Wide-aperture plasma-electrode pockels cell
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WideAperture PlasmaElectrode Pockels Cell N. F. Andreeva, A. A. Babina, V. S. Davydova, A. Z. Matveeva, S. G. Garaninb, Yu. V. Dolgopolovb, S. M. Kulikovb, S. A. Sukharevb, and S. V. Tyutinb a
Institute of Applied Physics, Russian Academy of Sciences, ul. Ulyanova 46, Nizhni Novgorod, 603950 Russia b AllRussian Federal Nuclear Center (VNIIEF), pr. Mira 37, Sarov, 607188 Russia Received September 20, 2010
Abstract—The results of experimental investigations of wideaperture (100 × 100 mm) plasmaelectrode Pockels are presented. Time characteristics, contrast, transmission factor, and optical uniformity of the cell are measured. It has been found that the halfwave effective voltage of the cell is 10 kV, the duration of the transmission window can vary from 250 to 550 ns, its leading and trailing edges are 40–50 and 70–100 ns in duration, respectively, and the time of the cell plasma electrode formation is 40 ± 5 ns. DOI: 10.1134/S1063780X1106002X
INTRODUCTION In the laser facilities developed at present and intended for inertial fusion confinement (ICF), high energies of generated laser beams are achieved by using wideaperture amplifier modules operating in a fourpass mode. Isolation of amplifier modules from one another and from the radiation scattered at the objects sub jected to radiation is one of the fundamental problems faced during laser experiments. The isolation elements allow avoiding uncontrolled selfexcitation of high power amplification cascades of the facility and make it possible to generate laser radiation with the required characteristics. In particular, isolation in the Luch facility [1] is accomplished with the help of a specially developed scheme of a reverser equipped with the Pockels switch that starts transmitting laser radiation only at the moment of the arrival of the laser pulse amplified after the first and the second pass. Thus, the fourpass amplification circuit is subdivided into two doublepass ones that prevents its selfexcitation. At present, neodymiumdoped glass lasers are designed using the Pockels cells made of potassium dihydrogen phosphate crystals KDP (KH2PO4) or a corresponding deuterated compound, namely, DKDP. The results of the development and investigation of characteristics of the Pockels cell with a 70 mm aper ture fabricated in a traditional way (ring electrodes on a cylindrical crystal surface) are presented in [2]. In a cell with such a design, the required uniformity of the electric fields inside a crystal is achieved if L > 1.3D (where L and D are the crystal length and diameter, respectively). Fabrication of the Pockels cells with the diameter D > 100 mm using traditional methods necessitates growing crystals with the length L > 130 mm that substantially increases their cost. In this case, the quality of the crystals is often not very high,
which tells on characteristics of the switch, in particu lar, on its contrast and transmission factor. For this difficulty to be avoided, the concept of the plasmaelectrode Pockels cell (PEPC) was
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