Simple analytic expressions are derived to design uniform-field electrodes that are superior in compactness and field uniformity to those described in literature. When such electrodes are used in a TEA laser system, smaller electrodes can be used for the same gas-discharge width.
A novel excitation technique is described for molecular gas lasers. A specially constructed electrode configuration is activated by a rapid Marx generator. A very homogeneous selfsustained discharge can be obtained although no separate preionization source is present. The construction is applied to a CO2 system. Details of the operating characteristics are given. We found the maximum energy production to be over 60 J per liter and a small-signal gain of 6% per cm could be reached.
In this letter the photoemissive properties of K-Te films produced under ultrahigh vacuum conditions are reported. K-Te photocathodes were fabricated by vapor deposition of Te and K onto a Mo substrate into the preparation chamber of the Free Electron Laser of the University of Twente. The highest quantum efficiency obtained at 259 nm was 11.1%, measured just after evaporation; this value decreased in a few minutes to a stable quantum efficiency of 8.3%. The reported results show that K-Te can be considered a promising material for the use as a photocathode in photoinjectors.
Experiments have been performed on a corona preionization type 10 cm aperture TEA CO2 laser. For a CO2 : N2 : He = 1 : 1 : 7 mixture an output energy of 34 joule per liter and for a 1 : 1 : 10 mixture 40 joule per liter could be obtained. The overall efficiency is about 18%. The time behaviour of the current and voltage of the system shows a delay of several hundreds of nanoseconds after the preionization peak, which indicates a relatively low initial electron-density level. Neverthe less, it proved to be high enough to obtain a very homogeneous discharge and reproducible output energy.
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