Lau, Yuk Yeung = 重離子核聚變驅動設備的最終壓縮離子束線系統 / 劉鈺暘. / "November 2011." / Thesis (M.Phil.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references (p. 99-101). / Abstracts in English and Chinese. / Lau, Yuk Yeung = Zhong li zi he ju bian qu dong she bei de zui zhong ya suo li zi shu xian xi tong / Liu Yuyang. / Abstract --- p.i / 概要 --- p.iii / Acknowledgements --- p.iv / Chapter 1 --- Introduction --- p.1 / Chapter 2 --- Background --- p.5 / Chapter 2.1 --- Nuclear fusion --- p.5 / Chapter 2.1.1 --- Nuclear fusion as an energy source --- p.5 / Chapter 2.1.2 --- Lawson criterion --- p.7 / Chapter 2.1.3 --- Confinement method --- p.8 / Chapter 2.2 --- Inertial confinement fusion --- p.11 / Chapter 2.2.1 --- Driving beams --- p.11 / Chapter 2.2.2 --- Reactor chamber --- p.14 / Chapter 2.2.3 --- Ignition target --- p.14 / Chapter 2.3 --- Heavy ion inertial confinement fusion --- p.16 / Chapter 2.3.1 --- Beam source and accelerator system --- p.18 / Chapter 2.3.2 --- Drift compression section --- p.20 / Chapter 2.4 --- Beam dynamics --- p.23 / Chapter 2.4.1 --- Transverse dynamics --- p.24 / Chapter 2.4.2 --- Longitudinal dynamics --- p.26 / Chapter 2.4.3 --- Emittance --- p.27 / Chapter 2.5 --- Simulation codes --- p.28 / Chapter 2.5.1 --- Particle in cell simulation --- p.28 / Chapter 2.5.2 --- WARP code --- p.29 / Chapter 3 --- Drift compression beamline system for heavy ion fusion drivers --- p.31 / Chapter 3.1 --- Beam requirements for target implosion in HIF driver --- p.31 / Chapter 3.2 --- Drift compression beamline configuration --- p.33 / Chapter 3.3 --- Simulation example --- p.39 / Chapter 3.4 --- Minimization of centroid offset with bend strategies --- p.42 / Chapter 3.5 --- Neutralized drift section and final focusing --- p.50 / Chapter 3.6 --- "Final pulse length, spot size and emittance" --- p.52 / Chapter 4 --- Longitudinal emittance growth due to non-linear space charge effects --- p.61 / Chapter 4.1 --- Longitudinal emittance growth in the linear regime - Simulation results --- p.62 / Chapter 4.2 --- Longitudinal emittance growth in the linear regime - analytical results --- p.67 / Chapter 4.2.1 --- Beam with uniform radius --- p.68 / Chapter 4.2.2 --- Beam with uniform density --- p.73 / Chapter 4.2.3 --- Comparison with simulations --- p.76 / Chapter 4.2.4 --- Extension to more general beams --- p.78 / Chapter 4.3 --- Longitudinal emittance evolution in the nonlinear regime --- p.79 / Chapter 4.4 --- Target pulse length minimization --- p.86 / Chapter 4.4.1 --- Optimization of drift compression beamline and beam parameters --- p.86 / Chapter 4.4.2 --- Phase space correction with initial voltage waveform tailoring --- p.90 / Chapter 4.5 --- Coupling of Longitudinal and Transverse Emittances --- p.91 / Chapter 5 --- Summary --- p.95 / Bibliography --- p.99

A Moak type radio frequency ion source, capable of producing a pulsed beam of deuterons has been built for use with a Cockcroft-Walton accelerator. Pulsed deuterons striking a deuteron target produce neutrons in bursts thus allowing dynamic measurements of moderator and reactor core properties. Beam pulsing is accomplished by means of an einzel lens and an alternating potential applied to a pair of deflection plates. Proteins have been used exclusively in adjusting the source for optimum results since the radiation background due to the protons is much less than that due to deuterons. In actual experiments, however, when using deuterons, no modifications need to be made in the source. Beam currents have been measured at the source and at a target located at the end of the accelerator tube. Maximum currents measured are 150 microamperes and 60 microamperes respectively. Details of construction, maximum operating conditions, and oscillogram sof purse shapes are included in this report. / M.S.

Beams of polarized protons play an important part in the study of the spin dependence of the nuclear force by measuring the analyzing power in nuclear reactions. The source at iThemba LABS produces a beam of polarized protons that is pre-accelerated by an injector cyclotron (SPC2) to a energy of 8 MeV before acceleration by the main separated-sector cyclotron to 200 MeV for physics research. The polarized ion source is one of the two external ion sources of SPC2. Inside the ion source hydrogen molecules are dissociated into atoms in the dissociator and cooled to a temperature of approximately 30 K in the nozzle. The atoms are polarized by a pair of sextupole magnets and the nucleus is polarized by RF transitions between hyperfine levels in hydrogen atoms. The atoms are then ionized by electrons in the ionizer. The source has various sensitive devices, which influence beam intensity and polarization. Nitrogen gas is used to prevent recombination of atoms after dissociation. The amount of nitrogen and the temperature at which it is used plays a very important role in optimizing the beam current. The number of electrons released in the ionizer is influenced by the size and shape of the filament. Optimization of the source will ensure that beams of better quality (a better current and stability) are produced.

Beams of polarized protons play an important part in the study of the spin dependence of the nuclear force by measuring the analyzing power in nuclear reactions. The source at iThemba LABS produces a beam of polarized protons that is pre-accelerated by an injector cyclotron (SPC2) to a energy of 8 MeV before acceleration by the main separated-sector cyclotron to 200 MeV for physics research. The polarized ion source is one of the two external ion sources of SPC2. Inside the ion source hydrogen molecules are dissociated into atoms in the dissociator and cooled to a temperature of approximately 30 K in the nozzle. The atoms are polarized by a pair of sextupole magnets and the nucleus is polarized by RF transitions between hyperfine levels in hydrogen atoms. The atoms are then ionized by electrons in the ionizer. The source has various sensitive devices, which influence beam intensity and polarization. Nitrogen gas is used to prevent recombination of atoms after dissociation. The amount of nitrogen and the temperature at which it is used plays a very important role in optimizing the beam current. The number of electrons released in the ionizer is influenced by the size and shape of the filament. Optimization of the source will ensure that beams of better quality (a better current and stability) are produced.

Magister Scientiae - MSc / Beams of polarized protons play an important part in the study of the spin dependence of the nuclear force by measuring the analyzing power in nuclear reactions. The source at iThemba LABS produces a beam of polarized protons that is pre-accelerated by an injector cyclotron (SPC2) to a energy of 8 MeV before acceleration by the main separated-sector cyclotron to 200 MeV for physics research. The polarized ion source is one of the two external ion sources of SPC2. Inside the ion source hydrogen molecules are dissociated into atoms in the dissociator and cooled to a temperature of approximately 30 K in the nozzle. The atoms are polarized by a pair of sextupole magnets and the nucleus is polarized by RF transitions between hyperfine levels in hydrogen atoms. The atoms are then ionized by electrons in the ionizer. The source has various sensitive devices, which influence beam intensity and polarization. Nitrogen gas is used to prevent recombination of atoms after dissociation. The amount of nitrogen and the temperature at which it is used plays a very important role in optimizing the beam current. The number of electrons released in the ionizer is influenced by the size and shape of the filament. Optimization of the source will ensure that beams of better quality (a better current and stability) are produced. / South Africa

<p>During operation of heavy ion accelerators a significant pressure rise has been observed when the intensity of the high energy beam was increased. The cause for this pressure rise is ion induced desorption, which is the result when beam ions collide with residual gas molecules in the accelerator, whereby they undergo charge exchange. Since the change in charge state will affect the bending radius of the particles after they have passed a bending magnet, they will not follow the required trajectory but instead collide with the vacuum chamber wall and gas are released. For the Future GSI project FAIR (Facility for Antiproton and Ion Research) there is a need to upgrade the SIS18 synchrotron in order to meet the requirements of the increased intensity. The aim of this work was to measure the desorption yields, η, (released molecules per incident ion) from materials commonly used in accelerators: 316LN stainless steel, Cu, Etched Cu, gold coated Cu, Ta and TiZrV coated stainless steel with argon and uranium beams at the energies 5-100 MeV/u. The measurements were performed at GSI and at The Svedberg Laboratory where a new dedicated teststand was built. It was found that the desorption yield scales with the electronic energy loss to the second power, decreasing for increasing impact energy above the Bragg Maximum. A feasibility study on the possibility to use laser refractometry to improve the accuracy of a specific throughput system was performed. The result was an improvement by up to 3 orders of magnitude, depending on pressure range.</p>

During operation of heavy ion accelerators a significant pressure rise has been observed when the intensity of the high energy beam was increased. The cause for this pressure rise is ion induced desorption, which is the result when beam ions collide with residual gas molecules in the accelerator, whereby they undergo charge exchange. Since the change in charge state will affect the bending radius of the particles after they have passed a bending magnet, they will not follow the required trajectory but instead collide with the vacuum chamber wall and gas are released. For the Future GSI project FAIR (Facility for Antiproton and Ion Research) there is a need to upgrade the SIS18 synchrotron in order to meet the requirements of the increased intensity. The aim of this work was to measure the desorption yields, η, (released molecules per incident ion) from materials commonly used in accelerators: 316LN stainless steel, Cu, Etched Cu, gold coated Cu, Ta and TiZrV coated stainless steel with argon and uranium beams at the energies 5-100 MeV/u. The measurements were performed at GSI and at The Svedberg Laboratory where a new dedicated teststand was built. It was found that the desorption yield scales with the electronic energy loss to the second power, decreasing for increasing impact energy above the Bragg Maximum. A feasibility study on the possibility to use laser refractometry to improve the accuracy of a specific throughput system was performed. The result was an improvement by up to 3 orders of magnitude, depending on pressure range.