Study Of Space-resolving Flux Detection Technique

The inertial confinement fusion (ICF) is one of the important methods for solving energy crisis. Based on the central ignition, the indirectly driven ICF is the most hopeful way approaching to controlled fusion, where the research into laser-plasma dignositics is very important. However, the time- and space-resolving detection of X-ray flux inside the hohlraum is an ongoing problem in indirectly driven ICF experiments, which is also the valid method to detect the fiux "felt" by the capsule, and of extreme importance. This research aiming at the difficult problem and applying imaging-selecting method, overcomes such as the targeting bottleneck, develops the time- and space-resolving flux detector (SRFD), conducts experiment researchs, solves the time- and space-resolving flux detection problem and provides a novel and valid diagnostic method for the capsule "feeling" flux. The contents and main results of this dissertation are as follows:(1) The design?assembly and adjustment for the SRFD have been researched. Through the pinhole creating X-ray images of the hohlraum laser entrance hole (LEH) and the defining aperture choosing area to detect flux, we research into the three dimension design for the components of the SRFD and the entire SRFD which include the pinhole-lens component and its four dimensional adjusting mechanism, the adjustable supporting component, the imaging plate, the defining aperture and its two dimensional adjusting mechanism and the flat-response X-ray detector (F-XRD). After the components manufactured, we have assembled and adjusted the SRFD with excellent performance.(2) The targeting technique of SRFD has been researched. Pointing at the weakness of the pinhole method, i.e.,the fact that the visible light passing through the pinhole is too weak for the SRFD to be targeted, and using a annular lens of which the magnification and object distance are almost the same as those of the pinhole imaging, we realize that the lens imaging assists the SRFD in aiming at the target area in real time.The uncertainties in that process have been analysed, and we find they can be neglected.(3)The detection of the X-ray fluxes emitted from the hot laser spot and cooler re-emitting region in hohlraum have been researched. For the first time, we implement the simultaneous measurement using two SRFDs for the respective X-ray fluxes emitted from the laser hot spot and re-emitting area, in a typical hohlraum experiment on SG? prototype laser facility. We have compared the obtained fluxes with the data measured from LEH by F-XRD at different position, and used the area-weighted post-processed method to verify the validity of SRFD experimentally. The experimental observations is reestablished by our two-dimensional hydrodynamic simulations and well understood with the power balance relationship,in which the scalings associated with the albedo of hohlraum wall have been calibrated by the experimental measurements.(4) The new two-dimensional space-resolving flux detection technique has been researched. By using one SRFD, we have conducted two typical hohlraum experiments respectively for targeting and measuring at the Shenguang-? prototype laser facility. The accurate deviation between the pinhole imaging and the annular lens imaging has been defined, the obtaining of which can enhance the experimental efficiency remarkably. On the other hand, distinct differences between the X-ray flux and radiation temperature from a specific area inside the LEH and those from the entire LEH were observed. The differences were theoretically analyzed using the viewfactor model.The SRFD target area is verified to be the re-emitting wall area alone.