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Characterization of a multiple radiation source
Author
Koh, Jong Meng
Supervisor
Lee, Paul Choon Keat
Abstract
The objective of this experimental campaign is to characterize a multiple radiation source. As the soft x-ray emission has been reported in other work, this thesis reports the results and discussions of the neutrons and hard x-ray emitted from a 3.2 kJ Mather type plasma focus (NX2).
The average total neutron yield is measured using an indium foil activation detector at pressure ranging from I to 36 mbar and at various combinations of voltages (8.5 - 14.5 kV), copper anode lengths (2.5 - 6.5 cm) and insulator sleeve length (5.4 - 6.6 cm). A remarkable average maximum neutron yield of (7 ± 1) X 108 neutrons per shot is achieved using a 3.5 cm copper anode with insulator sleeve length of 6.0 cm and operating voltage and pressure of 14.5 kV and 20 mbar respectively. Not only that this is a very good result for a 3.2 kJ device, but the extremely high pressure operating regime at which the optimum production is obtained ensures reproducible results, while preventing the failure of the sensitive components of the high voltage insulation.
The neutron energy, neutron anisotropy and hard x-ray are measured using five scintillator-photomultiplier systems. The average peak neutron energy for the axial direction (Oo), radial direction (90") and backward direction (180") is (2.89 ± 0.25) MeV, (2.49 ± 0.20) MeV and (2.1 1 ? 0.12) MeV respectively. The higher average peak neutron energy of 2.89 MeV in the axial direction can be accounted for by the high energy deuteron ions that are generated and accelerated in the axial direction due to the presence of strong electric fields in the m = 0 instability zone with the stationary deuteron or deuterium target. The average neutron anisotropy, F = - Y ( 0 " ) is found to be (1.46 ± 0.28). The results obtained from neutron energy and anisotropy measurement Y (90 ") suggest that the neutron production mechanism may be predominantly beam target as found by other authors on different machines. The amount and energy of 1 MeV of hard x-ray are also measured and it is found that the average maximum total energy of the x-ray photons is 3 X 10' MeV. The higher neutron yield from the 3.2 kJ machine as compared to the UNU-ICTP Benchmark machine must be due to a more efficient production of high energy deuterons as supported by the fact that higher hard x-ray yield is being obtained.
The average total neutron yield is measured using an indium foil activation detector at pressure ranging from I to 36 mbar and at various combinations of voltages (8.5 - 14.5 kV), copper anode lengths (2.5 - 6.5 cm) and insulator sleeve length (5.4 - 6.6 cm). A remarkable average maximum neutron yield of (7 ± 1) X 108 neutrons per shot is achieved using a 3.5 cm copper anode with insulator sleeve length of 6.0 cm and operating voltage and pressure of 14.5 kV and 20 mbar respectively. Not only that this is a very good result for a 3.2 kJ device, but the extremely high pressure operating regime at which the optimum production is obtained ensures reproducible results, while preventing the failure of the sensitive components of the high voltage insulation.
The neutron energy, neutron anisotropy and hard x-ray are measured using five scintillator-photomultiplier systems. The average peak neutron energy for the axial direction (Oo), radial direction (90") and backward direction (180") is (2.89 ± 0.25) MeV, (2.49 ± 0.20) MeV and (2.1 1 ? 0.12) MeV respectively. The higher average peak neutron energy of 2.89 MeV in the axial direction can be accounted for by the high energy deuteron ions that are generated and accelerated in the axial direction due to the presence of strong electric fields in the m = 0 instability zone with the stationary deuteron or deuterium target. The average neutron anisotropy, F = - Y ( 0 " ) is found to be (1.46 ± 0.28). The results obtained from neutron energy and anisotropy measurement Y (90 ") suggest that the neutron production mechanism may be predominantly beam target as found by other authors on different machines. The amount and energy of 1 MeV of hard x-ray are also measured and it is found that the average maximum total energy of the x-ray photons is 3 X 10' MeV. The higher neutron yield from the 3.2 kJ machine as compared to the UNU-ICTP Benchmark machine must be due to a more efficient production of high energy deuterons as supported by the fact that higher hard x-ray yield is being obtained.
Date Issued
2004
Call Number
QC718.5.D38 Koh
Date Submitted
2004