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1.
To investigate the imploding characteristics of cylindrical wire array, experiments with load current varying from 1.5MA to 1.7MA were carried out on the Qiangguang-1 facility. The complicated temporal-spatial distribution of x-ray radiation was measured by the one-dimensional (1D) x-ray imaging system. Other diagnostic equipments including the x-ray power meter (XRPM) and the time-integrated pinhole camera were used to record time-resolved x-ray power pulse and pinhole x-ray images. Analysis shows that the fast leading edge of the local x-ray radiation pulse is of primary importance in sharpening x-ray power pulse rather than the temporal synchrony and the spatial uniformity of implosion. Experimental results indicated that the better axial imploding synchrony, the faster the increase of x-ray power for an array consisting of 32 tungsten wires of 5 μm diameter than for the others, and the higher the x-ray radiation power with maximal convergence ratio (r0/r1) of 10.5. A ‘zipper-like' effect of x-ray radiation extending from the anode to the cathode was also observed.  相似文献   

2.
A time-resolved multispectral X-ray imaging approach with new version of multi-channel Kirkpatrick- Baez (KB) microscope is developed for laser plasma diagnostics at the kilo joule-class Shenguang-II laser facility (SG-II). The microscope uses a total external reflection mirror in the sagittal direction and an array of multilayer mirrors in the tangential direction to obtain multiple individual high-resolution, high- throughput, and quasi-monochromatic X-ray images. The time evolution of the imploded target in multiple X-ray energy bands can be acquired when coupled with an X-ray streak camera. The experimental result of the time-resolved 2.5 and 3.0 keV dual-spectral self-emission imaging of the undoped CH shell target on SG-II is given.  相似文献   

3.
<正>Two curved crystal spectrometers are set up on the "QiangGuang-1" generator to measure the z-pinch plasma spectra emitted from planar aluminum wire array loads.Kodak Biomax-MS film and an IRD AXUVHS5# array are employed to record time-integrated and time-resolved free-bound radiation,respectively.The photon energy recorded by each detector is ascertained by using the L-shell lines of molybdenum plasma.Based on the exponential relation between the continuum power and photon energies,the aluminum plasma electron temperatures are measured.For the time-integrated diagnosis,several "bright spots" indicate electron temperatures between(450 eV~520 eV)±35%.And for the time-resolved ones,the result shows that the electron temperature reaches about 800 eV±30%at peak power. The system satisfies the demand of z-pinch plasma electron temperature diagnosis on a~1 MA facility.  相似文献   

4.
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 1.5MA in 80ns. 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 5×106cm/s and 2.4×107cm/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 1.7×107cm/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=1 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.  相似文献   

5.
The plasma window is an advanced apparatus that can work as the interface between a vacuum and a high pressure region. It can be used in many applications that need atmosphere-vacuum interface, such as a gas target, electron beam welding, synchrotron radiation and a spallation neutron source. A test bench of the plasma window is constructed in Peking University. A series of experiments and the corresponding parameter measurements have been presented in this article. The experiment result indicates the feasibility of such a facility acting as an interface between a vacuum and a high pressure region.  相似文献   

6.
雷耀虎  刘鑫  郭金川  赵志刚  牛憨笨 《中国物理 B》2011,20(4):42901-042901
In order to push the grating-based phase contrast imaging system to be used in hospital and laboratories,this paper designs and develops a novel structure of x-ray scintillator functioning also as an analyser grating,which has been proposed for grating-based x-ray differential phase contrast imaging. According to this design,the scintillator should have a periodical structure in one dimension with the pitch equaling the period of self-image of the phase grating at the Talbot distance,where one half of the pitch is pixellated and is made of x-ray sensitive fluorescent material,such as CsI(Tl),and the remaining part of the pitch is made of x-ray insensitive material,such as silicon. To realize the design,a deep pore array with a high aspect ratio and specially designed grating pattern are successfully manufactured on 5 inch silicon wafer by the photo-assisted electrochemical etching method. The related other problems,such as oxidation-caused geometrical distortion,the filling of CsI(Tl) into deep pores and the removal of inside bubbles,have been overcome. Its pixel size,depth and grating pitch are 3 μm×7.5 μm,150 μm and 3 μm,respectively. The microstructure of the scintillator has been examined microscopically and macroscopically by scanning electron microscope and x-ray resolution chart testing,respectively. The preliminary measurements have shown that the proposed scintillator,also functioning as an analyser grating,has been successfully designed and developed.  相似文献   

7.
A code has been developed for calculating the non-coronal radiation of impurity in a compound plasma system which consists of high and low temperature regions. The radiation loss of impurity carbon in this system is calculated and analysed. The cooling rate in this system is smaller than that in a homogeneous plasma system due to the particle exchange between the two regions of the system. The volumetric radiation is much bigger in the low temperature region than in the high temperature region because of the relatively low temperature and high electron density, despite the much smaller volume.  相似文献   

8.
A long-range sound propagation experiment was conducted in the West Pacific Ocean in summer 2013.The signals received by a towed array indicate that the travel speed of pulse peak(TSPP)in the convergence zones is stable.Therefore,an equivalent sound speed can be used at all ranges in the convergence zones.A fast calculation method based on the beam-displace-ment ray-mode(BDRM)theory and convergence zone theory is proposed to calculate this equivalent sound speed.The computation speed of this proposed method is over 1000 times faster than that of the conventional calculation method based on the normal mode theory,with the computation error less than 0.4%compared with the experimental result.Also,the effect of frequency and sound speed profile on the TSPP is studied with the conventional and fast calculation methods,showing that the TSPP is almost independent of the frequency and sound speed profile in the ocean surface layer.  相似文献   

9.
The sound field distribution of a broadband array is calculated using the acoustics FEM and BEM.The FEM-BEM model is established for a nine-element plane array and its numerical method of calculating mutual radiation impedance among the transducers is given. The changing law of mutual radiation impedance influencing acoustics performances is analyzed. The directivity and beam width of the plane array are calculated at three resonance frequencies.A broadband dense plane array with nine elements is developed using triply resonant transducers.The input impedance and directivity of the plane array are measured in anechoic water tank.Results show that it is reasonable to design the array according to the half wavelengh of the first resonance frequency of the array element.The numerical solution agrees with the measuring results well,which indicates the FEM-BEM method is feasible to calculate sound field distribution and analyze mutual impedances.  相似文献   

10.
The behaviours of ionization and shock propagation in radiatively heated material is crucial for the understanding of indirect drive inertial confinement fusion as well as some astrophysics phenomena. In this work, radiation field with a peak temperature of up to 155 eV was generated in a gold cavity heated by four laser beams on the SG-II laser system and was used to irradiate a plastic foam cylinder at one end. The radiatively ablated foam cylinder was then backlighted side-on by x-ray from a laser-irradiated Ti disk. By observing the transmission decrease due to the shock compression of the foam cylinder, the trajectories of shock front were measured, and from the onset of the intense thermal emission from the side of the cylinder, the propagations of the ionization front were also observed on the same shot. The experimental measurements were compared to predictions of the radiation hydrodynamics code Multi-1D and reasonable agreements were found.  相似文献   

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