Large Vacuum Test Facility (LVTF) at the Plasmadynamics and Electric Propulsion Laboratory

The centerpiece of the Plasmadynamics and Electric Propulsion Laboratory (PEPL) at the University of Michigan is the Large Vacuum Test Facility (LVTF) that was built in the early 1960s by the Bendix corporation and was later donated to the university in 1982. This cylindrical stainless-steel clad tank, which is 9 m long and 6 m in diameter, is the largest vacuum facility of its kind at any university in the nation. The chamber is evacuated by two 2,000 cfm blowers and four 400 cfm mechanical pumps to moderate vacuum (30 - 100 mTorr). To reach high-vacuum (10^-7 Torr), the chamber employs seven CVI TM-1200 nude cryopumps, with a combined pumping speed of 500,000 l/s on air, and 240,000 l/s on xenon.

For propulsion systems which primarily use hydrogen (e.g., electrothermal engines), the facility is supported by six 81-cm-diameter diffusion pumps (with water-cooled coldtraps) backed by the two blowers and four mechanical pumps described above. These pumps give the facility an overall pumping speed of over 300,000 l/s on hydrogen at 10^-4 Torr.

Read about the origins of the LVTF in the Jan-Feb 1961 issue of Bendix Orbit, a company newsletter from the Bendix corporation. In 1961, the facility reportedly cost $10M USD. In 2002 dollars, this is roughly equivalent to $60M USD.

Schematic of the LVTF
The main vacuum chamber at PEPL. The 9-m-long by 6-m-diameter chamber is supported by an array of cryopumps, giving it a pumping speed in excess of 500,00 l/s on nitrogen and 240,000 l/s on xenon.