RESEARCH ON NOISE IN CROSSED FIELD DEVICES.
CENTRE DE PHYSIQUE ELECTRONIQUE ET CORPUSCULAIRE ORSAY (FRANCE)
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The program of work was to develop a C.W. TPOM in order to study noise and spurious oscillations, seeking especially to reduce the amplitude of these parasitic phenomena. The first object was to realize a linear L-band tube of an experimental type, with the following features 20 dB gain for a current of about 100 mA applied power up to 1 kW delay ratio of the order of 20. Two sorts of lines were studied an interdigital line working on the direct space harmonic m1, and a meander line brazed on alumina slabs. It was found that the meander line has some obvious advantages as compared to the interdigital line the band width is wider coupling resistance is higher, with a smaller variation over the band matching is easier coupling to the fast mode is much lower but attenuation is greater. Experimental study of the noise figure was carried out on two types of guns a short space charge gun, and a gun with a screen-grid over cathode. In the first case, the noise figure is high and increases rapidly with current. The screengridded gun has a lower noise figure, of the order of 50 dB. Author