Design considerations are described which have led to the development of a range of low power pulsed magnetrons at s, X, and J bands with peak powers in the range 0.15 to 35 kW, which display some or all of a number of performance characteristics.switch on even after long storage, low missing pulse rate, rapid rise and These include reliability in operation under shock and vibration, rapid fall of rf power, low jitter rate, operation at low ambient pressure and over wide temperature range, low temperature coefficient of frequency.anee is described. Current work on further understanding the parameters limited performlevel 50 dB less than final output power, at a rate approximately inversely Studies at X band show that power growth is exponential from a noise proportional to magnetic fie1.d and with a maximum, in a particular design, for a ratio of applied to threshold voltage of about 1.5. Jitter is caused by uncertainties in starting time due to noise, and may be reduced by injection of ing signal. a coherent signal. A reduction of 20 db may be obtained with a -40 dB prim-4.2 CROSSED-FIELD NOISE GENERATOR TUBES, R. R. Moats of War-Telephone Laboratories, Murray Hill, N. J. necke Electron Tubes, Inc., Des Plaines, Ill. and J. A. Arnaud of Bell erator tubes, which may be characterized as injected-beam forward-waveThis paper describes a .family of crossed-field power-output noise genplifier which amplifies the noise further and couples it to the external cir-devices. They consist of a noisy gun, a drift space, and a crossed-field amcuit. The frequency range, power, and efficiency are related closely to the band, or to be narrow-band and tunable, depending on the slow-wave struc-crossed-field amplifier characteristics, and thus may be made to be broadture. The slow-wave structures used have been meander lines or lumped-constant structures, all supported on beryllia ceramics. Criteria for the generation of noise in the gun are ,described. The noise generated is evaluated in terms of its frequency (or time) characteristic, and in terms of its amplitude distribution. The frequency or time domain characteristics are measured in terms of spectrum, or in terms of the auto-correlation function. Methods of evaluating the amplitude characteristics are described, including the sampling oscilloscope, and peak-to-average measurements.showing narrow-band and wide-band performance a t various power levels Particular characteristics of various noise generator tubes are described, and frequencies. Means of avoiding excessive peaks and dips in the spectrum include rf matching, internal shielding of the gun, and attenuation in the dc leads. High values of peak-to-average ratio of power amplitude are found, greatly exceeding the values possible in an efficient power amplifier.
