Dynamic strain and pressure measurements of a mercury target under thermal shock tests

A mercury target will be used to produce neutrons from pulsed 1-GeV protons for the Spallation Neutron Source (SNS). Mercury was selected because of its high source brightness, its low freezing temperature, and the improved radiation damage lifetime expected. The mercury target vessel will be made of thin stainless steel walls. One of the key issues associated with using such a target is the ability to withstand the thermal shock loads caused by the pulsed proton beam of 17,000 J in {approximately}0.5 {micro}s. The resulting pressure waves in the mercury associated with the enormous rate of temperature rise ({approximately}10{sup 7} C/s), will interact with the walls of the mercury target. This interaction could lead to excessive stresses in the target vessel, thereby limiting the lifetime of the target. To address the thermal shock issues, a series of single-pulse tests on a mercury target was conducted in the Los Alamos Neutron Science Center (LANSCE). Additional single-pulse thermal shock tests were conducted in the LANSCE facility on January 30--31, 1999.