STATE-OF-THE-ART OF KLYSTRONS .1.

After a short description of the basic principle of a Klystron present ly interesting models are considered. Especially the state of the art of multi-cavity amplifier Klystrons with internal and external resonat ors is discussed. With Klystrons in the classic design the CW-power co uld be extended to the lower MW-region. Ar increased beam voltages pul sepowers of some 100 MW are attained. The CW-tubes are used above all in the final stages of TV-transmitters, the pulse tubes to feed the ca vities of particle accelerators, In the last years the requirements wi th regard to power and frequency of the pulse power tubes have steadil y increased. A novel design using another mechanism for the density mo dulation of a high-current, relativistic hollow beam is under investig ation since 10 years. An enhancement oi the pulse power up to the GW-r egion is expected. From other variants of the Klystron the practically used inductive output tube (Klystrode) and the multiple-beam Klystron are discussed along with three further designs based on the Klystron principle which are in the grate of development.