Stress Waves due to Deposited Heat in Mercury and Lead Spallation Targets

Stress waves resulting from deposited heat in mercury and lead spallation targets were studied. A computation was carried out with the following conditions: —the incident proton energy and current are 1.5 GeV and 3.3 mA, respectively: the total proton energy is 5 MW in short pulses at a frequency of 50 Hz —targets are mercury and lead —proton beam profile has a Gaussian distribution. The following results are obtained: 1. It is found that the cylindrical part of the container expands due to stress waves with periods of 180 μs for mercury and 130 μs for lead. The periods are roughly evaluated by D/V, where D is the diameter of target container, 0.2 m, and V the speed of sound in fluid materials. 2. Membrane components of stress control large amplitude stress waves, whilst bending stress components induce high frequency stress waves in both targets. 3. A fitting function describing deposited energy as, a function of position in the target was proposed. The ratio of deposited energy to the projectile energy is under 50% for 1.5 GeV protons for both targets.