic materials, (5) semiconductors, superconductors, (6) ferroelectric switches, (7) exploding wires, and (8) plasma instabilities. (MOW)

Temporally, spectrally, and spatially resolved x-ray emission diagnostics are important tools in the study of the heating and compression of laser fusion targets by sub-nanosecond laser pulses. The use of the Livermore 15 psec resolution x-ray streak camera to make such measurements is reviewed. Temporal histories of spectrally resolved x-ray emission in the 1 to 10 keV range have been obtained. These data have served to further define the x-ray streak camera as a quantative diagnostic tool and have also provided data relating to the absorption and compression phases of laser heating. The x-ray streak camera has been used in conjunction with a specially designed pinhole imaging system to temporally record images of laser compressed targets with a spatial resolution of approximately 6 ..mu..m. Implosion characteristics are presented for experiments with glass microshell targets. The concept, development, and testing of an ultrafast framing camera for full two-dimensional time resolved imaging is discussed. A prototype camera, based on the image dissection-restoration concept, has achieved an approximately 200 psec frame period with a resolution of 50 ..mu..m.

A subnanosecond x-ray framing camera technique employing a fiber optics image dissector coupled to a 10 ps optical streak camera will be described. The output data from the streak camera can be reduced from photographic film or directly couple into a SEC Vidicon camera for immediate computer decoding of each scan line into a two dimensional picture. The use of the new subnanosecond plastic scintillator in front of the fiber optics dissector will also be discussed. The paper will include (1) the description of the basic principle, (2) fiber optics's image dissector construction, (3) time resolution considerations, and (4) experimental data on a prototype 7 by 7 array.

The long-term mechanical stability of strongly positive gravity anomalies (mascons) on the moon is evaluated from relevant physical characteristics of these bodies, from paleoselenotherms, and from the flow behavior of the lunar mantle. (auth)