Acceleration scenario and Necessary Devices for The KEK-Digital Accelerator

A novel ion accelerator referred to as a digital accelerator, which is based on the induction synchrotron concept, is discussed here. Its operational performance is the same as that of the induction synchrotron, where acceleration and confinement of ions in the propagation direction are implemented independently with a pulsed voltage and the so-called barrier voltages. These voltage pulses are generated in the induction acceleration cell energized by the switching power supply, which is triggered with a trigger signal manipulated by an ion-bunch signal. In the digital accelerator, any ion species with its possible charge state can be accelerated since the acceleration voltage pulse generation is always synchronized with the ion circulation. Acceleration of argon ions is planned as a proof-of-principle experiment at KEK. The detailed aspects of the digital accelerator are described, including theoretical backgrounds such as beam dynamics. The KEK-PS booster synchrotron is under renovation, aiming to become the first digital accelerator. The KEK Booster is a rapid-cycle synchrotron where the acceleration voltage amplitude changes dynamically throughout the acceleration period. The existing induction cells can provide a peak output voltage of 2 kV in 250 nsec pulse width at a maximum repetition rate of 1 MHz. Once the peak output voltage is fixed, it is difficult to change its magnitude in the same acceleration cycle. The main purpose of this thesis is to propose the realization of a dynamically changeable acceleration voltage by employing the induction acceleration system. In fact, this idea has been developed for the KEK digital accelerator. The acceleration period is divided into stages, where different acceleration voltages, pulse widths, and repetition rates are required. A novel technique, which consists of staging of the acceleration period, systematic sorting of the induction acceleration cells, and intermittent operation of the induction acceleration systems, has been developed. Particle tracking simulations in the longitudinal direction were performed in order to verify the feasibility of the scheme. The acceleration scheme has been verified experimentally for the first two stages of the acceleration period by using a beam simulator signal. The results will be presented here and the perspectives of this technique will be discussed