Lakeshore DESERT1

• Fermer la VALVE 1 entre la turbo et le SAS.
• Fermer la VALVE 2 entre la pompe primaire et le SAS.
• Ouvrir la valve de purge (VENT), attendre jusqu'à la pression atmosphérique.
• Ouvrir le SAS, placer les échantillons.
• Fermer la VALVE 3 entre la pompe primaire et la pompe TURBO.
• Ouvrir la VALVE 2 pour pomper le SAS avec la pompe primaire.
• Lorsque le vide atteint 10 ^-3 TORR, fermer la VALVE 2.
• Ouvrir la VALVE 3 entre la pompe primaire et la TURBO.
• Ouvrir lentememnt la VALVE 1 entre le SAS et la TURBO.
• Bouger le bras de transfert jusqu'à la chambre.
• Bloquer le porte échantillon, ensuite dévisser le bras de transfert et le ramener vers le bas.
• Fermer la VALVE 1.

Prepare the transfer line by placing the compression fitting onto the transfer line shoulder. The compression fitting came installed on the probe station's bayonet and
was removed during assembly.

Close the foot valve, and then open by turning five to six complete turns counter-clockwise.

Slowly insert the transfer line into a Dewar. The required port is a 0.5-inch o-ring compression seal. Lower the leg slowly until the Dewar pressure just starts to rise. Close the low-pressure (typically 0.5 psi) relief valve on the Dewar. Monitor the pressure and be sure to keep it below 6 psi. This can be achieved using a relief valve on the Dewar exhaust or by connecting a regulated helium supply to the Dewar exhaust.

Continue to lower the transfer line slowly enough that the Dewar pressure does not rise dramatically, until the transfer line leg hits the bottom of the Dewar. The Dewar pressure should be approximately 5 psig. The process of precooling the transfer line is complete when a continuous plume of white vapor is ejected from the other end of the transfer line. The time required should have been approximately 5 minutes. Note the size of the white plume to mentally compare it with earlier, successful precools.

Insert the transfer line into the bayonet on the probe station. You may need to wipe ice crystals from the tip of the transfer line before insertion; use a clean cloth for this purpose. Push the transfer line in until it stops, then tighten the outer nut on the compression fitting at the base of the transfer line leg. The transfer is started.
To secure the transfer line in position, insert the clevis pin in the holes in the lower and upper rings. Insert the cotter pin to hold the clevis pin in place. The process is the same for nitrogen, except the transfer line will cause less pressure rise in the Dewar, and an external source of pressure may be needed.

Set the desired temperature on the temperature controller. To continue transfer into the probe station, settings for fast initial cooldown are foot valve fully open (5 to 6 turns open) and Dewar pressure at about 5 psig. Once the probe station is cool, the transfer rate can be reduced. For temperatures below 60 K, it works well to keep the Dewar pressure at 2 to 3 psig and close the foot valve until the desired transfer rate is achieved. The general procedure is to close the foot valve until the cold head temperature starts to rise, and then continue closing the foot valve until the set-point
temperature can be maintained with control heat applied to the cold head. For temperatures above 60 K, the required flow is very small. More efficient long-term transfer is achieved by lowering the Dewar pressure to about 0.5 psig and adjusting the foot valve setting accordingly.