Speaker
Description
Challenges for accelerator targets and beam intercepting devices show no sign of easing in the coming decades. Unprecedented beam energies and intensities will be put to bear for producing new collider physics and leaps in secondary particle production. Engineers and scientists are being called upon to design, build and operate these vital components to reliably perform as expected. In many cases, new technologies and engineering techniques need to be developed and validated. For pulsed-beam applications the transient effects can be difficult to confidently simulate, particularly when innovative designs or novel materials are necessary to meet design goals, or when protective components are expected to experience permanent damage or phase change. In-beam testing is vital for these situations.
The Spallation Neutron Source mercury target is a first-of-a-kind design: MW-class, liquid metal and short-pulse. In-beam testing was conducted to characterize several aspects of pulse response behavior from the R&D project phase and well into facility operation. The target vessel’s response from a µs beam pulse needed to be understood to validate the design for the desired giga-cycle fatigue life. The pressure wave induced by the pulsing was determined to cause mercury cavitation which complicates modeling of the fluid-structure interaction. For that, real vessel response data was essential to coming up with a credible simulation method. The pressure wave cavitation also leads to erosion damage of the vessel. As SNS power on target increased, development of techniques to mitigate the erosion and fatigue stress also required in-beam testing.
Suitable facilities for in-beam target testing are uncommon. It was fortunate for the SNS that the Los Alamos National Laboratory offered suitable pulsed beams to experimental areas where mercury target tests could be conducted. A review of SNS target experiments will be presented with parallels to HiRadMat capabilities noted. Key areas of envisioned future needs for the broader target / BID community that HRM will be discussed.
