Abstract
Long length vacuum insulated lines are used to carry flowing liquid nitrogen in several high temperature superconducting cable projects. An important, but rare, failure scenario is the abrupt or catastrophic loss of the thermal insulating vacuum producing a rapid increase in heat transfer to the liquid nitrogen stream. In this experimental investigation, a vacuum superinsulated 3 inch by 5 inch NPS (88.9 mm by 141.3 mm) flexible cryostat is subjected to an abrupt loss of vacuum in order to measure the thermal response of a flowing liquid nitrogen stream and the temperature response of the cryostat. The measured outlet stream temperature has a slight peak shortly after the loss of vacuum incident and decreases as the cryostat warms up. The heat loads measured before and after the vacuum loss event are reported. Measurements of the temperatures in the multi-layer superinsulation are also discussed.
