Conceptual design of a bipolar kicker magnet for the J-PARC-Kamioka Neutrino Project
The Japanese Hadron Facility (J-PARC) includes a ring in which the beam is accelerated from an energy of 3 GeV to 50 GeV. One of the proposed experiments, which require the beam to be extracted from this ring, is a long baseline neutrino oscillation experiment. Space constraints in the lattice of the ring result in a requirement for a novel bipolar combined function kicker that can be used for fast extraction or abort. Magnetic field pulses with a rise time of approximately 1.1/spl mu/s and 4.3/spl mu/s flat top duration are required. One of the stringent design requirements of the extraction system is a flat top ripple of less than /spl plusmn/1%. The proposed kicker system is composed of 6 kicker magnets of 1.5 m length each, powered by pulse forming lines (PFL's). To achieve the required kick angle of /spl plusmn/5.32 mrad a low characteristic impedance has been chosen. This paper discusses several different concepts for the kicker system and presents the results of investigations into options for system impedance, and kicker magnet type including transmission line, lumped inductance and hybrid-transmission line.
A fast and accurate GPU based method on simulating energy deposition for beam-target coupling with granular materials
Abstract The simulation of beam energy transfer and medium dynamics is essential in nuclear studies and designs involving the beam loading on targets. Although the existing methods are relatively mature in simulating the thermohydrodynamics of a solid or liquid target coupled with an energetic beam, they may not be entirely applicable to a complex porous medium such as granular materials with massive discrete elements. In this study, a GPU (Graphics Processing Unit) based discrete energy deposition simulation method is proposed for the thermohydrodynamical simulation of granular flow targets with beam-grain coupling. The results of physical validations show that a significant improvement in accuracy was achieved by our method compared to the equivalent homogenization method which just simplified the granular medium to a whole block. This method provides a more accurate alternative solution to the problem of calculating energy deposition on grains. Although the method is computationally intensive, it can be synchronously executed with the granular dynamics simulation owing to the powerful parallel computing capability of GPUs. Thus, the studies on the dynamical and thermal behaviors of beam-grain coupling can be conducted in a relatively fast and precise way.
Shielding Particle Beams by Thin Conductors
We start with previous results [1] for the longitudinal impedance of a wire cage within a cylindrical pipe and generalise the outer boundary condition to include the case of a conducting pipe and of a ferrite pipe. The results are then interpreted by means of an equivalent circuit which makes self-evident the conditions for effective shielding of the outer wall by a cage of wires or wire stripes.