Speaker
Description
In a future D-T fusion reactor, neutron diagnostic will be one of the key diagnostics because the neutron has information for the birth profile of alpha particles, fuel ion density ratio, and fuel ion temperature if the plasma is Maxwellian. Diamond detectors are very promising candidates for neutron diagnostics in the harsh radiation environment of a fusion reactor because of their high radiation tolerance and compactness. The neutron diagnostic based on a natural diamond was developed and has been used since the 1990s for 14 MeV D-T neutron measurements in large tokamaks, such as TFTR [1], JET [2], and JT-60U [3]. With the development of diamonds produced by chemical vapor deposition, high-quality artificial diamond detectors become available at relatively low cost.
Recently, a novel compact D-T neutron spectrometer based on a single-crystal chemical vapor deposition (sc-CVD) diamond stack (B14 diamond telescope detector, CIVIDEC Instrumentation GmbH) was developed for fusion plasma diagnostic. The detector consists of one thin and two thick sc-CVD diamond sensors. A neutron to proton converter was installed in front of the detector. This neutron spectrometer was designed for the detection of 3 MeV to 17 MeV neutrons. The neutron energy spectrum can be obtained by the energy of the recoiled protons deposited in the diamond sensors using coincidence analysis. The initial measurement of the D-T neutron with this compact neutron spectrometer were performed using the accelerator-based neutron sources OKTAVIAN at Osaka University [4]. For investigating the effects of neutron to proton converter thickness and distance between the converter and the diamond sensors on energy resolution and detection efficiency of the compact D-T neutron spectrometer, a simulation study was performed using Geant4. The results of the simulation study in this novel compact D-T neutron spectrometer based on a sc-CVD diamond stack will be presented.
[1] A. V. Krasilnikov et al., Rev. Sci. Instrum. 68, 553-556 (1997).
[2] A. V. Krasilnikov et al., Nucl. Instrum. Methods Phys. Res. A 476, 500-505 (2002).
[3] M. Isobe et al., Fusion Eng. Des. 34-35, 573-576 (1997).
[4] L. Y. Liao et al., Rev. Sci. Instrum. 95, 073533 (2024).