Characteristics of Hydrogen Negative Ion Production depending on Electron Energy Distributions in Inductively Coupled Plasmas

학위논문 (박사)-- 서울대학교 대학원 : 에너지시스템공학부, 2015. 2. 김곤호.The goal of the RF driven hydrogen negative ion (H- ion) source driver developments is to promote the generation of H- ions and their precursors for a large extracted H- ion beam current with a high RF efficiency. Without full understanding the underlying physics of the hydrogen plasma chemistry and the inductively coupled plasma (ICP), it cannot comprehend phenomena in RF H- ion source drivers, then cannot also achieve this goal. To understand the underlying physics, the electron energy distribution function (EEDF) and H- ion generation in low-pressure inductively coupled hydrogen plasmas is investigated using both theoretical and empirical approaches. A global model was developed to investigate the densities of H- ions and other species in a low-pressure inductively coupled hydrogen plasma with a bi-Maxwellian EEDF. Compared to a Maxwellian plasma, bi-Maxwellian plasmas have higher populations of low-energy electrons and highly vibrationally excited hydrogen molecules that are generated efficiently by the high-energy electrons. This leads to higher reaction rates of the dissociative electron attachments responsible for H- ion production. The model indicated that the bi-Maxwellian EEDF at low pressures is favorable for the creation of H- ions. The dual frequency antenna ICP was developed to bi-Maxwellize the EEDF by controlling the driving frequency-dependent collisionless heating. The dual frequency antenna ICP consists of a 2 MHz-driven solenoidal antenna wound around a cylindrical chamber and a 13.56 MHz-driven planar antenna placed on the top of it. Compared to the conventional single frequency antenna ICPs, the dual frequency antenna ICP reveals two distinctive characteristics, i.e., an increase in the power transfer efficiency and the bi-Maxwellization of the EEDF due to the collisionless heating. These characteristics allow the dual frequency antenna ICP to accomplish the enhanced generation of H- ions and their precursors with a high RF efficiency. In addition, the source pulsing for the enhancement of the volume H- ion production was investigated by introducing the newly devised time derivative of EEDF – electron energy characteristic. The experimental result shows that H- ion density in the after-glow is about 17 times of that in the active-glow. It was found that this is due to the electron cooling in the after-glow and the long lifetime of highly vibrationally excited molecules.Contents Chapter 1 Introduction 1 1.1 Historical review of RF hydrogen negative ion source 1 1.2 Aims and objectives 9 Chapter 2 Fundamentals 13 2.1 Production and destruction of H– ion 13 2.2 H– ion source configuration 18 2.3 Electron energy distribution function 22 2.4 Inductively coupled plasma 25 2.5 Plasma Diagnostics 47 Chapter 3 Modeling of an inductive coupled hydrogen plasma 61 3.1 Global model of a hydrogen plasma 61 3.2 Electromagnetic model of an ICP 82 3.3 Analytic model of collisionless heating 87 Chapter 4 The relation between H– ion generation and EEDF 90 4.1 Experimental setup 90 4.2 Global model analysis of bi-Maxwellian H2 plasmas 93 Chapter 5 H– ion generation enhanced by ICP heating 121 5.1 Experimental setup 122 5.2 Bi-Maxwellization of the dual frequency antenna ICP 126 5.3 H– ion generation enhanced by bi-Maxwellization 140 Chapter 6 H– ion generation enhanced by pulsing 143 6.1 Experimental setup 145 6.2 H– ion generation in a pulsed ICP 147 6.3 The optimum pulse condition for obtaining the maximum average H– ion density in repetitive pulsed ICPs 165 Chapter 7 Conclusion 169 Appendix A Floating harmonics method for determination of EEDF 175 Appendix B Laser-assisted Hα spectroscopy for measurement of H– ion density 181 Bibliography 186 Abstract 198Docto

플라즈마 화학기상증착법을 이용한 다중벽 탄소나노튜브 합성에서 플라즈마 처리 효과에 관한 연구

Thesis(masters) --서울대학교 대학원 :에너지시스템공학부,2009.2.Maste

CAPACITIVE TYPE COUPLER STRUCTURE AND WIRELESS POWER TRANSFER SYSTEM INCLUDING THE CAPACITIVE TYPE COUPLER STRUCTURE

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커패시티브 결합방식의 커플러 구조 및 이를 포함하는 무선전력전송 시스템

【課題】新規なキャパシティブ結合方式のカプラー構造を提供すること。 【解決手段】キャパシティブ結合方式のカプラー構造は第1及び第2金属板を含む電力送信部及び、第3及び第4金属板を含む電力受信部を含み、第1金属板は第3金属板と第1キャパシターとを形成し、第2金属板は第4金属板と第2キャパシターとを形成し、第1ないし第4金属板が垂直に中央整列され容量性結合(capacitive coupling)を成すことを特徴とする。 【選択図】図

METHOD OF MODELING EQUIVALENT CIRCUIT OF MAGNETIC COUPLED COIL CIRCUIT IN WHICH TX COIL AND RX COIL ARE MISALIGNED IN CONDUCTIVE MEDIUM, AND WIRELESS POWER TRANSFER SYSTEM USING THE SAME

자기 결합 코일 회로의 등가 회로 모델링 방법은 자기 결합 코일 회로의 구성 특성을 나타내는 제1 파라미터, 전도성 매질의 특성을 나타내는 제2 파라미터, 및 상기 자기 결합 코일에 포함된 송신 코일과 수신 코일 사이의 오정렬 특성을 나타내는 제3 파라미터를 기초로 와전류 임피던스를 산출하는 단계, 상기 와전류 임피던스를 반영하여 상기 자기 결합 코일 회로의 Z-파라미터를 산출하는 단계, 및 상기 Z-파라미터를 기초로 상기 자기 결합 코일 회로의 2포트 등가 회로를 모델링하는 단계를 포함한다. 상기 와전류 임피던스는 제1 와전류 임피던스(Z11_eddy), 제2 와전류 임피던스(Z22_eddy), 및 제3 와전류 임피던스(Z21_eddy)를 포함한다. 상기 제3 와전류 임피던스는 상기 수신 코일의 탄젠셜(tangential) 성분 전기장을 선적분하여 산출된다