An intense and efficient source of vacuum ultraviolet radiation: low-pressure Xe Townsend discharge

An intense vacuum ultraviolet spike 0.2 μs in width is observed at the initial stage of low-pressure Xe discharge, i.e., Xe Townsend discharge, in submillimeter tubes. The intensity of the 147 nm resonance line reaches 1.3 W/cm2, about 200 times stronger than that obtained from the steady-state Xe positive column. Efficiency of the vacuum ultraviolet radiation exceeds 24%, or 32 lm/ W when green phosphor is excited, four times higher than that of the positive column, or more than an order of magnitude higher than that of the negative glow. This high intensity and efficiency originate from the optimized electron energy which can be adjusted externally by changing the electric field and pressure, contrary to that in the positive column or negative glow. Another important feature of the Townsend discharge is its wide dynamic range of operation, which is advantageous when driving a panel having a large number of cells with scattered discharge characteristics. Consequently, a gas discharge display panel utilizing the Townsend discharge has more than an order of magnitude higher efficiency than the positive column or negative glow panels.