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On the basis of the conformal characteristics of a logarithmic spiral crystal in a large field of view(FOV),a new type of transmission crystal analyzer used for X-ray monochromatic imaging was investigated.Compared with a reflection type of crystal analyzer,the logarithmic spiral crystal analyzer has a wider FOV for catching the monochromatic X-ray image and a simple space arrangement for achieving the same magnification.According to the diffraction theory of the crystal and the surface equation of log spiral,the imaging principles and characteristics of the transmission type logarithmic spiral crystal analyzer were researched,including the magnifications in horizontal and vertical directions as well as the FOV sizes.A logarithmic spiral analyzer with a quartz crystal was developed.Then with the proposed analyzer,the monochromatic backlighting experiment for the mesh grid with a diameter of 100 μm was carried out by taking an X-ray source of Cu target as the backlighter.The experimental results show that the FOVs of the transmission type logarithmic spiral crystal analyzer are 15.938 7 mm and 5.900 6 mm in horizontal and vertical directions,respectively.Furthermore,the spatial resolution of the analyzer is at least 30 μm under a source diameter of 110 μm.

An efficient total-variation-diminishing radiation magnetohydrodynamics code FOI-1a has been developed. Calculations with FOI have been performed with in the parameters range of Yang accelerator and PTS facility. Numerical results demonstrate that for light array the radiation at peak is dominated by shock heating, while for massive array by shock heating together with adiabatic compression. The ratio of shock heating to adiabatic compression decreases with increasing of array mass. Precursor plasma produced by ablation weakens shock heating and hence has a negative effect on peak radiation. However, precursor plasma has another stabilization effect on magnetic-Rayleigh-Taylor instability, so there should be an optimum ablation rate that maximizes the peak radiation.

A transmission grating spectrometer has been fabricated for the study of X-ray radiations from Z-pinch plasma. The spectrometer contains a 3 333 lp/mm gold transmission grating and an X-ray CCD to record time-integral spectral images. Two slits are employed in the spectrometer. One is used for 1D space resolving and the other, working together with the grating’s entrance slit, can collimate the incident X-rays and thus improve the spectral resolution of the spectrometer. The spectrometer has been used in Z-pinch experiments performed on Yang accelerator. When using Al wire arrays as Z-pinch loads, the Al K-shell lines and lines from Li-like ions were observed. In addition, by comparing the spectral image with the image obtained from an X-ray pinhole camera, the K-shell radiations emitted

The measurement of charge separation potentials of metal targets irradiated by 107 W/cm2, 30 ns X-ray pulses produced by Z pinch on “Yang” accelerator (1 MA, 80 ns) shows kilovolt target potentials existing for 40 ns. The pinch load was tungsten wire array (3 mm in radius) consisting of 16 wires with a radius of 5 μm. The measurement also gives the distribution of potentials on the targets. The polarity of the potential indicates that the electrons move along target surfaces, not along the normal direction. The experimental results show that thermoelectric effect is the main mechanism causing this charge separation. The conclusions reveal that, electrons’ individual behavior including photoelectric effect and Compton effect dominates when targets are irradiated by

The interfacial RT instability experiments on imploding jelly liners in cylindrically convergent geometry have been performed. The liner's instability growth was observed clearly with a high-speed framing camera. Jelly liners have different initial perturbation forms on their inner and outer interfaces, being either smooth or sinusoidal. The initial perturbations also have different magnitudes and spatial frequencies (for example, mode n=5, 10, 20). The experimental results show that the growth and coupling of perturbations on inner and outer surfaces are remarkably different. Meanwhile, the relevant 2-D numerical simulation of hydrodynamics combined with Level Set method has been performed. Using the numerical code, we can design the parameters of imploding jelly liner and predict the experimental results. The results of simulation are demonstrated to be in good agreement with the measured data in a series of experiments.

The interfacial RT instability experiments on imploding jelly liners in cylindrically convergent geometry have been performed. The liner's instability growth was observed clearly with a high-speed framing camera. Jelly liners had different initial perturbation forms on their inner and outer interfaces, smooth one or sinusoidal one. The initial perturbations also had different magnitude and spatial frequency (for example, mode n=5, 10, 20). The experimental results show that the growth and coupling of perturbations on inner and outer surface are remarkably different. Meanwhile, the relevant 2D numerical simulation of hydrodynamics combined with Level Set method has been performed.

In this paper, we represent the radiation characteristics of electromagnetic pulse generated by Z pinch implosion. Magnetic energy which couples with motions of metallic wire arrays or solid liners driven by Z pinch can radiate away. Theoretical results indicate that the radiation power of electromagnetic pulse is determined by both load current and implosion trace. Experiments are carried on primary test stand facility at Institute of Fluid Physics where a current rising to 7 MA in (10%–90%) 65 ns is used to drive a wire array Z pinch. The measured load current and implosion trace show that the Z pinch can deliver about 1 GW, 10 ns full width, 20–70 MHz central frequency, broadband electromagnetic pulse with an energy conversion efficiency of 10-7. Parameters of electromagnetic pulse are much smaller than those of X-ray with a power of 50 TW and an energy of 0.5 MJ. In the approximation of weak relativistic case, the power of electromagnetic pulse which is proportional to sixth power of load current, dramatically increases with current increasing. Soft X-ray radiation is an important channel for dissipating a considerable fraction of energy provided by facility. The results presented here demonstrate that electromagnetic pulse emission in the case of higher load current can cause significant damage to diagnostic devices. Moreover, intense electromagnetic pulse produced by this method may have many potential applications.

The X-ray radiation properties of titanium wire X-pinch are investigated on the Yang accelerator at 500800 kA peak current with a rise time of about 80 ns. The radiation power, spectrum and source size of the X-pinch X-ray source are measured and analyzed using X-ray diodes, a transmission grating spectrometer, a crystal spectrometer and a slit camera. The hot dense spot smaller than 15 m emits 1 J of X-ray with an FWHM of 200 ps and a peak power of 1.5 GW distributed in the range of 14 keV. A method to efficiently generate a single X-ray pulse during the X-pinch implosion is demonstrated. The X-pinch presented here is useful for imaging the early stage interior structure of Z pinch as a backlight source.

In this paper, the principle of the collisional-radiative model for the estimation of plasma parameters from the ratios of K-shell spectral lines was introduced. The structure of a computer program, ZSPEC, developed for the analysis of K-shell line spectra emitted by Z-pinch plasma based on the collisioanl-radiative model was described in detail. The calculation for neon plasma were presented, including the number fractions of major ionization stages at different electron temperature and the contours of K-shell line ratios in the plane defined by electron density and electron temperature. ZSPEC had been used to analyze the measured results of neon gas-puff Z-pinch experiment performed on Yang accelerator. By comparing the K-shell line ratios of neon plasma obtained by an elliptical crystal spectrometer with the results calculated by ZSPEC, the time and space averaged electron temperature and electron density of the K-shell plasma for the shot with 540 kA peaking current were determined to be 240 eV and 1.0×1019 cm-3, respectively.

Single-shell gas-puff Z-pinch experiments were performed on “Yang” accelerator （peak current 500—850 kA， rise time ～85 ns）. The x-ray power and yield， the time-resolved and time-integrated images of plasma implosions were measured. Based on the corresponding diagnostics， the implosion time was defined and the implosion process was divided into four stages. the initial plasma status and the distribution of radiative intensity were studied. In addition， the implosion trajectories， load mass， radial convergence and magneto- Rayleigh-Taylor （MRT） instability were analyzed.

A preliminary experiment for studying the argon-puff Z-pinch implosion process has been performed on the Yang accelerator. The ten-frame nanosecond temporal and spatial gated camera，visible high-speed scanning camera, differential laser interferometer, X-ray time integration pinhole camera and X-ray power system have been used to investigate the evolution of the argon-puff Z-pinch. Some typical results of argon-puff Z-pinch during implosion and pinch phase, including the “zipper” effect, necking phenomenon, sausage instability，temperature changes and the effect of load current rise time, are given and analyzed as examples, and some relevant conclusions are drawn.