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The principles involved in the design of high-power and very high-power transistors are considered in brief. The important factors in high-gain, high-current transistor design are the emitter-injection efficiency, the emitter and collector planarity, and the base-bias high-current falloff. The fabrication techniques involved in the production of transistors to maximize the injection efficiency and planarity (by evaporation of aluminum electrodes) and minimize base bias drop (by choice of optimum emitter geometry), are discussed. The characteristics of devices capable of handling currents in the range from 1 to 10 amperes at very high common-emitter current gains ranging from 50 to above 300 are described.

The performance of a paraterphenyl-coated 1P21 multiplier has been studied in the extreme ultraviolet from 125 to 325 Å. The light source was a vacuum spark between aluminum electrodes with a peak current of 30 kA. A number of lines from the fourth, fifth, and sixth spectra of aluminum were observed and the results were compared with those of earlier work in this laboratory in which Kodak SWR photographic plates, a Bendix resistance-strip photomultiplier, and a sodium salicylate-coated photomultiplier were compared. The paraterphenyl, which was vacuum evaporated on a cover glass to a thickness of 2.74 mg/cm^2, was found to be stable over a period of at least 10 days in the vacuum spectrograph. Its relative efficiency in the range from 312 to 200 Å is more nearly constant than that of the other three detectors. Below 161 Å the response of all the detectors decreases. Paraterphenyl appears to be a sensitive and highly satisfactory detector in the region below 325 Å.

A study of the total radiation in the visible region from vacuum spark discharges between electrodes of aluminum, magnesium, copper, and carbon has been made. With a capacitance of 21.6 µf charged to potentials up to 20 kv and inductance variable from 2.4 to 45 µh, peak currents up to 65 000 amperes were obtained. Oscilloscope traces of the output voltage from a photocell show that for the underdamped discharge the light output closely follows the current oscillations, dropping to zero between current cycles. The maximum light intensity in a single spark train varies as the third to the seventh power of the peak discharge current, or with the 3/2 to the 7/2 power of the discharge energy, depending on the electrode material and the inductance. For a given electrode material, the exponent increases as the inductance is decreased, while at constant current the maximum light intensity decreases slightly as the inductance is decreased. With aluminum electrodes ranging from 12 to 116?inch in diameter, the maximum light intensity varies inversely with the electrode cross-sectional area. Estimates of current densities as high as 100 000 amperes per cm^2 in a 10 000-ampere aluminum spark were made from measurements of the anode spots on the electrodes. Bursts of luminous vapor from the anode, apparently not a part of the current-carrying column, appear to constitute the principal source of light in the critically damped aluminum spark.

An experimental study was made of film diodes based on a chalcogenide glass with symmetric and asymmetric electrodes and with two lower symmetric electrodes. Film diodes with aluminum electrodes can be used as varistors. The electrodes affect the shape of the current-voltage characteristics. Diodes having two lower electrodes have a longer useful lifetime than do those having an upper electrode and a lower one. Generation in the negative-resistance region is described.