A turbomolecular pump (TMP) is a multi-stage axial‑flow turbine in which high speed rotating blades provide compression by increasing the probability of gas molecules moving in the pumping direction. The turbomolecular pump is optimised for molecular flow conditions and requires a suitably sized two stage rotary vane pump or an oil free scroll pump to exhaust to atmosphere.
A compound molecular pump (CMP) is based on the concept of combining bladed turbomolecular stages with molecular drag stages on the same rotor. This design allows:
• High critical foreline pressures (typically up to 10 mbar)
• Options to use smaller backing pumps or dry diaphragm backing pumps
Peak pumping speed N2
Peak pumping speed Ar
Peak pumping speed He
Peak pumping speed H2
Maximum backing pressure N2
l/s
l/s
l/s
l/s
mbar
EXT75DX
42
39
49
48
8
nEXT85
47
44
61
49
18
nEXT240
240
230
230
165
9.5
nEXT300
300
280
340
280
9.5
nEXT400
400
380
390
325
9.5
A turbomolecular pump (TMP) is a multi-stage axial‑flow turbine in which high speed rotating blades provide compression by increasing the probability of gas molecules moving in the pumping direction. The turbomolecular pump is optimised for molecular flow conditions and requires a suitably sized two stage rotary vane pump or an oil free scroll pump to exhaust to atmosphere.
A compound molecular pump (CMP) is based on the concept of combining bladed turbomolecular stages with molecular drag stages on the same rotor. This design allows:
• High critical foreline pressures (typically up to 10 mbar)
• Options to use smaller backing pumps or dry diaphragm backing pumps