Large Array Ntof Spectrometer Measurement And Control System Prototype Development

In the late 1980s the ICF (inertial confinement fusion), driven by high-power laser, had been as one of high-tech research development themes, aimed at researching on advanced laser strategic defense technology and the use of laser technology to develop research and technology operation of ICF. ICF is a highly complex, multidisciplinary research field, and the research work of ICF has been very important on the national economy, military applications, and exploration of basic subjects.Nuclear fusion reaction products in ICF can be used to study characteristics of its plasma. Because not only nuclear reaction products are produced during the combustion time, but also produced in the combustion area of fuel pill. Nuclear diagnostics can be used to measure many of the properties of implosion process, such as neutron yield, ion temperature, fuel areal density〈ρR〉, etc. Comparing with other diagnostics technologies, nuclear diagnostics will be less disturbed.The ultimate objective of ICF is to achieve controllable thermonuclear fusion, and one of the most important symbols is the production of nuclear fusion-neutron. Ion temperature and fuel areal density 〈ρR〉 are two important parameters, which can be used to diagnose whether fusion reaction occurs in the interior of target pill. During the fusion, the energy of primary neutron is simplex(the neutron energy of the DD fuel response is 2.45 MeV; and 14.1 MeV of DT fuel response)with the Doppler broadening , which is due to the center-of-mass velocity of reacting ion pairs and is characterized by the ion temperature for a Maxwellian distribution of ions with zero collective velocity. So Ion temperatures achieved in ICF targets are often determined by measuring the energy spectrum of the primary fusion neutrons, and fuel areal density is determined by measuring the energy spectrum of the secondary fusion neutrons.It is a quite difficult to get neutron spectrum directly. The conventional method is to determine the energy of detected neutrons through their flight time, because the ICF target nucleus can be approximately regarded as the point source in the space, and detected neutrons can be regarded to appear at the neutron interactions in a scintillator. These detectors are useful for neutron yields above 10¹⁰, but are limited at lower yields. This way has already become the only way in ICF experiment now.Conventional current-mode neutron TOF detectors can measure the time history of the total light output from many ite emission time of the scintillator, the finite response time of the detector, and the statistics of neutron scattering and light production in the scintillator.Single-neutron-interaction detector arrays are used to increase sensitivity while maintaining good time resolution for low-yield targets.The system measure the neutron arrival time distribution using an array of 960 scintillator-photomultiplier detectors, each of which has about 1 ns time resolution and is operated in the single-hit mode. The arrival time distribution is constructed from the results of 100 or more detector measurements. Compared to Conventional current-mode neutron TOF detectors, Single-neutron-interaction detector arrays have many detectors and a large area of effective detectors, which guarantee its good time resolution for low-yield targets. Now the large neutron scintillator array has one of the standard ICF diagnostics technologies.The large neutron scintillator array now researching for "ShenGuang 3" prototype has 1 ns time resolution. Its electronics system prototype uses leading edge timing discriminators and direct Time-Digital-Convert, with "Amplitude-Time-Walk" correction method. The entire electronics system prototype is composed of Amplifier Timing Discriminator Module (ATD), Time-Digital-Convert Module (TDC), Amplitude-Digital-Convert Module (ADC), Control Module, Fan-out Module etc.In order to provide enough redundant to the detector system, time resolution of electronics system prototype is defined to 100ps, and resolution of Time-Digital-Convert Module (TDC) is 65ps.After a series of electronics test, the Time-Digital-Convert Module and the entire electronics system prototype are proved to meet the requirement and the Control Module works well. Afterwards the detector system has been connected. Using cosmic rays we test the system's "Amplitude-Time-Walk" correction, which prove its final time resolution has met the requirement of the large neutron detector array.Most key characters in this thesis are listed as follows:(1) Preparing for the first large neutron scintillator array in domestic ICF equipment, we have developed the Time-Digital-Convert Module (TDC) and the Control Module in electronics system prototype.(2) Using the new "Time-Digital-Convert" chips in the multi-channel time measurement for ICF experiment. The chip uses internal propagation delays of signals through gates to measure time intervals with very high precision and its calibration function guarantees good channel uniformity.