Variable-Phase Asynchronous Cyclotron

The conceptual design of a Variable-Phase Asynchronous Cyclotron (VPAC) is describe, which provides longitudinal bunch compression of accelerated proton or ion beams, and thus, permits high current acceleration at higher accelerator efficiency, where the possible beam losses are minimized and the accelerator's mechanical tolerances are relaxed. Beam control is assured by the ability to independently set and vary the acceleration phase and rf voltage amplitude, the inter-cavity harmonic number and the transverse focusing strength, which considerably overcome the space charge effects in each sector and turn of the proposed cyclotron. The new accelerator concept is especially suitable to accelerate intense proton beams up to 800 MeV in energy and average beam current in the 100-mA class. All accelerator elements are based on currently available and feasible technologies. To demonstrate feasibility of design, the detailed calculations and modeling of a 10-turn VPAC prototype for the production of 25.6 MeV, 100 mA proton beam are presented and the key features of the new accelerator concept are discussed.