Squid device

摘要

A superconducting quantum interference device for measuring a magnetic field is disclosed which includes a SQUID chip (100) and an energising circuit (Figure 1) for energising the SQUID chip (100). A dewar (200) encloses the SQUID chip (100) and a regulating valve (205) is coupled to the dewar (200) for maintaining the pressure and therefore the temperature within the dewar substantially constant. The regulating valve (205) comprises chambers (212 and 214) separated by a membrane (216). An outlet tube (215) engages the membrane (216) and when pressure rises, the membrane is forced away from the outlet tube (215) to enable gas to escape from the dewar to thereby maintain the pressure constant and the temperature constant within the dewar (200).