A 600kv Blumlein Modulator For An X-band Klystron

An X-band klystron modulator using a new type Blumlein and a magnetic switch was developed for the Japan Linear Collider (JLC) project. The specifications of this modulator are an output voltage of 600kV, a pulse length (flat-top) longer than 100ns, a pulse rise time less than 100ns and a rather high output impedance of several hundred ohms. To realize a compact modulator satisfying these specifications, helically wound conductors were used for the inner and middle conductors of the Blumlein. Details of the Blumlein with helical conductors and results of the performance tests are described. And it was confirmed that a pulse with flat-top length longer than 100ns can be generated by a 1m long Blumlein for 650/spl Omega/ impedance load.