Vacuum System
The vacuum system is composed of two pumps- a foreline and main pump. The foreline pump is a 3 CFM two-stage rotary vane pump from Harbor Freight, with a 22.5 micron vacuum rating. This pump includes R134A and R12/R22 inlets. This brass inlet assembly was removed and replaced with a 3/8” male BSP to KF16 flange adapter, sealed with Hysol 1C vacuum epoxy.
The KF16 forepump flange goes to a KF16 10” stainless steel flexible hose. Copper scouring pad material is stuffed into the forepump end of the hose to act as a condensate/oil trap. The hose connects to a K16 elbow, which is connected to a KF16 tee. The tee extends to a VAT KF16 valve. The other side of the valve connects to the KF16 outlet of the diffusion pump. This valve is used to isolate the roughing pump from the diffusion pump as needed. A Granville-Phillips 275 vacuum gauge is attached to the other tee output, and is used for rough vacuum measurements.
The main pump is an Edwards SI 100 diffusion pump. Dow Corning 704 silicon pump oil is used. The pump is powered by a custom system that supplies 12VDC (for the inlet-baffle Peltier cooler), 120V AC (for the fan), and a variable 90-120VAC (for the pump heater). A variac is used for the variable AC voltage.
The pump inlet is an ISO-F 100 type. An ISO100 to ISO63 flange, with KF25 side port attaches to the pump inlet. The ISO63 output of the flange is blanked off, while the KF25 side port is used as the main vacuum output. An 11” stainless steel KF25 vacuum hose connects this port to the chamber. Briskheat silicone heat tape is used for vacuum bakeouts as needed.
Two vacuum gauges are located on chamber ports. A Granville-Phillips 354 (through a KF25 to KF16 adapter) is used for high vacuum measurements (below 10e-4 torr). An MKS 901P loadlock pressure transducer is used for rough and medium vacuum measurements on the output side of the diffusion pump.
The KF16 forepump flange goes to a KF16 10” stainless steel flexible hose. Copper scouring pad material is stuffed into the forepump end of the hose to act as a condensate/oil trap. The hose connects to a K16 elbow, which is connected to a KF16 tee. The tee extends to a VAT KF16 valve. The other side of the valve connects to the KF16 outlet of the diffusion pump. This valve is used to isolate the roughing pump from the diffusion pump as needed. A Granville-Phillips 275 vacuum gauge is attached to the other tee output, and is used for rough vacuum measurements.
The main pump is an Edwards SI 100 diffusion pump. Dow Corning 704 silicon pump oil is used. The pump is powered by a custom system that supplies 12VDC (for the inlet-baffle Peltier cooler), 120V AC (for the fan), and a variable 90-120VAC (for the pump heater). A variac is used for the variable AC voltage.
The pump inlet is an ISO-F 100 type. An ISO100 to ISO63 flange, with KF25 side port attaches to the pump inlet. The ISO63 output of the flange is blanked off, while the KF25 side port is used as the main vacuum output. An 11” stainless steel KF25 vacuum hose connects this port to the chamber. Briskheat silicone heat tape is used for vacuum bakeouts as needed.
Two vacuum gauges are located on chamber ports. A Granville-Phillips 354 (through a KF25 to KF16 adapter) is used for high vacuum measurements (below 10e-4 torr). An MKS 901P loadlock pressure transducer is used for rough and medium vacuum measurements on the output side of the diffusion pump.