Actually, almost all the JJ arrays use liquid helium for cooling. High temp superconductors make for very poor JJ arrays due to grain boundary effects. The Russians had some limited success with LN cooled arrays. ------------are a number of items that require calibration before you can even start the liquid nitrogen flowing. _________________________________________________________________ Windows 7: It works the way you want. Learn more. http://www.microsoft.com/Windows/windows-7/default.aspx?ocid=PID24727::T:WLMTAGL:ON:WL:en-US:WWL_WIN_evergreen:112009v2