A Statistical Discussion of Sets of Precise Astronomical by Edwin Bidwell Wilson

By Edwin Bidwell Wilson

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New Developments in Semiconductor Physics

This quantity comprises lecture notes and chosen contributed papers offered on the overseas summer time institution on New advancements in Semiconductor Physics held on the collage of Szeged, July 1-6, 1979. the main a part of the contributions during this quantity is said to the recent experimental technics and theoretical principles utilized in learn of recent semiconductor fabrics, as a rule III-V semiconductors.

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Coleman and R. C. Becker, IRE Trans. Microwave Theory Tech. 7,42-61(1959). ” Cambridge Univ. Press, London and New York, 1948. D. L. Webster, J . Appl. Phys. 10, 501-508 (1939). 3’ P. D. Coleman, IRE Trans. Microwawe Theory Tech. 11, 271-288 (1963). 28 2. FAR-INFRARED WAVE GENERATION one such linear generator developed at the University of Illinois,38 an average current of 5-30 mA of modulated 1 MeV electrons has been used. Harmonic power extraction has been achieved in higher mode cavities, Fabry-Perot resonators3’ and by means of beam-dielectric interactions leading to Cerenkov r a d i a t i ~ n .

Electrons at point C have an azimuthal velocity and those at C’ have velocity where E,, oBc is the radial component of the oscillating electric field. There is a difference in velocities, which means that electrons overtake one another and cluster in bunches or “spokes” of rotating space-charge, as shown in Fig. 14(b). The effect is called field focusing. As the electrons rotate they interact with the azimuthal component of the oscillating electric field. This does not alter the azimuthal drift velocity, but it does change the radial motions of individual electrons.

T h e higher harmonics are weakened by the inductance and capacitance shown in the equivalent circuit. The inductance tends to oppose these currents and the capacity tends to shunt them past the nonlinear resistance. In millimeter- and submillimeter-wave diodes, the shunting capacity must be reduced by minimizing the contact area. I t can be made as small as cm2; the barrier layer thickness is about cm. 05 pF. I t is capable of handling only low levels of power, a few hundred milliwatts. For a crystal current of 1 mA, the current density at the junction is lo5A cm-2.

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