Gene H. McCall

Harmonic generation and frequency mixing in laser-produced plasmas

Spectral measurements of light scattered at various angles from a laser‐produced plasma were made at the laser frequency ωL, and at ωL/2, 3ωL/2, 2ωL, 5ωL/2, and 3ωL using a mode‐locked Nd:glass laser to produce intensities of 1016 W/cm2 at the target. Signals were detected at ωL, 3ωL/2, and 2ωL, and their intensities relative to the incident intensity were determined. Upper bounds were set for the intensities at the other frequencies.

High Speed Inexpensive Photodiode Assembly

A photodiode assembly is described which incorporates a Hewlett‐Packard 5082–4220 diode in an impedance matched holder to produce a unit with a rise time of approximately 100 psec and a fall time of approximately 300 psec. The assembly was designed for detecting fast laser pulses, but it can be used for monitoring any high speed optical signal.

Microwave interferometer for shock wave, detonation, and material motion measurements

A microwave interferometer system which provides a continuous measurement of the position of interfaces, such as shock fronts, detonation fronts, or material surfaces, has been developed. The use of low‐mass microcoaxial cable, some of which is commercially available, and stripline for conducting the microwave signal into the interior of an experiment makes the perturbation of the measuring system on the experiment small. Other microwave systems have measured the time of peak amplitude of a reflected signal, but the present system with proper matching produces a continuous record of position as a function of time. It is believed that this technique can be used to replace most uses of electrical contact or fiber‐optic pins in high‐explosive experiments. The amount of data far exceeds that which it is possible to obtain from pins or optical fibers. The matching of the microcoax to the microwave generator has an important effect on the accuracy of the technique. The effect of matching on accuracy will be des...

Intensity filtration of laser light

The nonlinear optical properties of carbon disulfide and bleachable dyes are utilized to construct a variety of intensity filters for 1.06‐μm picosecond pulses. The principle object of the study was the development of a filter that discriminates against low intensities, but the devices may be easily adjusted to limit high‐intensity hot spots or combined to form positive or negative notch filters. Applications to other wevelengths and/or time regimes are possible. The devices also show promise as isolators and pulse shapers.

Base-line noise reduction in laser pulse trains

The intensity‐dependent rotation of elliptically polarized light by carbon disulfide is used to discriminate against low‐intensity laser light and pass high‐intensity pulses through crossed polarizers. The transmitted intensity is shown to be proportional to the third power of the incident intensity. This technique has been used to reduce base‐line noise and low‐intensity pulses in the output pulse train of a mode‐locked Nd : YAG oscillator.

BLAST WAVE PHYSICS: Conspiracy or coincidence? An amusing footnote to the saga of Manhattan Project espionage

This article is a report of thoughts and actions of the author. Therefore, when referring to the author, the pronoun, I, or, me, will frequently be used. Whether or not this conforms to formal usage, it is believed that it will make the meanings of the paper clearer than if another construction were used. When it is necessary to refer to others, an attempt will be made to make clear the identity of the person being described.

Uncertainties Associated With Inertial Fusion Ignition

At present the energy required to drive an inertial fusion implosion is not well-defined. In the past the energy predicted to produce a breakeven yield, where the thermonuclear energy release is equal to the driver energy, has varied from 103 to 106 joules. The reason for this large variation is partly that experiment and theory have now defined previously poorly understood physical effects and partly that more conservative estimates are now used for those effects which are not yet understood.