Portable Cw Linac for Commercial Applications

This paper continues our description of a new compact CW linac program started by Schonberg Research Corporation (SRC) under terms of a development contract. This work is now continued by High Energy Systems (HES) Division of AS&E. HES has been formed based on the acquisition of SRC by AS&E. Since we published the design and the first experimental data on the 1 MeV CW linac [1], a complete test has been done as a continuation of the CW program. The accelerator is equipped with the local radiological shield and it can be operated on the manufacturing floor. The linac can be used for a variety of commercial and scientific applications, which require high power electron beams such as NDT programs, sterilization of medical products, electron beam processing of composites and food irradiation. In this paper, we will briefly describe the latest results and upgrades to the existing system. 1 UPGRADES TO SYSTEM DESIGN The block diagram of the upgraded system is shown in Fig.1. We have replaced the 30 kW magnetron with a 30 kW klystron, driven by a 1 W solid-state source. * High Energy Systems Division of AS&E (Santa Clara, California) *** Headquarters located in Billerica, Massachusetts ** Consultant Figure 1: System block diagram Electron beam is formed in the electron gun manufactured by Litton Industries (1). High voltage power supply (2) designed and built by HES provides 0 to 20 kV to the egun accelerating gap. From the electron gun, the electron beam is injected into a 1.3 m long linac section (3), where it is accelerated to the designed energy of 1 MeV. Two solenoids have been added to the existing three (4). Each solenoid is powered by a separate Sorenson power supply (5). The existing system is now capable of providing adjustable magnetic field close to 1000G peak, depending on the relative location of the solenoids. A 30 kW klystron (7) has replaced the magnetron operating at 2450 MHz. Upgraded Spellman power supply (8) is used to operate the klystron. The multiple beam klystron operating voltage range is similar to that of the previously used magnetron. A permanent periodic magnetic (PPM) focusing system used on this klystron permitting us to eliminate the electromagnet, used for the CW magnetron. A three-port RF circulator manufactured by AFT(13) is used to protect the klystron from the reflected power. All the components associated with the set-up using the magnetron, such as cooling fans for the magnetron “dome” window and the anode, 1 kW phase-locking klystron with power supply, the second RF circulator were removed from the existing system. The other components, described in [1] are unchanged. The assembly drawing which shows the linac position with respect to the “flying spot” wheel support is shown in Fig.2. Figure 2: Present linac incorporated into a “demo”system Other components such as magnetron, circulator, etc. have not been shown in order not to overload the drawing. 0-7803-5573-3/99/$10.00@1999 IEEE. 590 Proceedings of the 1999 Particle Accelerator Conference, New York, 1999