We believe it is important for users to understand the baseline performance for their particular system, so we provide a Certificate of Performance on each system that is shipped. Every assembled system goes through multiple cooldown and warmup cycles at the factory to ensure all core functions are operating as expected.Primary use: for cryogenic thermal connections
Where to purchase: SPI Supplies
Primary use: for lubricating vacuum O-rings
Where to purchase: SPI Supplies
Primary use: for wires or samples within the 4 K space
VGE must cure before pulling vacuum or cooling down the system! VGE takes approximately 24 hours to cure under ambient conditions, or 30 minutes at 60°C using an oven or heat lamp.
VGE joints should be inspected periodically (approximately every 6-12 months) as it can flake off after several thermal cycles. VGE only has a shelf life of one year, so be sure to replace any extra VGE annually.
Where to purchase: LakeShore
The sample chamber utilizes O-rings to maintain a high vacuum environment. If the O-ring seal is compromised it can cause a vacuum leak in the system. O-rings should be regularly inspected, cleaned, and greased for optimal performance. The exposed surface should be wiped with a dry Kimwipe or lens tissue and re-greased with a thin layer of L-grease (just enough so the surface is shiny) every 10-15 uses. Before every cooldown, or if a leak occurs, inspect the O-rings to ensure they are free from debris and other contaminates.
To protect O-rings, avoid setting them directly on any surface. When not on the sample chamber, the upper vacuum housing should be set on a flattened corner if it is not equipped with protruding bosses that protect the O-rings. Always wear sterile gloves to avoid contaminating surfaces.
O-rings rarely need to be replaced unless they are nicked or damaged. If damaged, use Teflon-tipped tweezers or your fingers to remove the O-ring. Do NOT use metal-tipped tweezers or other sharp objects as this could damage the aluminum housing.
The system uses Viton O-rings as they have been shown to outgas the least under standard operating conditions.
All lower housing side panels also have an O-ring interface. Do NOT remove side panels before consulting with an authorized service representative.
The vacuum control unit provides an inlet for dry nitrogen gas. Although dry nitrogen is optional, it is highly recommended, especially in humid environments. While nitrogen is not used to assist in the cooling of the system, it does help to optimize vacuum levels and keep the system clean and dry.
Nitrogen is used during the following procedures:
Nitrogen purge cycles help to rid the system of contaminants by repeatedly filling the vacuum space with dry nitrogen and then pumping out the gas. The nitrogen molecules are first pumped into the sample space where they adhere to moisture/water vapor and other contaminants. The molecules are then evacuated out of the sample space and into the roughing pump during the purge portion of the cycle. Nitrogen purge cycles can decrease the initial pump-down time and improve vacuum levels. Nitrogen purges also help to clean the charcoal absorbers that trap molecules during cryo-pumping.
The nitrogen source can either be high or ultra-high purity. The port on the back of the vacuum control unit fits a ¼ inch tube. When open, the vent valve allows 10 psi of dry nitrogen to flow into the sample space. If less than 10 psi of nitrogen is flowing through the port, the software will not detect the presence of nitrogen, but the nitrogen will still flow into the sample space at the lower pressure.
Nitrogen should always be used in a few instances: