Inertial Electrostatic Confinement Fusion Reactor done.docx

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Queen's University
Engineering Physics Courses
ENPH 455
Jun Gao

Simulation and Optimization of an Inertial Electrostatic Confinement Fusion Reactor by Jimmy Zhan A thesis submitted to the Department of Physics Engineering Physics and Astronomy in conformity with the requirements of ENPH 455Supervisor Dr Robert KnobelFaculty of Applied Science and Engineering Queens University Kingston Ontario Canada April 2 2013 1AbstractThe Inertial Electrostatic Confinement Fusion Reactor IEC Fusion is a potential method for controlled fusion power The IEC fusion reactor confines plasma via a strong electrostatic potential between two concentric grids as ions stream towards the center The electrostatic potential between the outer grid and the inner grid is on the order of magnitude of tens of kilo volts and the outer grid is usually grounded Gas species such as Deuterium and Tritium are injected into a vacuum chamber housing the grids usually at pressures on the order of a millitorr Once ionized by the electric field the ions accelerate radially toward the central grid colliding with other ions of sufficient relative velocity to undergo fusion Those ions that shoot through the center without fusing will decelerate and fallback towards the center making another pass This method of confinement therefore has two advantages Plasma recirculates around the central grid making multiple passes and hence increasing the likelihood of fusion Optimal fusion cross section is on the order of hundred million Kelvins while difficult to achieve conventionally it translates to only tens of kilo electron volts which is fairly easy to achieve via electrostatics There are also difficulties associated with IEC fusion Several loss mechanisms limit its ultimate power output the most significant being Coulomb interactions causing bremsstrahlung radiation and thermalization of ion velocities and iongrid collisions This thesis investigates the fusion performance of a cylindrical IEC device this will be done via computational modelling and iterative numerical simulations of performance parameters A set of optimum design parameters will be derived from the simulations and a preliminary design for an IEC device will be given The results were not surprising there is an optimum operating voltage of approximately 190 kV The optimum pressure and chamber size is approximately 1 meter at 1 millitorr The grid transparency has a dramatic effect on the performance as well but this is material limited to 98 A novel method of reducing grid collisions is being researched by the US Navy currently in which electrons are trapped to form a virtual cathode using magnetic fields This is termed the Polywell2List of FiguresFigure 1 The original Farnsworth fusor9 Figure 2 HirschMeeks fusor9 Figure 3 The correct model for fusion cross section 1012 Figure 4 Coulomb interaction and Bremsstrahlung radiation of an electron and ion 1014 Figure 5 Charge exchange process of various isotopes of Hydrogen 15 15 Figure 6 Comparison of fusion performance of various anodecathode geometries 2916 Figure 7 The simulation reached near steady state in approximately 10 s with the number of ions and electrons equal 2917 Figure 8 Ionion reactions occur only inside the inner grid ionneutral collisions rate increases approaching the center and neutralneutral collisions occur uniformly throughout device 2917 Figure 9 A total neutron flux of roughly 88105 ns was achieved at a grid voltage of 100 kV and current of 40 mA 2918 Figure 10 The basic schematic of an IEC fusion reactor 1621 Figure 11 The simulation cell containing one macroparticle 2122 Figure 12 The Leapfrog method showing the time offset between position and velocity 2124 Figure 13 The dependence of fusion rate as a function of grid voltage The fuel pressure is kept at 0001 millitorr and the chamber radius is 1 m27 Figure 14 The dependence of the fusion rate plotted against the cathode grid transparency Note that this is a log plot The voltage is at 60 kV the fuel pressure is kept at 0001 millitorr and the chamber radius is 1 m28 Figure 15 The dependence of fusion rate on the input fuel gas pressure The voltage is kept at 60 kV and the chamber radius at 1 m29 Figure 16 The dependence of fusion rate on the chamber size The voltage is at 60 kV and the pressure is at 0001 millitorr30 Figure 17 The Paschen Curve for various gases illustrating the Paschen Minimum The breakdown voltage of air on either side of the minimum value has inverse relationship with the product of pressure and distance 3231 Figure 18 Optimum Design32 Figure 19 Optimum Design32 Figure 20 Fusion Rate of Optimum Design33 Figure 21 Definition of the hardsphere cross section model 1038 Figure 22 The Coulomb force repels the nuclear force attracts but only acts at a short range 1039 Figure 23 The classical model of fusion cross section 1040 Figure 24 The correct model of fusion cross section including the effects of tunneling resonance and highspeed decay 1041 Figure 25 Experimentally measured cross sections v for various fusion reactions of interest Notice that DT has a peak of 5 barns at 120 keV and is clearly favorable in comparison to DD 1041 Figure 26 v for various fusion reactions of interest as functions of temperature Note that the peak cross section for DT is at 70 keV 1042 3
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