Contents I. Introduction
The Spallation Neutron Source (SNS) target module is a stainless steel vessel through which mercury is pumped. Neutrons are produced through spallation reactions between the high-energy proton beam and the mercury. During a typical SNS operation, 1 ~ 1.4 MW (average power) proton beam is bunched to ~700 ns pulses at a 60 Hz repetition rate. The peak power of the proton beam reaches 25 GW and the corresponding energy deposition in the SNS mercury target is estimated to be over 6 MJ/m3/pulse. Such a high-intensity proton beam is essential for the generation of the world’s most powerful neutron pulses. Meanwhile, the rapid heating of the mercury from individual proton pulses also induces a large pressure surge in the liquid metal which causes dynamic displacements and stresses to occur in the vessel structure [1]. In particular, the fatigue and cavitation due to pressure waves have a strong impact on the target vessel lifetime [2]–[4]. To fully understand the dynamic response of the target during operation, it is important to experimentally measure the target strain waveform after each proton pulse injection.
