H2O PUMPING BY SPUTTER DISCHARGE WITH A LAB6 CATHODE

Properties of H2O water vapor pumping by glow discharge sputtering wit h a LaB6 cold cathode are studied experimentally. For the purpose of d eveloping a new type of sputter ion pump, lanthanum hexaboride (LaB6) is applied as the cathode material on the basis of a preliminary study . The application of LaB6 as the cathode of sputter discharge was prop osed at first to obtain a low outgassing wall for a plasma vacuum cham ber. The experiments showed that the vacuum chamber with the LaB6 sput ter coating reached a lower ultimate pressure than that without the co ating. LaB6 coating by glow discharge on a stainless steel wall is eff ective to reduce the H2O outgassing rate of a vacuum wall as shown by mass spectrometric analysis. The pumping speed of H2O by the coated wa ll is estimated experimentally. Characterization of the LaB6 coated fi lms is also made by x-ray photoelectron spectroscopy measurements. (C) 1996 American Vacuum Society.