A Blumlein type modulator for 100 MW-class X-band klystron

To achieve the high efficiency in the X-band pulsed klystron modulator for the main linac in Japan Linear Collider, a new modulator with the Blumlein type PFN was designed and fabricated. Two identical 12-stage PFN's of the 23 ohm characteristic impedance are set on the both sides of the 1 to 7 step-up pulse transformer. Simulations showed that with this pulse transformer, 500 ns 560 kV pulse of 200 ns rise time could be obtained with the droop of 2%. The design and some test results of the Blumlein type modulator and the pulse transformer are presented.<
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