Z-pinch experiments with two arrays consisting, respectively, of 32 4-μm- and 6-μm-diameter tungsten wires have been carried out on QiangGuang-1 facility with a current rising up to 1.5 MA in 80 ns. At early time of...Z-pinch experiments with two arrays consisting, respectively, of 32 4-μm- and 6-μm-diameter tungsten wires have been carried out on QiangGuang-1 facility with a current rising up to 1.5 MA in 80 ns. At early time of implosion, x-ray framing images show that the initial emission comes from the central part of arrays, and double clear emission rings, drifting to the anode and the cathode at 5×10^6 cm/s and 2.4×10^7 cm/s respectively, are often produced near the electrodes. Later, in a 4-μm-diameter tungsten wire array, filamentation caused by ohmic heating is prominent, and more than ten filaments have been observed. A radial inward shift of arrays starts at about 30 ns earlier than the occurrence of the x-ray peak power for both kinds of arrays, and the shrinkage rate of emission region is as high as 1.7×107 cm/s in a 4-μm-diameter tungsten wire array, which is two times higher than that in a 6-μm one. Emission from precursor plasmas is observed in implosion of 6-μm-diameter tungsten wire arrays, but not in implosion of a 4- μm-diameter tungsten wire array. Whereas, in a 4-μm-diameter tungsten wire array, the soft x-ray emission shows the growth of m=l instability in the plasma column, which is caused by current. The reasons for the discrepancy between implosions of 4-μm- and 6-μm-diameter tungsten wire arrays are explained.展开更多
The fabrication and absolute calibration of a B-dot probe is employed to measure the pulsed magnetic field at the Shenguang-Ⅱhigh power laser facility.Copper enameled silk with a cross section diameter of 0.1 mm is u...The fabrication and absolute calibration of a B-dot probe is employed to measure the pulsed magnetic field at the Shenguang-Ⅱhigh power laser facility.Copper enameled silk with a cross section diameter of 0.1 mm is used to wind the one-turn coil with a 1 mm diameter.Two coils are paired and reversely linked to their respective circuits to form a differential B-dot probe that is sealed in and protected by a quartz shell.This B-dot probe is experimentally calibrated and then used to measure the pulsed magnetic field in laser targeting experiments at the Shenguang-Ⅱhigh power laser facility.Signals show a high performance of this B-dot probe.The common mode noise can be effectively canceled out by the differential pair.The magnetic field of over 300 T can be extrapolated at the location close to the target.展开更多
Spatially-resolved crystal spectrometers with a high spectral resolution are developed to diagnose K-shell x-ray radiation from Z-pinch plasmas. These diagnostic apparatuses are successfully applied to aluminum wire a...Spatially-resolved crystal spectrometers with a high spectral resolution are developed to diagnose K-shell x-ray radiation from Z-pinch plasmas. These diagnostic apparatuses are successfully applied to aluminum wire array Z-pinch experiments on QiangGuang-I facility, a driver with a pulsed current up to about 1.5 MA in 80 ns. Time-integrated experimental results show that the K-shell x-ray emission lines of aluminum Z-pinch plasmas are dominated by line emissions from helium-like ionisation state. Bright spots that might have higher electron temperature or density are produced randomly in location and size along the z-axis during implosions. According to the experimental data, the electron temperature and the ion density are estimated to be between 250 eV and 310 eV, and between 7.0× 10^19 cm-3 and 4.0 ×10^19 cm-3 respectively, while the ion temperature is inferred to be about 10.2 keV, which is much higher than the electron temperature.展开更多
基金Project supported by the National Natural Science Foundation of China （Grant No 10035030）.
文摘Z-pinch experiments with two arrays consisting, respectively, of 32 4-μm- and 6-μm-diameter tungsten wires have been carried out on QiangGuang-1 facility with a current rising up to 1.5 MA in 80 ns. At early time of implosion, x-ray framing images show that the initial emission comes from the central part of arrays, and double clear emission rings, drifting to the anode and the cathode at 5×10^6 cm/s and 2.4×10^7 cm/s respectively, are often produced near the electrodes. Later, in a 4-μm-diameter tungsten wire array, filamentation caused by ohmic heating is prominent, and more than ten filaments have been observed. A radial inward shift of arrays starts at about 30 ns earlier than the occurrence of the x-ray peak power for both kinds of arrays, and the shrinkage rate of emission region is as high as 1.7×107 cm/s in a 4-μm-diameter tungsten wire array, which is two times higher than that in a 6-μm one. Emission from precursor plasmas is observed in implosion of 6-μm-diameter tungsten wire arrays, but not in implosion of a 4- μm-diameter tungsten wire array. Whereas, in a 4-μm-diameter tungsten wire array, the soft x-ray emission shows the growth of m=l instability in the plasma column, which is caused by current. The reasons for the discrepancy between implosions of 4-μm- and 6-μm-diameter tungsten wire arrays are explained.
基金This work was supported by National Natural Science Foundation of China(Nos.11435011,11775204,11505170,11405160,11305160)。
文摘The fabrication and absolute calibration of a B-dot probe is employed to measure the pulsed magnetic field at the Shenguang-Ⅱhigh power laser facility.Copper enameled silk with a cross section diameter of 0.1 mm is used to wind the one-turn coil with a 1 mm diameter.Two coils are paired and reversely linked to their respective circuits to form a differential B-dot probe that is sealed in and protected by a quartz shell.This B-dot probe is experimentally calibrated and then used to measure the pulsed magnetic field in laser targeting experiments at the Shenguang-Ⅱhigh power laser facility.Signals show a high performance of this B-dot probe.The common mode noise can be effectively canceled out by the differential pair.The magnetic field of over 300 T can be extrapolated at the location close to the target.
基金supported by the National Natural Science Foundation of China (Grant No. 10635050)
文摘Spatially-resolved crystal spectrometers with a high spectral resolution are developed to diagnose K-shell x-ray radiation from Z-pinch plasmas. These diagnostic apparatuses are successfully applied to aluminum wire array Z-pinch experiments on QiangGuang-I facility, a driver with a pulsed current up to about 1.5 MA in 80 ns. Time-integrated experimental results show that the K-shell x-ray emission lines of aluminum Z-pinch plasmas are dominated by line emissions from helium-like ionisation state. Bright spots that might have higher electron temperature or density are produced randomly in location and size along the z-axis during implosions. According to the experimental data, the electron temperature and the ion density are estimated to be between 250 eV and 310 eV, and between 7.0× 10^19 cm-3 and 4.0 ×10^19 cm-3 respectively, while the ion temperature is inferred to be about 10.2 keV, which is much higher than the electron temperature.
