C. E. Zheng

Performance of a ten-liter electron avalanche-discharge XeCl laser device

This paper describes the laser performance of an X-ray preionized ten-liter volume, electron-avalanche discharge XeCl system, operated at dc charging voltages of up to 70 kV both with and without X-ray preionization. An output energy of more than 11J uniformly distributed over a (7×10) cm2 spot size was achieved using a multichannel spark-gap as the main discharge switch. The discharge was also successfully operated in the switchless mode, yielding a 4.8 J output energy and a 0.9% efficiency. The time-resolved gain measurements provided information on the laser discharge evolution.

Compact three-electrodes excimer laser IANUS for a POPA optical system

A novel discharge configuration has been realized with the XeCl laser IANUS, which has been developed at the ENEA Frascati center as a 1:1 laser head prototype for the 1 kW average output power XeCl system EOLUS (EUREKA EU211 Project). The patented design of the discharge region consists of two active zones which are geometrically in parallel and electrically in series. The obvious advantages of this configuration are, the presence of the intermediate high impedance electrode, suitable for prepulse application, then the absence of current return bars, so improving the recirculating gas flow uniformity, and the automatic synchronization of the two discharges very useful for a compact oscillator-amplifier configuration (POPA). A number of measurements have been done on IANUS, to have an almost complete characterization; based on these results a generalized self-filtering unstable resonator (GSFUR) has been designed and realized on the smaller gap, leaving the other active medium for the high optical quality beam amplification, in the scheme of a POPA system. The GSFUR output beam results are 1.5 times the diffraction limit, with an energy of 9 mJ in a 87 ns FWHM pulse.

Magnetic pulse compressor for prepulse discharge in spiker‐sustainer excitation technique for XeCl lasers

A high‐voltage pulse output modulator using a step‐up transformer with two stages of magnetic pulse compression circuits has been developed as a spiker for the purpose of obtaining the breakdown of the gas mixture when using the spiker‐sustainer excitation technique for pumping XeCl discharge lasers. When the transformer input is fed by a current pulse with a peak value and a full width of 1.16 kA and 1.6 μs, respectively, formed by a discharge of an initially charged 19‐kV, 57‐nF capacitance in series in the transformer primary loop, the 2.7‐nF output capacitor bank (Cp) of the spiker can be charged up to 67 kV with a (10%–90%) rise time of 59 ns. The modulator has been tested at a repetition rate of up to 600 Hz in burst mode using a resistor in parallel with Cp as the load.

Self-filtering unstable resonator operation of XeCl excimer laser

A diffraction-limited laser beam with a pulse energy of 120 mJ and brightness up to a magnitude order of 1014W . cm-2. Sr-1has been achieved in an X-ray preionized discharge XeCl laser by using a self-filtering unstable resonator. The near- and far-field laser properties have been examined.

Self-filtering unstable resonator: An approximate analytical model with comparison to computed and XeCl laser experimental results

Abstract Approximate analytical solutions for the lowest-order transverse mode of empty self-filtering unstable resonator have been deduced for magnification M 》 1, and compared with some experimental measurements on an X-ray preionized XeCl discharge laser.

Excimer lamp pumped by a triggered longitudinal discharge

The ultraviolet (UV) radiation performance of an XeCl excimer lamp is measured as a function of the gas mixture composition (with and without neon as buffer gas) and pumping condition (longitudinal discharge with and without trigger). Both spatial distribution and spectral content of the emitted UV radiations are carefully determined including the contribution of the XeCl (B-X), XeCl (C-A), and Xe continuum emissions. A peak power density of up to 3 kW/cm/sup 2/ and an average power density of up to 0.2 W/cm/sup 2/ can be achieved when using a simple cylindrical aluminum reflector.

Space and time resolved discharge evolution of a large volume X-ray triggered XeCl laser system

The spatial distribution and the temporal development of the net gain have been measured in a ten liter active volume switchless discharge XeCl laser. The experimental results are compared with both zero-dimensional and two-dimensional kinetic code predictions. The comparison between the results of the kinetic codes and of some measurements relevant to the time-dependent discharge homogeneity allows a deeper insight into the influence of the streamer evolution on the discharge characteristics.

Large area X-ray preionizer for electric discharge lasers

A pulsed X-ray source with a pulse duration of 250 ns (FWHM) which uses plasma cathodes to supply sufficient electrons for emission is described. It is simple to construct and requires low energy input. Less than 14 J of energy can produce up to 107 electron-ion pairs/cm3 in a 10l volume of neon at 1 atm.

Some design limitations for large-aperture high-energy per pulse excimer lasers

SummarySome limitation problems for gas discharge excimer lasers, when scaled to a high pulsed energy output with high repetition rate are discussed. As an example, we present some experimental results obtained with an X-ray preionized (10×10×100) cm3 active volume, low-repetition-rate-operated gas discharge XeCl laser system.

Parametric study of an x‐ray preionizer with plasma cathode

The construction characteristics and the performances of an x‐ray diode working at 200 Hz are described. The temporal behavior of both the plasma cathode emission and the diode discharge has been studied, including the measurements of vacuum effects on the repetition rate and lifetime capability, preionization versus electrical features, and ionization density versus dosage. This simple and low‐cost x‐ray diode has been used to uniformly preionize a half‐liter XeCl laser, delivering an output laser energy of 800 mJ/shot at a 100 Hz repetition rate.