Rotating-Wave Electron Beam Accelerator (RWA)

Overview

The RWA accelerator developed by MTI uses a cylindrical cavity holding a transverse-magnetic field to accelerate electrons to higher energies. The accelerator is designed to operate at a frequency of 5.85 GHz and uses a set of electromagnets to provide the required magnetic field for acceleration of a 5 keV, 10 mA electron beam. With about 80 kilowatts of microwave power fed into the cavity, we have been able to successfully accelerate the 5 keV electron beam to ~760 keV.

Some of the RWA Applications:

• Medical Radiotherapy
• High-power Irradiation
• X-ray Probe

The RWA offers twice the efficiency of conventional small accelerators in addition to having a greater degree of simplicity and a more compact design.  Since the RWA requires half the electrical power to operate, this translates into a 50% savings in electrical power costs.

This accelerator has numerous possible applications including food processing, flue gas remediation, wastewater treatment, x-ray radiotherapy, electron beam welding, security x-ray imaging, spectroscopy machines, sterilization of medical and industrial waste, as well as materials processing.

Publications

	Study of Compact Rotating-wave Accelerators for Medical and Industrial Applications
	Development of a Compact Rotating-wave Electron Beam Accelerator

How does the RWA work?

The rotating-wave accelerator is composed of an electron source, a single short cavity and a focusing magnet.  When rf power is injected into the cavity a rotating mode is generated inside which presents an axially-oriented rotating electric field.  As electrons enter the cavity, due to the magnetic field produced by the magnet, they begin rotating about the device axis.  Under the proper conditions both the rf electric field and the electrons rotate synchronously about the axis at the same rate.  It is this synchronous interaction the one that allows the electrons to be gradually accelerated by the rotating field in a dc-like fashion.

Accelerated Electron Beam Energy

The figures below show a plot of the measured data and a picture of the accelerated beam obtained on a scintillator. We believe that this compact accelerator will be the basis for a new class of compact and affordable 1-10 MeV microwave accelerators for military, medical and industrial applications.

Table 1 lists the design parameters for the RWA prototype.

Sketches of the commercial RWA using a permanent magnet.

If you are interested in obtaining more information about this accelerator, please contact Dr. Jose E. Velazco, President of Microwave Technologies Inc. at (703) 250-6485.