Molecular drag pump

A molecular drag pump is a type of vacuum pump that utilizes the drag of air molecules against a rotating surface.[1] The most common sub-type is the Holweck pump, which contains a rotating cylinder with spiral grooves which direct the gas from the high vacuum side of the pump to the low vacuum side of the pump.[2] The older Gaede pump design is similar, but is much less common due to disadvantages in pumping speed.[3] In general, molecular drag pumps are more efficient for heavy gasses, so the lighter gasses (hydrogen, deuterium, helium) will make up the majority of the residual gasses left after running a molecular drag pump.[4]

The turbomolecular pump invented in the 1950s, is a more advanced version based on similar operation, and a Holweck pump is often used as the backing pump for it. The Holweck pump can produce a vacuum as low as 1×10−8 mmHg (1.3×10−6 Pa).

  1. ^ Duval, P.; Raynaud, A.; Saulgeot, C. (1988). "The molecular drag pump: Principle, characteristics, and applications". Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films. 6 (3). American Vacuum Society: 1187–1191. Bibcode:1988JVSTA...6.1187D. doi:10.1116/1.575674. ISSN 0734-2101.
  2. ^ Naris, Steryios; Koutandou, Eirini; Valougeorgis, Dimitris (2012). "Design and optimization of a Holweck pump via linear kinetic theory". Journal of Physics: Conference Series. 362 (1): 012024. Bibcode:2012JPhCS.362a2024N. doi:10.1088/1742-6596/362/1/012024. ISSN 1742-6596.
  3. ^ Conrad, A; Ganschow, O (1993). "Comparison of Holweck- and Gaede-pumping stages". Vacuum. 44 (5–7). Elsevier BV: 681–684. Bibcode:1993Vacuu..44..681C. doi:10.1016/0042-207x(93)90123-r. ISSN 0042-207X.
  4. ^ A. Bhatti, J; K. Aijazi, M; Q. Khan, A (2001). "Design characteristics of molecular drag pumps". Vacuum. 60 (1–2). Elsevier BV: 213–219. Bibcode:2001Vacuu..60..213A. doi:10.1016/s0042-207x(00)00374-2. ISSN 0042-207X.