Hot vs. Cold Ionization Gauges: Which One is Best for Me?

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Hot vs. Cold Ionization Gauges3IntroductionEvery modern high vacuum and ultrahigh vacuum system relies on some form ofionization gauge for pressure measurements under 10 -3 Torr. There are currently twocompeting ionization gauge technologies to choose from which are viable means forpressure measurements between 10 -2 and 10 -10 Torr:1. In the hot cathode gauge (HCG) ionizing electrons from a thermionic cathode areaccelerated by suitable electrodes into an ionizing space.2. In the cold cathode gauge (CCG) ionization is caused by a circulating electronplasma trapped in crossed electric and magnetic fields.In both cases, the electrical current resulting from the collection of the positive ionscreated inside the gauge is used as an indirect measure of gas density and pressure.This application note is designed to help vacuum users choose between the twocompeting ionization technologies. Each gauge type has its own advantages anddisadvantages. The best choice requires careful consideration of the operatingcharacteristics of both gauges and is dependent on the application.For more detailed information on this subject consult the following publications:1. J. M. Lafferty, Ed., "Foundations of Vacuum Science and Technology", p. 414,section 6.9., John Wiley and Sons, NY, 1998. Note: This is an excellent bookrecommended for any high vacuum question.2. R. N. Peacock, N. T. Preacock, and D. S. Hauschulz, "Comparison of hot cathodeand cold cathode ionization gauges", J. Vac. Sci. Technol. A 9(3) (1991) 1977.3. R. F. Kendall, "Cold cathode gauges for ultrahigh vacuum measurements", J. Vac.Sci. Technol. A 15(3) (1997) 740.4. R. F. Kendall, "Ionization Gauge Errors at Low Pressures", J. Vac. Sci. Technol. A17(4) (1999) 2041. Note: Great paper that compares the performance of both gauges,particularly at low pressures.5. Vic. Comello, "Should your next ion gauge run hot or cold?", R&D Magazine, p. 65,Nov. 1997.6. Eric Bopp, "Pressure measurement in ion implanters", Solid State Technology,February 2000, p. 51. Note: The special gauging requirements of ion implantapplications are nicely discussed in this article.7. J. H. Singleton, "Practical Guide to the use of Bayard-Alpert Ionization Gauges",J. Vac. Sci. Technol. A 19(4) (2001) 1712.IGC100 Ion Gauge Controller
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