CROSSED FIELD HIGH-POWER WIDE BAND NOISE GENERATOR

Work has been carried out on a number of Penning discharge noise sources in attempts to increase the average power output, improve the efficiency and extend the upper operating frequency. In all these phases, limitations to the present noise source concept have now been found. Two of these limitations arise from the generation of large secondary emission currents from the end cathodes. This phenomenon tends to restrict both the maximum average power outputs to 10-100 W, and the maximum efficiency to approximately 25%. A third limitation is that of frequency. The nonresonant circuit, presently being used, has an upper frequency limit of approximately 200 Mc. This limit can be extended by using resonant circuits. However, the range of electronic tuning is then decreased. Because of these limitations immediate efforts are devoted to: manufacture of a limited number of developmental tubes with performances within the above bounds of power, efficiency and frequency; extension of the frequency range with resonant nonpropagating circuits; exploration of alternative interactions with non-reentrant propagating (or traveling wave) circuits.