High Density Plasma in a High Pressure Hydrogen Capillary Discharge

Summary form only given. Measurements of electron plasma density generated in a hydrogen-filled hollow cathode capillary discharge are reported. The capillary is made of borosilicate glass. H_alpha line and H_beta line stark broadening are used to diagnose the plasma density. A 60 KV peak voltage, 75 ns pulse was applied, which was in excess of the breakdown voltage of the high pressure (>1 atm) hydrogen capillary. Preliminary results indicate that ap10¹⁹ cm^-3 electron density can be obtained. The dependence of the plasma density on the capillary length; the capillary diameter; the gas pressure; the electrode geometry; and the discharge V-I characteristics are presented, and potential applications to plasma wakefield accelerators are also discussed.