The Key Technologies Of Pulse Beam Line And Neutron Spectra Measurements Of D-T Neutron Generators

There was a strong demand for the high-intensity neutron generator in the research and application of nuclear science, especially for the high-intensity neutron generator with pulse function. The design and construction of a DC/pulse high-intensity neutron generator and the nuclear measurement systems were of great significance for the development of advanced nuclear energy technology and relevant technology. This dissertation’s main works were as follows:(1) the physical design of pulse line of Highly Intensified Neutron Generator (HINEG)(2) the analysis of source neutron of HINEG (3) the neutron spectrum measurement technologies, including time of flight measurement system, Bonner spheres spectrometer and the spectra unfolding methods.The design of the pulse line of HINEG was divided into the beam transport system design and the pulsed system design respectively. In order to guarantee the deuteron beam can be smoothly transport to the target, the beam envelope of pulse line was calculated by the Transport and LEADS program. As to the design of the pulsed system, which was critical equipment for realizing nanosecond pulses, used the analytical formulas and experience to complete the preliminary design of the chopper and buncher. Then followed by detailed calculations conducted by numerical simulation and LMOVE codes and design was optimized based on the results of numerical simulation. Using the optimized design, in case the initial bema intensity from ion source was2mA, the spot diameter on the target was4.6-7.4mm, the maximum deuteron intensity on the target was over164u A, and the FWHM(full width at half maximum) of pulse beam on the target was1.26ns. All the parameters were better than designed specifications.Subsequently the source neutron generated by HINEG was analyzed. The source neutron analysis required tritium concentration depth profile in the tritium target, which was under uniform distribution assumption in the previous analysis. The evaluation results showed that this assumption would introduce remarkable error into the source neutron analysis. Then a method based on the alpha spectrum from associated particle method for acquiring the depth profile of tritium in the target was presented, also this method was tested and the test result was consistent with the physical facts. Then the analysis of T(d,n)4He source neutrons of HINEG was finished and increased consideration of D(d,n)3He unexpected neutrons and the parameters of deuteron beam.Finally, the equipment and methods for measuring neutron spectra were studied. For the neutron time of flight measurement system, after the design and the construction of systems, timescale of the channel width, experimental calibration and n-y screening were tested. For the Bonner sphere spectrometers, a design method based on singular value decomposition and information entropy theory was proposed. As to the neutron spectra inverse problem, a multi-model single-output artificial neural network unfolding method was presented, and the test results showed that this method was superior to the maximum entropy method. Also it was found that this method with the unique feature that error of each energy-bin was independent.