This paper presents the two methods enabling to determine distributions of electron density and/or electron temperature of the plasma sheath originating in plasma-focus phenomenon. These methods are based on theoretical considerations and processing of experimental results taken by means of high-speed frame photography in narrow band of visible spectrum and multi-frame laser interferometry. Both high-speed photography subsystems can operate simultaneously with sub nanosecond accuracy and allow recording frame sequence of plasma with temporal resolution of about 1 ns and spatial resolution of about 0.1 mm. They are also equipped with digital readout. The detailed explanations and considerations concerning presented methods are exemplified by results obtained in experimental investigations.
This paper presents the multi-frame image-capturing system based on a few simultaneously operating high-speed photography subsystems, capable of acquiring plasma images in different parts of radiation spectra, i.e. in a visible as well as soft X-ray spectral range. The passive optical diagnostic subsystem allows recording frame sequence and streak images of plasma in visible spectrum. It consists of the streak camera and the high-speed four-frame camera. The high-speed four-frame camera is based on of the first generation image intensifiers and is able to acquire images of plasma originating in plasma-focus phenomena with minimal estimated optical gate time of about 1 ns. The two cameras based on an open microchannel plate devices allow recording four-frame plasma images in a soft X-ray range with estimated X-ray gate time of about 2 ns. All presented high-speed photography subsystems are equipped with digital readout. Some examples of the results obtained by means of the multi-frame image-capturing system, are given in the final part of the paper.
This paper presents the construction details of the multi-frame optical cameras and the gating pulse generating system applied to the dynamic supplying of the first generation image intensifiers. Presented cameras are equipped with digital readout and are able to acquire multi-frame images of investigated object with minimal estimated optical gate time of about 1 ns. The special method and suitable experimental arrangement are proposed in order to determine an actual optical gate time of the gated image intensifiers. Some examples of the results obtained by means of the multi-frame optical cameras, are given in the final part of the paper.
This paper presents the construction details of the X-ray frame cameras and the gating pulse generating systems applied to the dynamic supplying of open microchannel plate-based devices. Presented cameras are equipped with digital readout and are able to acquire one-frame or four-frame images of plasma originating in plasma-focus phenomena with minimal estimated X-ray gate time of about 800 ps. Some examples of the results obtained by means of the nanosecond X-ray frame cameras, are given in the final part of the paper.
The efficiency and threshold of ablation of polymethylmethacrylate (PMMA), polytetrafluoroethylene (PTFE), and monocrystalline silicon by single pulses of soft x-rays emitted from Z-pinch, plasma-focus, and laser-produced plasmas were investigated. The Z-pinch was driven by the S-300 pulsed-power machine (Kurchatov Institute, Moscow) and the plasma focus was realized in the PF-1000 machine (Institute of Plasma Physics and Laser Microfusion, Warsaw). Higher temperature plasma than with the discharge plasmas was obtained by focusing the near-infrared beam from the PALS high-power iodine laser system (Czech Academy of Sciences, Prague) on the surface of a metallic slab target. The role of nonthermal processes in x-ray ablation was evaluated. Possible ways to use x-ray ablation for micromachining are discussed.
A high-power all-Nd:glass laser using fiberless chirped-pulse- amplification technique is presented. The laser is capable of producing 1.2-ps, 2-TW pulses while the effective divergence of the beam does not exceed 10-4 rad.
The new design of three-frame interferometer is proposed. The optical system of the interferometer, though very simple, has some advantages in comparison with classical interferometers (e.g., Mach-Zehnder interferometer). For registration and analysis of interferograms the CCD cameras and multichannel image acquisition system are used. The interferometer has been tested in a laser-matter experiment. Some results of plasma investigation are presented.
Systems for optical diagnostics of plasma created in a plasma-focus device are described, showing progress in the development and application of different optical methods used in plasma-focus research. In the experiments carried out on the plasma-focus device at the Institute of Plasma Physics and Laser Microfusion, multiframe Iser interferometry and shadow photography, the Faraday rotation method, and high-speed photography in different spectral ranges were applied. The system used for investigation of the plasma structure and dynamics is fully automatic and is able to acquire images on 10 channels with time resolution of about 1 ns and spatial resolution of about 0.1 mm. Subnanosecond synchronization between different diagnostics was achieved. Some examples of recently obtained results are given.