Stinger closed cycle cryostat ================================= Overview -------- On the measurement manipulators of both endstations, Bloch is using a 'Stinger' closed cycle helium cryostat. A schematic overview of the system is shown below: .. image:: _static/stinger/stinger.png There are two separate He gas loops, shown here as orange and green. The first loop (orange) uses an F70L/H compressor (in the cupboard, lower level) to feed a Gifford-McMahon (GM) cryocooler in the Stinger 'blue can' mounted up on the platform. The GM cooler takes 300psi helium as input, expands it for cooling power then returns low pressure He. It cools two heat exchange surfaces within the blue can as 'output' - a first stage at 20K (16W capacity) and a second stage at approx 4K (1.25W capacity). This helium loop is never vented or refilled. The second, totally isolated He circuit is powered by the HC-4E1 compressor (in the cupboard, upper level). It sends high pressure room temperature helium into the blue can. It is first pre-cooled by returning gas from this same circuit. It then passes through the heat exchangers of the GM cooler, before travelling through the flexible insert and undergoing a final Joule-Thomson (JT) expansion close to the tip of the cryostat insert. Exhaust gas is sent back up the flexible line into the blue can, then returned to the compressor for the cycle to repeat. An important advantage of this configuration is the decoupling of vibrations from the GM cryocooler from the cryostat. The image below illustrates the gas flow within the cryostat: .. image:: _static/stinger/stinger_insert.png :width: 300 :align: center Cold gas flows through the insert, with the JT expansion happening in a capillary inside the end of the insert. In our case this capillary has an inner diameter of about 480\ |mu|\ m. The teflon gasket seal further up the insert is responsible isolating the outlet and return lines. Technical details -------------------------------- ======================= ============ ============ ============= A Branch Manufacturer Part number Serial number ======================= ============ ============ ============= Stinger system Coldedge 9191399-0133 Recirculator compressor Sumitomo HC-4E1 ??? Cryocooler compressor Sumitomo F-70 FN02561 Cryocooler Sumitomo RDE-412D4 38D19058A ======================= ============ ============ ============= ======================= ============ ============ ============= A Branch Manufacturer Part number Serial number ======================= ============ ============ ============= Stinger system Coldedge 9191399-0132 Recirculator compressor Sumitomo HC-4E1 ??? Cryocooler compressor Sumitomo F-70 FN02560 Cryocooler Sumitomo RDE-412D4 38D19059A ======================= ============ ============ ============= ======================== =========== Standard parameters ======================== =========== Manifold pressure 80-100 PSI F70 pressure (idle) 190 PSI F70 pressure (running) 270 PSI HC-4E1 pressure 80-100 PSI He gas flow (cold) 14 L/min He gas flow (warm) 0.7 L/min ======================== =========== We have an inline Omega FMA1824A flowmeter measuring the He return flow from the cryostat. It is N2 calibrated and rated for 0-20L/min. The conversion factor for He flow is 1.45. .. |mu| unicode:: U+03BC .. |deg| unicode:: U+00B0