%0 Journal Article
%T Effect of Wall Material on H每 Production in a Plasma Sputter-Type Ion Source
%A H. J. Ramos
%A J. R. S. Lazarte
%A Y. D. M. Ponce
%J -
%D 2004
%X The effect of wall material on negative hydrogen ion (H每) production was investigated in a multicusp plasma sputter-type ion source (PSTIS). Steady-state cesium-seeded hydrogen plasma was generated by a tungsten filament, while H每 was produced through surface production using a molybdenum sputter target. Plasma parameters and H每 yields were determined from Langmuir probe and Faraday cup measurements, respectively. At an input hydrogen pressure of 1.2 mTorr and optimum plasma discharge parameters Vd = 每90 V and Id = 每2.25 A, the plasma parameters ne was highest and T每e was lowest as determined from Langmuir probe measurements. At these conditions, aluminum generates the highest ion current density of 0.01697 mA/cm2, which is 64% more than the 0.01085 mA/cm2 that stainless steel produces. The yield of copper, meanwhile, falls between the two materials at 0.01164 mA/cm2. The beam is maximum at Vt = 每125 V. Focusing is achieved at VL = 每70 V for stainless steel, Vt = 每60 V for aluminum, and Vt = 每50 V for copper. The results demonstrate that proper selection of wall material can greatly enhance the H每 production of the PSTIS
%U http://journals.upd.edu.ph/index.php/sciencediliman/article/view/106