重離子核聚變是一種能源技術，它有可能為人類未來提供無限的潔淨能源。通過高能粒子撞擊含高濃度氘和氚的目標，從而產生強大的壓縮衝擊波，最終引發氘和氚核子聚變並釋放出巨大核能。在過去的幾十年裡，從離子注入到核反應控制技術，以至於整個重離子核聚變的基本概念都得到迅速的發展。其中一個重要的核聚變條件就是要求非常低的離子束的縱向發射度。 / 在論文的第一部分，我們研發了一種TSC 技術，它可以減少因粒子加速器的電壓變化而引起的縱向發射度增長。通過數值模擬，結果表明離子束的縱向發射度得到了約89% 的降低。如果把TSC 技術應用於重離子核聚變，離子束的縱向發射度就可以有效地被降低，從而促進更高效的核聚變反應。在論文的第二部分，我們以離子束的電流信號分析為基礎，研發了一種非干擾性的離子束能量測量方法。對於傳統干擾性的離子束能量測量，這種強調非干擾性的測量方法對未來重離子核聚變實驗以及高能粒子加速器研發都有實質的應用價值。在論文的第三部分，我們從NDCX 實驗數據分析中，證實離子束的電流信號能夠有效地揭示離子束微弱的能量變化。這個實驗結果相應肯定了論文第二部分的電流信號分析處理方法。在論文的第四部分，我們模擬在真實的NDCX 環境下測試TSC 技術。模擬結果表明TSC 技術可有效地把離子束的縱向發射度減少近89% ，從而證明了TSC 技術在實際應用中的能力。在論文的最後部分，我們在強電流離子束的一維波動行為中引入橫縱向稱合分析，解釋了一維波動行為與數值模擬結果之間的細小偏差。 / Heavy Ion Fusion (HIF) is a technology that has the potential to provide an unlimited source of clean energy for human future. HIF works by shooting at a capsule containing Deuterium and Tritium with energetic heavy ion beams such that the huge amount of kinetic energy carried by the ions is converted into strong compression shock waves. DT fuel is then compressed to form a high temperature and high density hotspot at the center of the capsule, thus igniting nuclear fusion between Deuterium and Tritium. Over the past few decades, the fundamental concepts of HIF had been tested in scaled ex¬periments from the source injection to the reaction chamber. To achieve the highest performance of ignition, ion beams with low longitudinal emittance is demanded. / In the first part of the thesis, we developed a novel Two-Step Correction (TSC) technique to reduce the growth of longitudinal emittance in an induc¬tion linac driver caused by variations in acceleration gap voltages. Through numerical studies, we achieved a reduction of longitudinal emittance by about 89% for high perveance ion beams. As a spinoff from the formalism developed in this study, we developed in the second part of the thesis a new non-invasive approach for the measurement of ion beam energy. The proposed diagnostics may have practical utility for future HIF experiments, particularly as higher energy accelerators are developed. It works by a generalized time-of-flight method, using two adjacent beam current signals to reconstruct the beam velocity profile. In the third part of the thesis, we verified that beam current signals are capable to reveal small beam energy variations by an NDCX-I experiment performed at Lawrence Berkeley National Laboratory. The result of this experiment confirms the formalism of the new non-invasive approach for the ion beam energy determination based on beam current signal analysis. In order to verify the effectiveness of TSC in real drivers, we proposed a new NDCX-I experiment in the fourth part of the thesis to test the limitations and performance of the correction technique in real environment. Through simulations with real driver features considered, a reduction of 89% of longitudinal emittance was observed, which confirms the ability of TSC in real applications. In the last part of the thesis, we revealed the limitation of the 1-D cold fluid model deployed in our analysis of space-charge waves for high perveance ion beams. We showed that inaccuracies are caused by transverse-longitudinal coupling which could be included in the wave equation for space-charge dominated beams. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Woo, Ka Ming = 抑制由粒子加速器的電壓變化所引起的縱向發射度 / 胡家明. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references (leaves 153-156). / Abstracts also in Chinese. / Woo, Ka Ming = Yi zhi you li zi jia su qi de dian ya bian hua suo yin qi de zong xiang fa she du / Hu Jiaming. / Abstract --- p.ii / 概論 --- p.iv / Acknowledgement --- p.v / Chapter 1 --- Introduction --- p.1 / Chapter 2 --- Background --- p.4 / Chapter 2.1 --- Highlight --- p.4 / Chapter 2.2 --- Introduction to fusion energy --- p.4 / Chapter 2.3 --- Fusion technology --- p.5 / Chapter 2.3.1 --- Magnetic confinement fusions --- p.5 / Chapter 2.3.2 --- Inertial confinement fusions --- p.7 / Chapter 2.4 --- Inertia confinement fusion --- p.9 / Chapter 2.4.1 --- Principle of ICF --- p.9 / Chapter 2.4.2 --- Implosion dynamics --- p.11 / Chapter 2.4.3 --- Rayleigh-Taylor instability --- p.13 / Chapter 2.4.4 --- Fast ignition --- p.14 / Chapter 2.5 --- Heavy Ion Fusion --- p.16 / Chapter 2.5.1 --- Comparison between laser and heavy ion driven fusions --- p.16 / Chapter 2.5.2 --- Linear Induction Accelerator --- p.18 / Chapter 2.6 --- Operation of a HIF driver --- p.20 / Chapter 2.6.1 --- Source injection --- p.20 / Chapter 2.6.2 --- Transport of ion beams --- p.21 / Chapter 2.6.3 --- Acceleration of ion beams --- p.22 / Chapter 2.6.4 --- Neutralized drift longitudinal compression --- p.24 / Chapter 2.6.5 --- Target chamber --- p.25 / Chapter 2.7 --- Transverse beam dynamics --- p.26 / Chapter 2.7.1 --- Beam envelope equation --- p.26 / Chapter 2.7.2 --- Matched beams solutions --- p.29 / Chapter 2.8 --- Longitudinal beam dynamics --- p.30 / Chapter 2.8.1 --- Cold plasma model --- p.30 / Chapter 2.8.2 --- Self longitudinal electric field --- p.32 / Chapter 2.8.3 --- Longitudinal emittance --- p.34 / Chapter 2.9 --- Intense ion beam simulation --- p.35 / Chapter 2.9.1 --- Particle-In-Cell method --- p.35 / Chapter 2.9.2 --- WARP code --- p.36 / Chapter 2.10 --- Conclusion --- p.37 / Chapter 3 --- Techniques for correcting velocity and density fluctuations of ion beams --- p.39 / Chapter 3.1 --- Highlight --- p.39 / Chapter 3.2 --- The quest for short-pulse length ion beams --- p.40 / Chapter 3.2.1 --- Applications of short-pulse ion beams --- p.40 / Chapter 3.2.2 --- Consequence of the growth of longitudinal emittance --- p.41 / Chapter 3.3 --- Effect of gap voltage variation on εzn --- p.42 / Chapter 3.3.1 --- Description of simulation scenario --- p.42 / Chapter 3.3.2 --- The coasting of an unperturbed ion beam and a velocitytilt beam --- p.43 / Chapter 3.3.3 --- Effect of many constant voltage gaps --- p.44 / Chapter 3.3.4 --- Effect of non-uniform voltage gap --- p.46 / Chapter 3.4 --- One-step correction --- p.48 / Chapter 3.4.1 --- Criteria for the one-step correction --- p.52 / Chapter 3.4.2 --- Space-charge dominated beams --- p.55 / Chapter 3.5 --- Two-step correction --- p.56 / Chapter 3.5.1 --- Principle of two-step correction --- p.56 / Chapter 3.5.2 --- Result of two-step correction --- p.59 / Chapter 3.6 --- Conclusion --- p.62 / Chapter 4 --- A new non-invasive approach for the measurement of ion beam energy --- p.63 / Chapter 4.1 --- Highlight --- p.63 / Chapter 4.2 --- Introduction --- p.64 / Chapter 4.3 --- Derivation of the ion beam energy based on two current signals --- p.65 / Chapter 4.3.1 --- Obtaining the time evolution of the beam current --- p.65 / Chapter 4.3.2 --- Deriving the beam energy profile --- p.67 / Chapter 4.3.3 --- Obtaining the average velocity --- p.70 / Chapter 4.4 --- Checking the beam energy profile with 3-D PIC simulations --- p.72 / Chapter 4.4.1 --- Determination of the average velocity --- p.73 / Chapter 4.4.2 --- Computation of the beam energy profile --- p.74 / Chapter 4.5 --- Signal magnification --- p.74 / Chapter 4.6 --- Error propagations --- p.77 / Chapter 4.7 --- Conclusion --- p.81 / Chapter 5 --- Experimental verification of the beam current signal amplification --- p.83 / Chapter 5.1 --- Highlight --- p.83 / Chapter 5.2 --- Introduction to NDCX-I --- p.84 / Chapter 5.3 --- Design of the NDCX-I experiment --- p.88 / Chapter 5.4 --- Voltage profiles applied at the source plate --- p.90 / Chapter 5.4.1 --- Marx voltage profile --- p.90 / Chapter 5.4.2 --- Voltage modulation --- p.91 / Chapter 5.5 --- Signal amplification of beam currents measured at the Faraday cup --- p.92 / Chapter 5.6 --- Modeling of the space-charge wave propagation --- p.94 / Chapter 5.6.1 --- Solving for the line-charge density profile at the source plate --- p.94 / Chapter 5.6.2 --- Procedure of space-charge wave modeling --- p.99 / Chapter 5.7 --- Conclusion --- p.101 / Chapter 6 --- Implementation of Two-Step Correction in NDCX-I --- p.103 / Chapter 6.1 --- Highlight --- p.103 / Chapter 6.2 --- Application of the current signal analysis to the Two-Step Correction --- p.104 / Chapter 6.3 --- Proposal of the new NDCX-I experiment --- p.107 / Chapter 6.3.1 --- Design of the beamline --- p.107 / Chapter 6.3.2 --- Description of the simulation scenario --- p.110 / Chapter 6.3.3 --- Result of the Two-Step Correction simulation --- p.114 / Chapter 6.4 --- Conclusion --- p.126 / Chapter 7 --- Transverse-Longitudinal coupling in the wave equation --- p.128 / Chapter 7.1 --- Highlight --- p.128 / Chapter 7.2 --- Phenomenological study of residue --- p.129 / Chapter 7.2.1 --- Description of the simulation scenario --- p.129 / Chapter 7.2.2 --- Modeling of the velocity wave --- p.131 / Chapter 7.2.3 --- Phenomenon of residue --- p.133 / Chapter 7.3 --- Review of the space-charge wave equation --- p.141 / Chapter 7.3.1 --- Fluid description of ion beams --- p.141 / Chapter 7.3.2 --- Beam envelope perturbation --- p.145 / Chapter 7.4 --- Conclusion --- p.149 / Chapter 8 --- Conclusion --- p.150 / Bibliography --- p.153
| Identifer | oai:union.ndltd.org:cuhk.edu.hk/oai:cuhk-dr:cuhk_328593 |
| Date | January 2012 |
| Contributors | Woo, Ka Ming., Chinese University of Hong Kong Graduate School. Division of Physics. |
| Source Sets | The Chinese University of Hong Kong |
| Language | English, Chinese |
| Detected Language | English |
| Type | Text, bibliography |
| Format | electronic resource, electronic resource, remote, 1 online resource (xx, 156 leaves) : ill. (some col.) |
| Rights | Use of this resource is governed by the terms and conditions of the Creative Commons “Attribution-NonCommercial-NoDerivatives 4.0 International” License (http://creativecommons.org/licenses/by-nc-nd/4.0/) |
Page generated in 0.0033 seconds