Derivation of Simple Evaluation Method for Thermal Shock Damage on Accelerator Materials Caused by Out-of-control Beam Pulses and its Application to J-PARC

概要

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In high-intensity proton accelerator facilities, a failure of an electromagnet that steers beam pulses may result in thermal shock damage to the accelerator material by injecting an out-of-control pulse. It is important that a Machine Protection System (MPS) is appropriately designed to prevent this damage in the facilities such as the Japan Proton Accelerator Research Complex (J-PARC). In this study, a simple evaluation method for the allowable injection time before the operation of the MPS was derived from the relation between the thermal stress and the yield stress of materials. As the first step in the derivation, the upper limit of heat generation was formulated for various kinds of materials without beam experiments. Second, the allowable injection time was evaluated on the basis of the upper limit of heat generation, assuming a Gaussian distribution in the beam current density. The derived evaluation method was then applied to J-PARC. The allowable injection time ranged from 1.5 to 330 μs for the incident energy above 25 MeV. This time was longer than the beam pulse width for the 3-GeV RCS ring, and some beam-transport lines. On the other hand, the injection of the whole pulse was not permitted for the other accelerating systems of J-PARC.
一般社団法人日本原子力学会の論文
2005-12-25