Superconducting Radiofrequency Technology for Accelerators: State of the Art and Emerging Trends

Cover
Title Page
Copyright
Contents
Preface
Part I Update of SRF Fundamentals
Chapter 1 Introduction
Chapter 2 SRF Fundamentals Review
2.1 SRF Basics
2.2 Fabrication and Processing on Nb‐Based SRF Structures
2.2.1 Cavity Fabrication
2.2.2 Preparation
2.2.3 A Decade of Progress
2.3 SRF Physics
2.3.1 Zero DC Resistance
2.3.2 Meissner Effect
2.3.3 Surface Resistance and Surface Impedance in RF Fields
2.3.4 Nonlocal Response of Supercurrent
2.3.5 BCS
2.3.6 Residual Resistance
2.3.7 Smearing of Density of States
2.3.8 Ginzburg–Landau (GL) Theory
2.3.9 Critical Fields
2.3.10 Comparison Between Ginzburg–Landau and BCS
2.3.11 Derivation of Rs and Xs
Part II High Q Frontier: Performance Advances and Understanding
Chapter 3 Nitrogen‐Doping
3.1 Introduction
3.2 N‐Doping Discovery
3.3 Surface Nitride
3.4 Interstitial N
3.5 Electron Mean Free Path Dependence
3.5.1 LE‐µSR Measurements of Mean Free path
3.6 Anti‐Q‐Slope Origins from BCS Resistance
3.7 N‐Doping and Residual Resistance
3.7.1 Trapped DC Flux Losses
3.7.2 Residual Resistance from Hydride Losses
3.7.3 Tunneling Measurements
3.8 RF Field Dependence of the Energy Gap
3.9 Frequency dependence of Anti‐Q‐Slope
3.10 Theories for Anti‐Q‐Slope
3.10.1 Xiao Theory
3.10.2 Gurevich Theory
3.10.3 Nonequilibrium Superconductivity
3.10.4 Two‐Fluid Model‐Based on Weak Defects
3.11 Quench Field of N‐Doped Cavities
3.12 Evolution and Comparison of N‐doping Recipes
3.13 High Q and Gradient R&D Program for LCLS‐HE
3.14 N‐Doping at Other Labs
3.15 Summary of N‐doping
Chapter 4 High Q via 300 °C Bake (Mid‐T‐Bake)
4.1 A Surprise Discovery
4.2 Similarities to N‐Doping
4.3 Mid‐T Baking at Other Labs
4.4 The Low‐Field Q‐Slope (LFQS) and 340 °C Baking Cures
4.5 Losses at Very Low Fields
4.6 Losses from Two‐Level Systems (TLS)
4.7 Eliminating TLS Losses
Chapter 5 High Q\stquote s from DC Magnetic Flux Expulsion
5.1 Trapped Flux Losses, Sensitivity
5.2 Trapped Flux Sensitivity Models
5.3 Vortex Physics
5.4 Calculation of Sensitivity to Trapped Flux
5.5 Dependence of Sensitivity on RF Field Amplitude
5.6 DC Magnetic Flux Expulsion
5.6.1 Fast versus Slow‐Cooling Discovery
5.6.2 Thermoelectric Currents
5.7 Cooling Rates for Flux Expulsion
5.8 Flux Expulsion Patterns
5.9 Geometric Effects – Flux Hole
5.10 Flux Trapping With Quench
5.11 Material Quality Variations
5.12 Modeling Flux Trapping From Pinning Variations
Part III High Gradient Frontier: Performance Advances and Understanding
Chapter 6 High‐Field Q Slope (HFQS) – Understanding and Cures
6.1 HFQS Summary
6.2 HFQS in Low‐β Cavities
6.3 Deconvolution of RBCS and Rres
6.4 Depth of Baking Effect
6.4.1 From Anodization
6.4.2 From HF Rinsing
6.4.3 Depth of Magnetic Field Penetration by LE‐μSR
6.5 Role of the Oxide Layer and Role of N‐Infusion
6.6 SIMS Studies of O, H, and OH Profiles
6.7 Hydrogen Presence in HFQS
6.8 TEM Studies on Hydrides
6.9 Niobium–hydrogen Phase Diagram
6.10 H Enrichment at Surface
6.11 Q‐disease Review
6.12 Visualizing Niobium Hydrides
6.12.1 Cold‐stage Confocal Microscopy
6.12.2 Cold‐stage Atomic Force Microscopy (AFM)
6.13 Model for HFQS – Proximity Effect Breakdown of Nano‐hydrides
6.13.1 Baking Benefit and Proximity Effect Model
6.14 Positron Annihilation Studies of HFQS and Baking Effect
6.15 Point Contact Tunneling Studies of HFQS and Baking Effect
Chapter 7 Quest for Higher Gradients: Two‐Step Baking and N‐Infusion
7.1 Two‐Step Baking
7.2 Subtle Effects of Two‐Step Baking – Bifurcation
7.2.1 Bifurcation Reduction
7.3 N‐Infusion at 120 °C
7.4 N‐Infusion at Medium Temperatures
7.5 Unifying Quench Fields
7.6 Quench Detection by Second Sound in Superfluid Helium
Chapter 8 Improvements in Cavity Preparation
8.1 Comparisons of Cold and Warm Electropolishing Methods
8.2 Chemical Soaking
8.3 Optical Inspection System and Defects Found
8.4 Robotics in Cavity Preparation
8.5 Plasma Processing to Reduce Field Emission
Chapter 9 Pursuit of Higher Performance with Alternate Materials
9.1 Nb Films on Cu Substrates
9.1.1 Direct Current Magnetron Sputtering
9.1.2 DC‐bias Diode Sputtering at High Temperature (400–600 °C)
9.1.3 Seamless Cavity Coating
9.1.4 Nb–Cu Films by ECR
9.1.5 Nb–Cu Films via High‐Power Impulse Magnetron Sputtering (HIPIMS)
9.2 Alternatives to Nb
9.2.1 Nb3Sn
9.2.2 MgB2
9.2.3 NbN and NbTiN
9.3 Multilayers
9.3.1 SIS\stquote Structures
9.3.2 Theoretical Estimates
9.3.3 Results
9.3.4 SS\stquote Structures
9.4 Summary
Part IV Applications
Chapter 10 New Cavity Developments
10.1 Crab Cavities for LHC High Luminosity
10.2 Short‐Pulse X‐Rays (SPX) System for the APS Upgrade
10.3 QWR Cavity for Acceleration
10.4 Traveling Wave Structure Development
Chapter 11 Ongoing Applications
11.1 Overview
11.2 Low‐Beta Accelerators for Nuclear Science and Nuclear Astrophysics
11.2.1 ATLAS at Argonne
11.2.2 ISAC and ISAC‐II at TRIUMF
11.2.3 SPIRAL II at GANIL
11.2.4 HIE ISOLDE
11.2.5 RILAC at RIKEN
11.2.6 SPES Upgrade of ALPI at INFN
11.2.7 FRIB at MSU
11.2.8 RAON
11.2.9 Spoke Resonator Structure Developments to Avoid Multipacting
11.2.10 JAEA Upgrade
11.2.11 HELIAC
11.2.12 SARAF
11.2.13 HIAF at IMP
11.2.14 IFMIF
11.3 High‐Intensity Proton Accelerators
11.3.1 SNS
11.3.2 ESS
11.3.3 Accelerator Driven Systems (CADS)
11.3.4 CiADS (China Initiative Accelerator Driven System)
11.3.5 Japan Atomic Energy Agency (JAEA) – ADS
11.3.6 High‐Intensity Proton Accelerator Development in India
11.3.7 PIP‐II and Beyond
11.4 Electrons for Light Sources – Linacs
11.4.1 European X‐ray Free Electron Laser (EXFEL)
11.4.2 Linac Coherent Light Source LCLS‐II and LCLS‐HE (LCLS‐High Energy)
11.4.3 Shanghai Coherent Light Facility (SCLF) SHINE
11.4.4 Institute of Advanced Science Facilities (IASF)
11.4.5 Polish Free‐Electron Laser POLFEL
11.5 Electrons for Storage Ring Light Sources
11.5.1 High‐Energy Photon Source (HEPS)
11.5.2 Taiwan Photon Source (TPS)
11.5.3 Higher Harmonic Cavities for Storage Rings Chaoen WANG, NSRRC, Taiwan
11.5.4 BNL
11.6 Electrons in Energy Recovery Linacs (ERL) for Light Sources & Electron–Ion Colliders
11.6.1 Prototyping ERL Technology at Cornell
11.6.2 KEK ERLs
11.6.3 Light‐House Project for Radiopharmaceuticals
11.6.4 Peking ERL
11.6.5 Berlin ERL
11.6.6 MESA ERL
11.6.7 SRF Photo‐injectors for ERLs
11.7 Electrons for Nuclear Physics, Nuclear Astrophysics, Radio‐Isotope Production
11.7.1 CEBAF at Jefferson Lab
11.7.2 ARIEL at TRIUMF
11.7.3 ERL for LHeC at CERN
11.8 Crab Cavities for LHC High Luminosity
11.9 Ongoing and Near‐Future Projects Summary
Chapter 12 Future Prospects for Large‐Scale SRF Applications
12.1 The International Linear Collider (ILC) for High‐Energy Physics
12.2 Future Circular Collider FCCee
12.3 China Electron–Positron Collider, CEPC
Chapter 13 Quantum Computing with SRF Cavities
13.1 Introduction to Quantum Computing
13.2 Qubits
13.3 Superposition and Coherence
13.4 Entanglement
13.5 2D SRF Qubits
13.6 Josephson Junctions
13.7 Dilution Refrigerator for Milli‐Kelvin Temperatures
13.8 Quantum Computing Examples
13.9 3D SRF Qubits
13.10 Cavity QED Quantum Processors and Memories
References
List of Symbols
List of Acronyms
Index
EULA