Study Of X-ray Radiation Yield Characteristics For Z-Pinch Plasma

Z-pinch implosion was defined as a process that high current pass plasma through along the axes direction (Z direction) of pulse power facilities, producing powerful annular magnetic field, original plasma was compressed to axes by the work of Lorentz force, forming high temperature and high density plasma. There are roughly four phases: at first, there is an explosion phase, in which the initiation of the pulse-power discharge explodes the wires, setting up an initial plasma state for the second, implosion phase. The implosion is driven by J×B forces as the current discharge continues. When the plasma assembles on axis, a third ( thermalization ) phase begins. In this phase, the kinetic energy is converted to thermal energy and the plasma rapidly ionizes to ionization stages that are generally inaccessible during implosion. The emission of an intense kilovolt x-ray pulse commences during this third phase of the dynamics. Finally, plasma collapses without restriction force. This paper mainly discuss the strong x-ray radiation produced in the third phase. We can study implosion characteristic of Z-pinch from three aspects: x-ray radiation yield,dynamics process of implosion,radiation spectrum of X-ray. X-ray radiation yield and it's characteristics reflect many basic information of plasma, such as, the process of plasma coming into being and developing, the uniformity of plasma in the implosion , the distribution property of electron density and temperature and so on. Measuring and diagnosing the Z-pinch imploding plasma X-ray yield, energy spectrum and it's space-time distribution, we can study the forming of plasma shell, dynamics property of implosion, parameter development of plasma, forming and distribution of hot spots, physics of hohlraum, application of radiation and so on. Simultaneity, it can improve our understanding of the physics process of Z-pinch."Dante" spectrograph system is a mainly diagnostic apparatus for the absolute measurement of X-ray, it is constituted of array which contains different filters, plane speculums, X-ray diodes. In the yield detectors of soft x-ray, response time of photoconductive detector (such as GaAs detector), thermoelectricity detector (such as LiTaO₃ LiNb O₃ detector) and vacuum X-ray diode (XRD) are all subnanosecond. The difference is that photoconductive detectors own high-sensitivity (～10^-4A / W), it is commonly used to low-flux measurement of x-ray; thermoelectricity detectors own low-sensitivity (～10^-7A/ W), and their capability of anti-disturbance is lower, their main advantage is that bias voltage power supply is unnecessarily, so they are commonly used to high-flux measurement of X-ray; the sensitivity of X-ray diode between photoconductive detector and thermoelectricity detector, so it can detect high-flux of X-ray (such as in actual Z-pinch experiment) and low-flux of X-ray (such as in detector calibration). X-ray diode also has many other advantages, such as small bulk,quick response,convenience to use and so on. In the Z machine of Sandia National laboratory(SNL) of America, five-channels filter-XRD array is preferred diagnostic equipment for continuous radiation flux of soft X-ray.Based on studying the prevenient research of Z-pinch implosion, we established eight-channels "Dante" spectrograph system, accomplished the design and machining of spectrograph system, calibrated the spectral response of optic element in the Institute of High Energy Physics of Chinese Academy of Sciences, accomplished anti-electromagnetic disturbance experiment of spectrograph detector system, and made use of the spectrograph for Z-pinch implosion experimental research with the loads of gas puffs and arrays on the "Yang" accelerator, and estimated rapidly the power and energy of X-ray by direct numerical methods using the data of XRD channel signals, and also unfolded the energy spectrum by base function expansion method and obtained more exact parameters of experiment are reported in this paper.Finally, the test results and it's analysis of "Dante" spectrograph system, and the result comparision analysis of spectrograph and X-ray scintillator powermeter are reported in this paper.