A MODIFIED INVERSE FREE-ELECTRON-LASER ACCELERATOR

DURING PHASE I, DESIGN STUDIES WILL BE UNDERTAKEN FOR A MODIFIED INVERSE FREE-ELECTRON-LASER ACCELERATOR. IN THIS DEVICE, ELECTRON BUNCHES ARE TRAPPED IN THE BEAT-WAVE POTENTIAL WELL CREATED WHEN A STRONG ELECTROMAGNETIC WAVE PROPAGATES ALONG A SPATIALLY-PERIODIC WIGGLER MAGNETIC FIELD. THE ELECTROMAGNETIC DRIVE POWER IS TO BE AT A WAVELENGTH OF UNDER 2 CM, WITH A POWER ABOVE 10 MW. MODIFICATIONS WILL BE INTRODUCED THAT ARE EXPECTED TO INCREASE THE ACCELERATION GRADIENT ABOVE THE CONVENTIONAL VALUE. THESE INCLUDE OPERATION NEAR WAVEGUIDE CUTOFF FOR THE RADIO FREQUENCY DRIVER, AND NEAR CYCLOTRON RESONANCE FROM AN AXIAL MAGNETIC FIELD. PRELIMINARY ESTIMATES SHOW THAT THESE MEASURES COULD ALLOW A COMPACT, INEXPENSIVE ACCELERATOR TO BE BUILT TO FURNISH A LOW-EMITTANCE 5 TO 35 MEV ELECTRON BEAM HAVING AT LEAST 10(9) PARTICLES IN A 5 PS BUNCH. IN PHASE II, IT IS PLANNED TO BUILD A DEMONSTRATION MODEL OF SUCH A MACHINE.