C-Band LINAC for a race track microtron

David Hume

Sujets

• Particulas

Informations

• Publié par: universidad_complutense_de_madrid
• Publié le: 01 janvier 2010
• Nombre de lectures: 35
• Langue: English
• Poids de l'ouvrage: 12 Mo

Extrait

UNIVERSIDAD COMPLUTENSE DE MADRID

FACULTAD DE CIENCIAS FÍSICAS
Departamento de Física Atómica, Molecular y Nuclear





C-BAND LINAC FOR A RACE TRACK
MICROTRON.


MEMORIA PARA OPTAR AL GRADO DE DOCTOR
PRESENTADA POR

David Carrillo Barrera


Bajo la dirección del doctor

Vasily Ivanovicht Shvedunov


Madrid, 2010



ISBN: 978-84-693-8239-4 © David Carrillo Barrera, 2010



CIEMAT
Unidad de Aceleradores

UNIVERSIDAD COMPLUTENSE DE MADRID
Departamento de Física Atómica, Molecular y Nuclear



TESIS DOCTORAL
LINAC EN BANDA C PARA UN MICROTRON
DE PISTA
C-BAND LINAC FOR A RACE TRACK
MICROTRON MICROTRON

Memoria realizada por
David Carrillo Barrera
para optar al grado de Doctor

Director de Tesis: Dr. Vasiliy Ivanovich Shvedunov

Madrid - 2010 CONTENTS CONTENTS

1 Introduction .............................................................................................................................. - 1 -
1.1 State of the art ........................ - 2 -
1.2 Objectives and thesis structure ............................................................................................... - 5 -
1.3 Introduction to Particle Accelerators ...................... - 7 -
1.3.1 The purpose of particle accelerators ........................................................................... - 7 -
1.3.2 History of accelerators ............................................................... - 10 -
1.3.3 Typical components in a particle accelerator ............................................................ - 20 -
1.3.3.1 Particle sources ........................................................................ - 20 -
1.3.3.2 RF cavities ................................................ - 20 -
1.3.3.3 Beam guiding and focusing devices ......... - 21 -
1.3.3.4 Injection and extraction devices .............................................. - 22 -
1.3.3.5 Diagnostics ............................................................................... - 23 -
1.4 Circular and race-track microtrons ....................................................... - 24 -
1.4.1 Circular Microtron ...................................................................................................... - 24 -
1.4.2 Race-Track Microtron (RTM)...................................................... - 26 -
1.4.2.1 Brief history of RTM ................................. - 26 -
1.4.2.2 Principles of operation ............................................................................................. - 26 -
1.4.2.3 Summary of RTM characteristics ............................................................................. - 29 -
1.4.3 RTM applications ...................................................................... - 30 -
1.4.3.1 Low energy nuclear physics ..................................................................................... - 31 -
1.4.3.2 Injectors ................................................... - 31 -
1.4.3.3 Radiotherapy ........................................................................... - 32 -
1.4.3.4 Elemental analysis ................................... - 32 -
1.4.3.5 Medical Isotopes Production ................................................................................... - 33 -
1.4.3.6 Cargo inspection ...... - 34 -
1.5 RTM parameters dependence on operating wavelength ...................................................... - 36 -
1.6 12 MeV RTM specification .................................................................................................... - 39 -
2 Accelerating Structures: Theoretical Background .... - 43 -
2.1 Basic microwave concepts .................................................................................................... - 43 -
2.1.1 Introduction ............................................................................... - 43 -
2.1.2 Waveguides and transmission lines ........... - 45 -
i
2.1.3 RF Cavities in accelerators ......................................................................................... - 47 -
2.2 Travelling and standing wave accelerating structures for electron linacs ............................ - 50 -
2.2.1 Travelling wave structures ......................................................................................... - 50 -
2.2.2 Standing wave structures .......................... - 52 -
2.3 Types of normal and superconducting standing wave accelerating structures .................... - 53 -
2.3.1 Normal Conducting Cavities ....................................................................................... - 53 -
2.3.2 Superconducting cavities ........................... - 53 -
2.4 Main parameters of the standing wave accelerating structure ............................................ - 55 -
2.4.1 Quality factor and external coupling with RF cavities ............... - 55 -
2.4.2 Electric field, energy gain, transit time factor, shunt impedance and synchronous
particle - 58 -
2.4.3 Coupling between cavities ......................................................................................... - 60 -
2.4.4 Pulsed and continuous mode: Duty factor ................................ - 60 -
2.5 Dependence of the standing wave accelerating structure parameters on wavelength........ - 61 -
2.6 Standing wave accelerating structure description in lumped circuit theory ......................... - 65 -
2.7 Modes of accelerating structure. Dispersion characteristic .................................................. - 68 -
2.8 Numerical methods and codes for accelerating structure optimization ............................... - 72 -
2.8.1 RTM Trace .................................................................................................................. - 72 -
2.8.2 Superfish .................... - 72 -
2.8.3 Ansys .......................................................................................................................... - 73 -
2.8.4 Ansoft HFSS ................................................ - 73 -
2.8.5 CST Studio ................. - 74 -
2.9 Main steps of standing wave accelerating structure optimization ....................................... - 75 -
3 C-band RTM linac optimization ................................................................ - 77 -
3.1 Peculiarities of RTM linac ...................................... - 77 -
3.2 RTM linac parameters specification ...................................................................................... - 79 -
3.3 Electrodynamics characteristics optimization ....................................................................... - 81 -
3.3.1 2D linac optimization with RF and beam dynamics codes ......................................... - 82 -
2.5.2.1 Regular =1 cell optimization ................................................................................. - 82 -
3.3.1.1 End =1 cell calculations .......................... - 86 -
3.3.1.2 First <1 cell calculation and linac optimization ...................... - 87 -
3.3.1.3 Summary of 2D linac optimization ........................................................................... - 91 -
3.3.2 3D linac cells calculation, coupling factor and field distribution optimization .......... - 92 -
3.3.2.1 Initial considerations ................................................................................................ - 92 -
ii
3.3.2.2 Order of 3D calculations: Methodology ................................................................... - 94 -
3.3.2.3 Step (a). Calculation of regular cell (2a=2b=3a=3b=4a) without coupling slots. ..... - 95 -
3.3.2.4 Step (b). Calculation of short end cell (1a+1b) without coupling slots. ................... - 97 -
3.3.2.5 Step (c). Tuning 2b+3a assembly with coupling slots .............................................. - 98 -
3.3.2.6 Steps (d), (e). Tuning 2a+1b+1a assembly with coupling slots. ............................ - 102 -
3.3.2.7 Step (f). Tuning 4b+4a+3b assembly with coupling slots ....... - 105 -
3.3.2.8 Step (g). Calculation of the full assembly: 1a+1b+2a+2b+3a+3b +4a+4b .............. - 107 -
3.3.2.9 Step (h) Optimization of accelerating structure coupling with waveguide ........... - 111 -
3.3.2.10 Summary of 3D linac optimization ......................................................................... - 118 -
3.3.3 Calculations of the tolerances for basic cell dimensions ......... - 119 -
3.3.4 Analysis of multipole fields caused by the coupling slots and waveguide ............... - 125 -
3.3.4.1 Effect of couplin