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Optimization of neutron yield in a 20kj plasma focus device
Author
Hashim Mohd Shariff
Supervisor
Lee, Paul Choon Keat
Abstract
The results of experiments carried out on a newly developed dense plasma focus device NX-3 that has recently been made operational at Plasma Radiation Source Lab, NIE, Nanyang Technological University, Singapore is reported. The 20kJ pulsed power system of NX-3 plasma focus device comprises of eight modules (of ~2.5kJ each) and cumulatively delivers peak current of 600kA in a quarter time period of less than 3.5 µs. The major objective of preliminary phase of experiments was to investigate the neutron yield performance of this device using 6 different anode designs at various deuterium filling gas pressures. The diagnostics used during these experiments are: 3He detector for the neutron yield measurements and Rogowski coil for di/dt, current measurements.
During the investigation, it was discovered that the safe operating voltage was at 14.2kV thus making the device operate at 10kJ. The average neutron yield has been found to be in the order of 109 neutrons/pulse in 4πsr for the deuterium filling gas pressure range of 0.2 mbar to 10 mbar. Both the time integrated and time resolved techniques are employed to study the neutron emissions from this novel device. Using the first anode design (A20Z160)), maximum neutron yields has been found to be 2.38 × 109 neutrons/pulse for the pressure of 6 mbar. In using second anode design (A26Z160), it has been found that the peak neutron yield was 2.54 × 109 neutrons/pulse for the pressure of 5 mbar. In the third anode design (A55Z160), maximum neutron yield has been found to be 1.04 × 108 neutrons/pulse for the pressure of 0.25 mbar. In the fourth anode design (A20Z140), maximum neutron yield has been found to be 1.4 × 109 neutrons/pulse for the pressure of 6 mbar. In the fifth anode design (A26Z140), maximum neutron yield has been found to be 3.4 x 109 neutrons/pulse for the pressure of 6 mbar. Finally in the sixth anode design (A55Z70), maximum neutron yield has been found to be 1.1 × 109 neutrons/pulse for the pressure of 0.6 mbar.
During the investigation, it was discovered that the safe operating voltage was at 14.2kV thus making the device operate at 10kJ. The average neutron yield has been found to be in the order of 109 neutrons/pulse in 4πsr for the deuterium filling gas pressure range of 0.2 mbar to 10 mbar. Both the time integrated and time resolved techniques are employed to study the neutron emissions from this novel device. Using the first anode design (A20Z160)), maximum neutron yields has been found to be 2.38 × 109 neutrons/pulse for the pressure of 6 mbar. In using second anode design (A26Z160), it has been found that the peak neutron yield was 2.54 × 109 neutrons/pulse for the pressure of 5 mbar. In the third anode design (A55Z160), maximum neutron yield has been found to be 1.04 × 108 neutrons/pulse for the pressure of 0.25 mbar. In the fourth anode design (A20Z140), maximum neutron yield has been found to be 1.4 × 109 neutrons/pulse for the pressure of 6 mbar. In the fifth anode design (A26Z140), maximum neutron yield has been found to be 3.4 x 109 neutrons/pulse for the pressure of 6 mbar. Finally in the sixth anode design (A55Z70), maximum neutron yield has been found to be 1.1 × 109 neutrons/pulse for the pressure of 0.6 mbar.
Date Issued
2012
Call Number
QC718.5.D38 Has
Date Submitted
2012