Design Of Gas-puff Load And Experiments Studies On Z-Pinch Plasma

Considering as one of possible intense soft x-rays radiated sources from z-pinch plasma for realizing controlled thermonuclear fusion, Z-pinch plasma is being intensively studied in the world at present.This dissertation stresses the experiments studies on soft x-ray, plasma diagnostics and radiation characteristics. We have completed two items of work: (1) designing a gas-puff load system used in z-pinch and measuring the capability and flow Simulation; (2) gas-puff z-pinch experiments were carried out on the accelerator "Yang", used some diagnostic devices such as x-ray nanosecond frame-camera, x-ray power system, PIN diode array, a time-resolved x-ray pinhole camera, streak camera, x-ray multi-channel power system, differential laser interferometry for studying the soft x-ray energy and power radiated and the implosion process from z-pinch plasma. This work was supported by the National Science Foundatin of China No. 10035030.The results of experiments of gas-puff load system used in z-pinch are shown below:(1) The experimental results of the system of gas-puff load used in Z-pinch indicated: it has an advantage of stability and repetitive operations. The results of utilizing the program of flow field to simulated line mass density and flow distribution are shown below: the line mass density of gas-puff load is about 13 μg /cm~2, the flow distribution is consistent with the image of initialization plasma obtained in gas-puff z-pinch experiments.(2) In gas-puff Z-pinch experiments, the peak values of the soft Xray pulse energy and power measured with soft x-ray power system is above 800J, 12GW with pulse widths (FWHM) about 20ns and the X ray images in every phase of imploding plasma progresses are attained. And the results are shown below: the spatial distribution of initial gas has a significant influence on the course of gas-puff Z-pinch. Uniformity of the gas-puff distribution initially induces that early load electric current through the main channels of plasma layer are non-symmetrically; the flow distribution of "trumpet" shape induces "zipper" effect of plasma from cathode to anode, the flow distribution of "neck constringency" induces plasma "neck constringency" effect, early collapse and disperse of pinch plasma on anode; along z-axis, "zipper" effect of plasma is obvious and the velocity is up to 2.89xlO7 cm/s;the implode speed under "trumpet" distribution is differrent along z-axis, up to 4.4x107 cm/s at the largest radius; the instability mostly happens in mid-anaphase of pinch, and m=0 of fast increasing is dominant, m=l instability and R-T instability take second places; the cathode produces high-temperature metal plasma after plasma disperses in the anaphase of pinch, and the temperature of the cathode is always higher than that of the anode during pinch; at the same time, it is observed that when the rise time of the load driven current is shortened, pinch speeds of plasma increase enormously, the temperature of cathode and anode is consistent quickly and the influence of plasma instability is reduced.At present, the system of gas-puff load has been used in Z-pinch experiments successfully. It provides an experimental condition to study the principle of the Z-pinch physics, and establish a favorable basis for domestic researches on Z-pinch physical phenomenons and ICF.