A Tunable, Low-Voltage Reflex Klystron for Operation in the 50 to 60-kmc Band

Paqe . .568 . .566 . .568 .575 . .584 . .589 . .590 . .591 . .593 . .595 The design of a low-voltage tunable reflex klystron for continuous operation in the millimeter waveband poses a number of difficult problems most of which stem either directly or indirectly from the small physical size of the resonant cavity. In addition, we must contend with the unpleasant yet inescapable facts that klystron cavities become inherently poorer with increasing frequency and that both smoothness and freedom from stresses in cavity walls assume increasing importance. 563 570 TIIE BELL SYSTEM TECHNICAL JOURNAL, MAY 1955 Finally, if a long-life, oxide coated cathode is desired, that is, one operating at moderate surface current density, a somewhat delicate gun design problem must then be faced. Many techniques, both electrical and mechanical, successfully used in the centimeter region fail when applied to the design of a millimeterwave reflex klystron so that we are forced to look for alternatives, i.e., specialized solutions which satisfy the requirements peculiar to this frequency range. Also, since many of the problems are mechanical in nature, it is obvious that the electrical design of a tube of this type cannot proceed without unusually close attention to structural feasibility. Another obstacle to tube development in a relatively new frequency band is the lack of broadband waveguide components normally available for the determination of important tube parameters. The Ml805* reflex klystron is the outgrowth of development effort which was aimed at exploring the possibility of millimeter-wave generation by means of a low voltage tunable reflex klystron.