Magnetic Proton Recoil Spectrometer Magnetic Simulation And Experimental Study Of The Analysis System

Spectrum of neutrons produced in fusion reactions contains key parameters like ion temperature and fuel density in center part of plasma. High-performanced diagnostic technologies of pulsed neutron spectrum are important for fusion research. A widely used instrument in intense pulsed radiation field is the time-of-flight proton recoil spectrometer. However, flight distance of DT neutrons (～14MeV) is hardly available because of space limitation and neutron yield in some special experimental conditions.Magnetic proton recoil (MPR) spectrometer is a recently-appeared instrument to measure spectrum of low-yileded DT neutron at close distance, which can be used to accurately determine ion temperature and fuel density. The main aim of this thesis is to research the MPR technology. Magnetic analyzing system of a compact MPR spectrometer is designed and experimentally researched.The magnetic analyzing system achieves "point-to-point" focus in the horizontal plane by homogeneous magnet field and fringing fields.The system is studied with the optics of charged particle beams and computer software. Parameters of beam transport are calculated and design of the system is proposed. Based on the design and calculations, an applicable beam transport simulation program is founded, and main performances of the system are researched. Considering the transport parameters obtained from theoretical calculation and simulation, experiment system for practical conditions is designed.The C-shaped NdFeB permanent dipole with a pole gap of 3 cm produces a homogeneous field of 0.792 Tesla. Measurement shows that average intensity and fringing field of the dipole meet the requirements of the magnetic system. Simulations of charged particle beams with measured magnet field data show that protons with energy between 4MeV and 8MeV can be momentum analyzed with consistent resolution. Maximal incident solid angle of the system is about 1.2ms and the resolution is estimated to be better than 3% under appropriate settings of diaphragm dimension.Experimental investigations are conducted with a 239Puαsource and CR-39 detectors to test performances of the system. Position distributions of a beams with different energies are measured under different settings of diaphragm dimension and detector position. The results show that tracks of a beams are accordant with theoretical calculations and simulations. Resolution of the system is about 2% andαparticles with energy of 5.15MeV and 5.47MeV can be distinguished.Geometrical seetings and corresponding capabilities of the MPR spectrometer are studied according to performances of the magnetic analyzing system. Spectrum of neutrons with energy between 8MeV and 16MeV can be mearsured by the spectrometer. For collimated 14MeV neutrons, the detection efficiency is expected to be 0.85×10-8 with an energy resolution of about 4.5%.