X-Band RF Linear Accelerator

The Air Force Research Laboratory is seeking a high-current X-band electron linear accelerator with selectable output energies in the range of 5-15 MeV.  This device will eventually be used to investigate the generation of a current modulated pulse train.  Sem-Sol’s approach consists of two side-coupled standing-wave LINear ACcelerator (LINAC) sections driven by a single X-band klystron at 9.3 GHz.  The output pulse duration is 5 msec.  The waveguide run to the second linac section also contains a variable attenuator.  The first linac section is operated in nearly constant fashion, with energy variations mostly provided by selecting the desired amount of attenuation in the second waveguide feed.  The high voltage pulses are provided by a COTS solid-state modulator with a stepup voltage transformer (~125 kV for the klystron and ~30 kV for the gun).  The klystron is protected by a circulator/isolator in each waveguide feed. The electron source is a thermionic cathode. Auxiliary systems provide the high vacuum inside the accelerator, and temperature control of system components. A control/monitor system controls the modulator parameters and monitors various temperatures. It also monitors LINAC performance parameters as the temperatures of the source and LINAC vary, and it sends out a control signal to the source to keep its frequency well-matched to that of the two LINAC sections.  Phase II activities include all effort necessary to design, fabricate, test and deliver the X-band accelerator system.