Joint Universities Accelerator School
Course 2 - The Technology & Applications of Particle Accelerators
Material for the lectures on “Introduction to RF” and “Introduction to magnets” is posted on the INDICO site well in advance of the beginning of the Course. Students are expected to study this material before the Course starts.

 

RF Engineering

Circuit theory: Propagation of electromagnetic waves on transmission lines  /  Smith chart  /  Scattering matrix  /  Impedance transformations by transmission lines

RF cavities - Theory and practice: Equivalent lumped circuit  /  Maxwell's equations  /  Cavity modes  /  Scaling law  /  Coupling  /  Tuning  /  Multipactor  /  Voltage breakdown  /  Measurements

Active elements (transistors, tubes, klystrons)

Prerequisites: knowledge of basic mathematics, equipment (pocket calculator) to carry out numerical calculations involving complex quantities

 

Vacuum systems

Basics of vacuum science and technology; Physical units  /  kinetic theory of gases  /  Gas flow and pressure distribution calculations in complex vacuum systems

Fundamentals of gas-surface interactions leading to outgassing  /  Physisorption  /  Chemisorption  /  Diffusion of gases in solids and surface phenomena

Dynamic outgassing under particle bombardment

Vacuum systems, usual materials and components  /  Surface and bulk cleanliness definition  /  Diagnostics and preparation treatments

Pumps, gauges  /  Gas analysers  /  Leak detectors

Specificities of accelerator vacuum systems  /  Lumped versus distributed pumping devices  /  General review of beam-vacuum interactions and related problems

 

Beam instrumentation

The course gives an overview of the most frequently used beam diagnostics instruments at electron and proton accelerators, putting about equal weight to LINACs and synchrotrons. In addition, applications for their usage during operation and accelerator physics investigation are discussed.

The outline of the lecture is orientated on the beam quantities:

Beam current measurements using transformers  /  Faraday cups and particle detectors

Beam profile measurements using various methods such as scintillators screens, SEM-grids, wire scanners, residual gas monitors and synchrotron radiation

Transverse emittance measurements with slit-grid devices or reconstruction using quadrupole variation

The principle of RF pick-ups for beam position measurements as well as tune or other lattice function determinations

Longitudinal measurements of momentum spread and bunch structure using picks-ups, particle detectors or synchrotron radiation

Beam loss detection for beam alignment and machine protection.

Prerequisites: A good knowledge of general physics is required, as well as the basics in accelerator theory. The first year university mathematics is presumed, including matrix calculus, Fourier transformation and complex numbers. Only basic knowledge of detector physics, high frequency technologies and electronics is needed, more complex devices is discussed.

 

Superconducting RF Cavities

Surface resistance and field limitations: Multipacting, quenches, fField emission

Superconducting cavity design: Optimal shape, tuning, field flatness, coupling ports  / Lorentz force detuning and instabilities  /  Fabrication techniques  /  Measurement techniques

Superconducting cavity and its RF system: Coupling to a matched line, external Q  /  Resonant coupling  /  Main and HOM couplers  /  RF power and system stability

Typical applications: Electron machines, high field, high current  /  Low and reduced beta cavities for linacs

 

Accelerator controls

The course gives an overview of Accelerator Control Systems, their purpose, and their architecture. Commonly used hardware is introduced by examples. Finally the borders of a Control System are briefly discussed.

 

Normal Conducting magnets

This course is meant as an introduction in magnet technology focusing on normal-conducting, iron-dominated electro-magnets.

The main goals are to create a fundamental understanding of electro-magnets used for particle accelerators and beam transfer lines, to provide a guide book with instructions how to start with the design of a standard accelerator magnet and to present aspects related to magnet construction, manufacturing, testing and measurements.

The theoretical part will be interleaved by a number of practical examples and a case study where students will design a real-world magnet for a medical particle accelerator. 

Introduction: Historical background  /  Basic principles and concepts of accelerator magnets  /  The role of the magnetic circuit  /  Particularities of magnetic steel  /  Magnet types and their functions

Analytical magnet design: Understanding the requirements  /  The analytical design process  /  Magnet components and their purpose  /  Designing the magnetic circuit  /  Coil dimensioning and cooling layout

Magnet manufacturing: The magnet lifecycle  /  The manufacturing process  /  Material selection: magnetic steel, insulation materials, conductor materials  /  Modern production techniques  /  Auxiliary magnet components  /  Cost estimates and cost optimization

Quality assurance: Sample testing  /  Evaluating the performance of a magnet  /  Recurrent quality issues  /  Magnetic measurement techniques

Applied numerical design: the numerical design process  /  Building a 2D finite-element model  /  Interpretation of results  /  Improvement of the field quality and pole profile optimization  /  The importance of mechanical tolerances and the consequence of assembly errors  /  Limitations of numerical calculations

 

Superconducting magnets

Introduction to Superconductors : Critical field, temperature & current  /  superconductors for magnets  /  Manufacture of superconducting wires  /  High temperature superconductors HTS  /  Xhere to find out more

Magnetization, Cables & AC losses:  Superconductors in changing fields, critical state model  /  Filamentary superconductors and magnetization   /  Coupling between filaments & magnetization  /  Why cables, coupling in cables  /  Mini tutorial on magnetization  /  AC losses in changing fields

Magnets, ‘Training’ & Fine Filaments: Coil shapes for solenoids, dipoles & quadrupoles  /  Engineering current density & load lines  /  Degradation, training & minimum quench energy MQE  /  Flux jumping  /  

Quenching and Protection:  The quench process  /  Resistance growth, current decay, temperature rise  /  Calculating the quench  /  Mini tutorial on quenching  /  Quench protection schemes                                    

Cryogenics & Practical Matters:  Working fluids, refrigeration  /  Cryostat design  /  Current leads  /  Accelerator magnet manufacture  /  Some superconducting accelerators

 

Particle sources

Particle sources. The course will review the different type of particle sources and their productions:

Eelectron-emission properties (thermal emission, field emission, photon induced emission)  /  Electron sources and positron source

Introduction to ion production and some basic concepts

Different kind of ion sources: proton/1+ -ion sources, H- -ion sources  /  Sources for highly charged ions  /  Radioactive ion beams

Low energy electron accelerators

 

Accelerators for industrial and medical applications

After a brief introduction to the IBA company, a first part of the course deals with the use of radio-isotopes for medical applications. Both medical imaging and brachy-therapy are discussed

A second part of the course discusses the use of cyclotrons for radioisotope production. Aspects like magnetic design, central region design, internal versus external ion sources, magnetic field mapping and beam extraction are covered. Also some features of targets for radioisotopes are shown

A third part of the course deals with particle therapy of cancer. The main requirements and the main sub-systems of the proton-therapy facility are explained. The solution of cyclotrons for proton and carbon therapy is covered and the latest development of superconducting synchrocyclotrons for proton-therapy is looked at in some detail

A fourth part of the course discusses some typical electron accelerators that are used for industrial applications such as the rhodotron and the dynamitron

 

Lyfe-cycle and reliability of particle accelerators

The “life” of a particle accelerator is made of several steps from early stages of expression of interest to dismantlement. 

Beyond the classical periods study-fabricate-install-test-operate-maintain, we will look at the associated links customer/supplier and the surroundings fields, such as the building. 

In a second part, the subject of “reliability” will be used to illustrate several mechanisms occurring during the life-cycle of an accelerator.

 

Radiation Oncology : biology, physics and clinical applications

The course aims to present in a structured and summarized way the basics of radiation oncology to treat cancer, especially the biological and physical fundamentals, with present and future perspectives of optimization mostly through technological progress and imaging developments, the latter allowing for an optimal accuracy in the definition of target volumes.

If 3-D dose sculpting around the tumour is the goal, in order to reach it, a perfect organ immobilization and patient positioning reproducibility are needed. Image guided radiotherapy (IGRT) techniques are the best support to overcome such limiting factors.

In addition, a safety margin reduction around the target can be performed with on-line IGRT monitoring during treatment thus reducing the risk of toxicity when high doses to the tumour need to be delivered.

Treatment precision with 3-D conformal RT techniques employing either intensity modulated RT (IMRT) with X-rays or proton beams may deliver almost exclusively ultra-high doses to the tumour potentially improving local control and cure rates while simultaneously reducing morbidity. 

 

High current proton linacs

High power proton beams are required for a very large variety of applications in nuclear physics, particle physics, neutrons and material science, nuclear waste treatment…

Many facilities are under project or construction worldwide and are facing several challenges.

In this course, we will review the different applications of high power beams and the corresponding existing facilities or ongoing projects, then address the basic principles of these accelerators and finally present the main issues and challenges to deal with these very high power beams.

 

Radiation safety

Basic principles of radiation physics and radiation protection rules: the different ionizing radiation sources of importance around accelerators and their interactions with matter  /  The shielding of electron accelerators, proton accelerators and synchrotron beamlines  /  Radiation monitoring

Personnel safety systems

Prerequisites: knowledge of basic mathematics; basic knowledge about accelerators