1. N.J. DiNardo, J.E. Demuth, W.A. Thompson, and P.G. Ledermann, Rev. Sci. Instrum. 55, 1492 (1984).
2. Custom as well as standard heaters are available from Spectra-Mat, Inc., 100 Westgate Drive, Watsonville, CA 95076. The version used here has W/Re alloy wires embedded in an alumina matrix and housed in a Mo can.
3. Aquadag is a colloidal graphite paint, which can be brushed onto a surface and then outgassed by bakeout. It provides lubrication and is electrically conductive. Obtain Dag 154 from Ache-son Colloids, 1607 Washington Avenue, P.O. Drawer 611747, Port Huron, MI 48061–1747.
4. G.S. Chottiner, W.D. Jennings, and K.I. Pandya, J. Vac. Sci. Technol. A5, 2970 (1987).
5. R. Raval, M.A. Harrison, D.A. King and G. Caine, J. Vac. Sci. Technol. A9, 345 (1991).