Focusing System With Permanent Magnets for Klystrons
Applying permanent magnet technology to beam focusing in klystrons can reduce power consumption and increase reliability. These features benefit a variety of applications especially for large facilities that use a large number of klystrons such as the International Linear Collider. The low magnetic field needed for the purpose allows us to use inexpensive ferrite magnets instead of rare earth magnets. In order to evaluate the feasibility of such a focusing system with ferrite magnets, a test model for 750 kW L-band klystron was constructed. As a result of the power test, we attained 94% of the output power compared to an electromagnet.
Status Report on Klystron Improvements
One of the main functions of the Klystron Group at SLAC is to prosecute a program of improvements of the high power pulsed klystrons used in the gallery, originally designed to operate at 250 kV with a peak power output of between 21 and 24 MW. 1 The initial upgrading of the klystron power was achieved by a minor improvement in efficiency but a substantial change in operating conditions; the beam voltage was raised from 250 to 270 kV beginning in 1970.2
Focusing of an Electron Beam by Periodic Fields
The problem of focusing long electron beams by means of magnetic or electric fields which vary periodically along the beam is considered. Four specific cases are discussed: periodic fields of the axially symmetric and quadrupole type with either electric or magnetic fields employed. The equations of motion are written and solutions obtained which show beam trajectories corresponding to essentially parallel flow. Under certain specified conditions only small ripples are present. Actual trajectories as plotted by the analog computer are shown and charts and equations are presented to aid in the design of practical periodic focusing systems.