Rf superconductivity for accelerators, wiley publishers 1998, by hasan padamsee, jens knobloch and tom hays. More recently, the truebeam class linear accelerator by varian has a mode of operation with. Some medical and industrial applications employ the resulting accelerated highenergy particle beams. The field in the gap oscillates with time at a given rf. Linacs have an advantage of better beam quality, an output beam focus with smaller size. For a proton synchrotron, the injected beam is not yet relativistic, so the rf accelerating frequency and the magnetic field both. We shall concentrate our study on them, leaving out devices such as. Because the phase velocity of the rf wave is larger than the. So linear accelerators were not pursued heavily at that time. Rf noise from clinical linear accelerators 2485 due to the different rf source to measurement point distances, the sources of rf noise are subject to different shielding effects. Recently, triode rf gun based injection systems are frequently used 3,4.
Massachusetts institute of technology rf cavities and components for accelerators uspas 2010. The short lecture introduced the student s to rf specifics and beam dynamics basics giving them a good understanding of linacs. This book provides a concise and coherent introduction to the physics of particle accelerators, with attention being paid to the design of an accelerator for use as an experimental tool. Lecture 1 varieties of accelerators particle sources,linear. A proofofprinciple of the phase control of an injection. Less rf energy per pulse is required, so fewer rf components. Itconsisted in a itconsisted in a vacuum tube containing a cathode connected to the negative pole of a dc voltage generator. Since that time, a sizable number of linear accelerators, also called linacs, have come into operation, both for electron and proton acceleration, as well as several heavyion linacs. A compact superconducting rf accelerator for electron beam. A basic circuit of a linear accelerator pulsing system is shown in figure 3 and consists of a high voltage supply e, which is used to charge the pulseforming network pfn. Aug 02, 2012 proton linear accelerator institute plai of the nanjing university was established in october of 2011. The concept most applicable for the accelerators is the powering of each srf cavity by an individual vector controlled rf source providing a control of phase and of power. Radiofrequency linear accelerators 438 frequency rf is usually applied to resonant accelerators, it is somewhat misleading. The abstract cern, geneva, switzerland mario weiss introduction to rf linear accelerators.
Rf electron linac is introduced in this lecture note, including the principles of acceleration, their basic features, main structures, preinjector, longitudinal and transverse motions, and beam physics for a high current and high energy injector linac. Hansen,3 and the idea for a proton linear accelerator was started under l. A brief history of high power rf proton linear accelerators. Particle generatorsaccelerators european commission.
A suitable mathematical model for the power output from the system p kly was found to be. Linear accelerators principles, history, and applications. In general, the aim is to transfer energy from the rf wave to electron beam consisting of bunches of charged particles. Activities of superconducting rf accelerators at nanjing. Simulation of a medical linear accelerator for teaching. Vrentinar linear accelerators cern accelerator school. A linear particle accelerator often shortened to linac is a type of particle accelerator that accelerates charged subatomic particles or ions to a high speed by subjecting them to a series of oscillating electric potentials along a linear beamline. Such devices are very important and are called in fact, we wish to be even more restrictive and only consider devices which operate with. References about subsystems of a linear accelerator linear accelerators for radiation therapy, 2nd edition.
Rf systems for accelerators us particle accelerator school. Avoided size problem of linear accelerators, early ones few mev 4 70 kev protons. Lecture 9 linear accelerators and rf systems case stony brook. Pdf on jan 1, 2005, nicolas pichoff published introduction to rf linear accelerators find, read and cite all the research you need on researchgate. This transmitter is proposed to drive superconducting rf srf cavities for intensityfrontier gevscale protonion linacs, such as the projected fermilab proton linacs or linacs for accelerator driven system ads. Radio frequency system klystronsbelong to the class of tubes called linear beam tubes. Introduction an electron gun with appropriate injection system is a significant part of any rf linear electron accelerator 1,2. The course will address both physics and engineering aspects of the field. The concept of the loaded cavity, essential for the synchronism waveparticle, is introduced, and formulae describing the action of elec tromagnetic fields on the beam are given. A onehour lecture on rf linear accelerators linacs and a tenhour course were given to the cas students. Lowlevel rf control of a klystron for medical linear. Cyclotrons, synchrotrons and their variants linear accelerators use many cavities through which the particle passes only once. A wave with an oblique incidence on a conducting plane is shown in fig. The attractiveness of magnetrons as rf sources for linear accelerators is obvious.
Continuouswave electron linear accelerators for industrial. However, further research in this direction was set aside. The text provides the scientific principles and uptodate technological aspects for both electron and ion linacs. Electrons emitted by the heated cathode were accelerated while flowing to another electrode connected to the positive generator pole anode. Rf linear accelerators, 2nd, completely revised and enlarged. Frequency rf cavities v e e e e v circular accelerators use one or a small number of rf cavities and make use of repeated passage through them. Dc accelerators are limited by a maximum size and a maximum break down voltage by using a time varying field and adding drifts that are matched in circular accelerator linear accelerator by using a time varying field and adding drifts that are matched in length to the growing velocity of the particles and rf frequency, one can. The first historical linear particle accelerator was built by the nobel prize wilhelm conrad rontgen 1900. Introduction to rf linear accelerators mario weiss cern, geneva, switzerland abstract the basic features of rf linear accelerators are described. We will use a proton linear accelerator as proton beam producer with different energy output. The main problem in generating con tinuous electron beams using normal conducting nc linacs is low pace of energy gain and high level of rf. The physics and technology of ion sources 2004 isbn. A 2mwpulse tube operates at a relatively low voltage, 40.
Depending on the facility, an experiment or application is carried out at the output of the linac, or the particles are injected into a booster ring e to be accelerated further. Longitudinal and transverse dynamics in linacs dr graeme burt lancaster university some elements from wangler, rf linear accelerators, s. Although some resonant linear accelerators have been constructed with very large or inductive structures, most present accelerators use resonant cavities or waveguides with dimensions less than 1 m to. A linear accelerator is disclosed, having a series of interconnected cavities through at least some of which an rf signal and an electron beam are sent, comprising at least one variable coupler projecting into the a cavity of the series, a control apparatus adapted to interpret an electrical signal from the coupler and derive diagnostic information as to the electron beam therefrom, wherein. A proofofprinciple of the phase control of an injectionlocked magnetron first has been demonstrated with. Nov 21, 2008 rf linear accelerators is a textbook that is based on a us particle accelerator school graduatelevel course that fills the need for a single introductory source on linear accelerators. Superconductivity and cryogenics for accelerators and detectors cas cern accelerator school, may 2002. Introduction to rf linear accelerators maurizio vretenar maurizio vretenar cern abrfcern ab rf 1. This paper deals with the notions introduced in the lecture. In the second edition, new chapters on spin dynamics of polarized beams as well as instrumentation and measurements are included, with a discussion of. The goal of a particle accelerator is to obtain a required beam within the. Two types of electron gun are in use in medical linacs. The history of linear accelerators is briefly described by j.
This graduate level course covers application of radio frequency rf superconductivity to contemporary particle accelerators. This is provided by a low power oscillator typically called an rf driver. Superconductivity in particle accelerators cas cern accelerator school, may 1995. In this work, the preliminary design of an electron linear particle accelerator. Feb 12, 2019 an rf linear accelerator linac for applications in the medical field is a device that uses electromagnetic waves, in the microwave range, to accelerate charged particles such as electrons. An rf linear accelerator is made of a sequence of accelerating elements. Lecture 1 varieties of accelerators particle sources. An introduction to the physics of particle accelerators. Rf linear accelerators, 2nd, completely revised and. The effect of nonlinear forces on emittance growth is introduced. The particles are propelled up to speed in a linear accelerator linac w.
More precise information can be found in the cas dedicated to rf 3. Study of the first mexican rf linear accelerator scielo. Distance between gaps increases proportionally to the particle velocity, to keep synchronicity. Rf system overview cadolphsen slac national accelerator. Rf linacs are used for a wide spectrum of applications from injectors into circular accelerators, to entire highenergy accelerators such as slac, medical accelerators, and many others.
Particles accelerated by a sequence of gaps all at the same rf phase. Simulation of a medical linear accelerator for teaching purposes. They typically operate at over 60% efficiency at uhf and lband frequencies. As the cost of the rf gene rally represents the main expense of the linac structure apart from the building, the choice of the rf structure has to be studied very carefully. Diode type triode type both electron gun types contain. If we inject the rf into a waveguide then on average, a electron beam traversing the waveguide gains no energy from the e. Why linear accelerators basic concepts 2 periodic accelerating structures2. This paper presents only the principle of an rf cavity.
The accelerating structure depends on the type of linac. They are an oscillator, hence no drive system is required. Rf linear accelerators is a textbook that is based on a us particle accelerator school graduatelevel course that fills the need for a single introductory source on linear accelerators. Energy 100 mev rf cavities 2 rf frequency 2996 mhz repetition rate 1 khz beam current 400 ma fodo cells per line 3, 3, 1 magnetic gradient 10 mev 0. Invention of synchrotrons was important for linacs since synchrotrons need linac injectors.
Reasonable efficiencies are achievable at higher gradients, so linac shorter. In most linac applications, the klystron is used as an amplifier, so an input signal is required. Treatment machines for external beam radiotherapy, chapter 5 in radiation oncology physics. Tighter alignment constraints due to stronger wakefields. Jan 23, 2008 rf linear accelerators, second edition. The design accelerator gradient is 65 mvm unloaded 52 mvm loaded and the rf pulse length is 400 ns 2. The transmitter consists of two 2cascade injectionlocked magnetrons with outputs combined by a. A compact superconducting rf accelerator for electron. The basic features of rf linear accelerators are described. Research continued during the 1930s but the development of high frequency rf tubes for radar applications in world war 2 opened the potential for rf linear accelerators after the war. Particle acceleration in linear accelerators as well as in circular accelerators are based on the use of rf fields and we will in the following sections and in the next chapter discuss the principles of the more important types of particle accelerators.
Rf linac based very high energy ion implanter capable of maximum energies of up to 8mev for phosphorus and arsenic. In conclusion, a software tool, named simac, was developed to improve the teaching of linear accelerator physics in a simulated environment. Development of pulsed rf power sources at hundreds of mhz and with megawatts of power removed the technical barrier for electron and proton linacs. Highpower magnetron transmitter as an rf source for. Linear and circular accelerators linear accelerator. Superconducting rf for storage rings, erls and linac based fels by s.
After the war, the idea for the stanford linear accelerator was born under w. All accelerators produce the particles in a particle source q. Radiofrequency pulse compression for linear accelerators christopher dennis nantista stanford linear accelerator center stanford university, stanford, ca 94309 january 1995 prepared for the department of energy under contract number deac0376sf00515 printed in. In order to accelerate, each element has to generate an electric field in the region crossed by the beam, usually consisting of a gap between two metallic plates fig. Itconsisted in a vacuum tube containing a cathode connected to the negative pole of a dc voltage generator. Linear accelerator electrostatic field drift tube electrostatic accelerator electrostatic generator.
481 255 1341 757 698 757 1387 417 494 1719 4 1248 372 1610 1292 1238 968 275 751 1651 1226