Wenfa Huang

Sapphire face cooling for high-repetition-rate terawatt-class Ti:sapphire amplifier

In this work, we evaluated the feasibility of sapphire conductive cooling for short-pulse Ti:Sapphire (Ti:sa) laser amplifiers which suffers from thermal issues under high-repetition-rate and high-energy operation. Numerical heat transfer simulations of 100-TW class sapphire face-cooled Ti:sa gain modules operated around 300 W average powers are presented. The distributions of temperature, stress, strain, and birefringence in liquid cooled sapphire/Ti:sa/sapphire assembly are calculated by a finite element analysis. Based on these data, the thermal induced wave front distortions and depolarization are investigated for different repetition rates. We determine that sapphire face cooling concept holds a promise of achieving higher energies and repetition-rates in Ti:Sa amplifiers.

Research and control of thermal effect in a helium gas-cooled multislab Nd:glass laser amplifier

As the development of the laser-driven technology, the next generation of laser-driven device sets higher requirement for the repetition frequency. The higher repetition gives rise to thermal deposition, which induces thermo-optical effect, elasto-optical effect and bulk displacement. The thermal efficient management is an important approach to dissolve the thermal deposition. The quasi uniform distribution of heat medium is realized by helium cooling Nd:glass slab and the control of edge temperature. In the case, wavefront distortion and depolarization losses is obtained in experiment. Results said that both of them are improved greatly. At the same time, the distribution of temperature, stress and strain and stress birefringence in Nd:glass are analyzed by using finite element numerical simulation method. And the calculation results show that the wavefront distortion and depolarization losses match with the experimental results very well.

LD pumped cryogenic-cooled Yb:YAG disk regenerative amplif ier

A diode-pumped cryogenic-cooled Yb:YAG regenerative amplifier based on the thin disk concept, producing 14.2-mJ, 10-ns pulses with optical-to-optical conversion efficiency of ~7% at a repetition rate of 10 Hz at 163 K, is presented.

Optimum Analysis on Solid Dielectric Insulation Dimension in the Coaxial Electrodes Under Nanosecond Pulse Voltage

The majority of radial electric field declining in the very close vicinity of inner electrode results in very much non-uniform distribution of coaxial radial electric field in coaxial electrodes. Under the circumstance of invariable inner electrode diameter, increasing the diameter of outer electrode, the radial electric field decrease, following a stage of rapid decay, is markedly slowed down after the gap between the inner and outer electrodes is longer than a threshold; the same is only increasing the diameter of inner electrode as well as accordingly increasing the diameter of outer electrode, a given gap between inner and outer electrodes. After the inner electrode diameter passes a threshold because of the slight increment of diameter of inner electrode, the radial electric field also first decreases fast a very short stage, then evidently shows a flat process. The appearance of two thresholds about two parameters, the interval between inner and outer electrodes and the diameter of inner electrode, implies the optimum conception of the coaxial insulation structure of pulsed power equipments. This paper provides the empirical formula relevant to flashover length and the inner electrode diameter on the basis of the results of ANSYS software and experiments, the experimental results is of flashover data of polymethyl methacrylate(PMMA) and nylon 1010 in transformer oil under coaxial electric field under the applied pulsed voltage in the range of nanosecond.