Ion oscillation considerations for pulsed klystron amplifiers

Ion oscillations have always been a potential problem for linear beam amplifiers. CW klystron amplifiers designed for low-noise performance use a confined focused electron beam to avoid this problem but consequently pay a penalty in increased magnet size over brillouin focusing. Pulsed amplifiers are commonly designed in the same manner to assure low-noise performance. An investigation was conducted to determine the regions of pulsed operation susceptible to ion oscillations in order to allow selection of the appropriate focusing method. The results indicate there is a wide range of pulse conditions where brillouin focused (and PPM) amplifiers can be used with assurance of low-noise operation.