Phase-Free Acceleration of Charged Particles Using Rectangular Drift Tube-Loaded Cavities

Rectangular drift tube-loaded cavity resonators which were operated in the TE 101 mode have been tested for their use in a phase-free accelerator. Perturbing object measurements combined with numerical calculations show that the energy gain depends strongly on the shape of the drift tubes and on the position of the beams in the reference plane. Particles are accelerated in one direction within a range of about 10 cm using 25 cm wide drift tubes with straight and pointed shapes, respectively. The energy gain of one cavity has been measured directly at an electromagnetic field amplitude of 1.6 Gauss and an electron beam of 20 keV. The time averaged energy gai-n of 15 eV is in good agreement with the theory. An example of an accelerating device which might be used to produce a large circulating current of electrons of 50 MeV is sketched. The cavities are placed within the gaps of spiral ridge magnets.