Storage Ring Technology Research Articles

Diffraction-limited storage-ring vacuum technology.

Some of the characteristics of recent ultralow-emittance storage-ring designs and possibly future diffraction-limited storage rings are a compact lattice combined with small magnet apertures. Such requirements present a challenge for the design and performance of the vacuum system. The vacuum system should provide the required vacuum pressure for machine operation and be able to handle the heat load from synchrotron radiation. Small magnet apertures result in the conductance of the chamber being low, and lumped pumps are ineffective. One way to provide the required vacuum level is by distributed pumping, which can be realised by the use of a non-evaporable getter (NEG) coating of the chamber walls. It may not be possible to use crotch absorbers to absorb the heat from the synchrotron radiation because an antechamber is difficult to realise with such a compact lattice. To solve this, the chamber walls can work as distributed absorbers if they are made of a material with good thermal conductivity, and distributed cooling is used at the location where the synchrotron radiation hits the wall. The vacuum system of the 3 GeV storage ring of MAX IV is used as an example of possible solutions for vacuum technologies for diffraction-limited storage rings.

Technical Report: The Status of the Energy Recovery Linac Source of Coherent Hard X-rays at Cornell University

Synchrotron radiation research as a field is still in a growing phase because newer and more capable X-ray sources are presently under development. Advances in storage ring technology, as explained in the Guest Editorial for this special New Source issue by Kwang-Je Kim, is rapidly approaching the point of diminishing returns. It is expected that within a few years storage ring technology will have matured to the point where it will become exceptionally difficult and expensive to make further significant improvements to the X-ray beam quality. In contrast, linac-based sources such as energy recovery linacs (ERLs) and X-ray free electron lasers (XFELs) are at an early stage of development, and provide a clear path for dramatically improving X-ray beam qualities that is likely to continue for many years. ERLs promise to generate bright electron beams, and thus X-rays, with dramatically smaller emittances and pulse durations than those available from storage rings, the present workhorse technology for all existing hard X-ray synchrotron radiation sources. As described in the companion X-ray Free Electron Laser (XFEL) article, new opportunities also exist in a complimentary direction, namely, that of making a lower duty factor X-ray laser that will also generate exciting new science. Though both ERL1 and the XFEL2 technologies have considerable promise as future Xray sources, much development work and learning in both accelerator and X-ray technology will be required to realize their potential.

Synchrotron X-Ray Microfluorescence and Microspectroscopy: Application and Perspectives in Materials Science

Recent developments in synchrotron storage ring technology, insertion device design and X-ray optics provide polarized photon beams with unprecedented intensity and brilliance on a microscopic area. Various arrangements allow micrometer size hard X-ray beams with enough flux to undertake elemental mapping of trace elements then easily associated with micro-diffraction or micro-extended X-ray absorption fine structure studies on the very same sample region of interest. These analytical possibilities and the sensitivity and accuracy of the achieved analysis can complement or surpass other available instrumental micro-analytical methods. Such microprobes are becoming a very interesting tool for material characterization.

Future applications of science with synchrotron radiation and free-electron lasers in Europe

Future applications of science with synchrotron radiation and free-electron lasers in Europe

Experiments on cooled molecular ions

Ion storage ring technology allows molecular ions to be accelerated to MeV energies and stored for tens of seconds in an ultra-high vacuum ring system. By merging the ion beam with a cold electron beam in one section of the ring, a phase-space cooled ion beam with low divergence and low momentum spread is obtained. Infrared active molecular ions are also vibrationally cooled by spontaneous emission of radiation. A stored ion beam of this quality is ideal for studies of molecular processes such as dissociative recombination.

Commercially designed and manufactured storage ring for synchrotron radiation applications

Electron storage ring technology is now some twenty-odd years old and is both well-advanced and accepted. As a natural consequence, the commercial manufacture of such machines is becoming a reality. This paper describes the design of what is to be the first industrially manufactured electron storage ring in the United States. As such, the design represents an outstanding example of technology transfer from US national laboratories into the private sector. The design described in this paper, for the Center for Advanced Microstructures and Devices (CAMD) facility at Louisiana State University (LSU) [B.C. Craft et al., Nucl. Instr. and Meth. B40/41 (1989) 379; R.L. Stockbauer et al., these Proceedings, p. 505], features “low energy” injection, at 200 MeV, which is only a fraction of the 1.4-GeV peak energy. Nominal operation will be at 1.2 GeV with a beam current of 400 mA and an emittance of 2 × 10 −7π m rad. The corresponding value of critical wavelength is λ c = 9.5 A ̊ .

UNDERSTANDING MODERN MAGNETS THROUGH CONFORMAL MAPPING

When I had to choose, within some narrow range, the topic of this paper, I received great help from a colleague in Berkeley and from Prof. Little when it was suggested that I should pick among the possible subjects of my talk the subject that Prof. Bloch would have enjoyed most. Since Prof. Bloch would prefer a scalpel over a sword every time, I hope and think that most people will approve my choice. When one intends to talk about a subject that is as old as conformal mapping and one does not want to lose the audience in a very short time, it is advisable to start by explaining both the motivation for the talk as well as the goals one has in mind when giving the talk. This particular talk has been motivated by the increasing frequency with which one hears, from people that ought to know better, statements like: 'Conformal mapping is really a thing of the past because of all the marvelous computer programs that we now have'. Even though, or more likely because, I have been intimately involved in the development of some large and widely used computer codes, I am deeply disturbed by such more » statements since they indicate a severe lack of understanding of the purpose of conformal mapping techniques, computers, and computer codes. In my view, conformal mapping can be an extremely powerful computational technique, and the easy availability of computers has made that aspect even more important now than it has been in the past. Additionally, and more importantly, conformal mapping can give very deep and unique insight into problems, giving often solutions to problems that can not be obtained with any other method, in particular not with computers. Wanting to demonstrate in particular the latter part, I set myself two goals for this talk: (1) I want to show with the help of a number of examples that conformal mapping is a unique and enormously powerful tool for thinking about, and solving, problems. Usually one has to write down only a few equations, and sometimes none at all. When I started getting involved in work for which conformal mapping seemed to be a powerful tool, I did not think that I would ever be able to use that technique successfully because it seemed to require a nearly encyclopedic memory, an impression that was strengthened when I saw H.Kober's Dictionary of Conformal Representations (ref. 1). This attitude changed when I started to realize that beyond the basics of the theory of a function of a complex variable, I needed to know only about a handful of conformal maps and procedures. Consequently, my second goal for this talk is to: (2) Show that in most cases conformal mapping functions can be obtained by formulating the underlying physics appropriately. This means particularly that encyclopedic knowledge of conformal maps is not necessary for successful use of conformal mapping techniques. To demonstrate these facts I have chosen examples from an area of physics/engineering in which I am active, namely accelerator physics. In order to do that successfully I start with a brief introduction into high energy charged particle storage ring technology, even though not all examples used in this paper to elucidate my points come directly from this particular field of accelerator technology. This is followed by a brief summary of the most important properties of functions of a complex variable. When reading this introduction into the relevant mathematics, the reader needs to keep in mind that this is not a mathematics essay, but a demonstration how beautiful and powerful, but not always appreciated, mathematics can be if used by a physicist or engineer to solve some real life problems. « less

Implications for a short wavelength laser experiment based on a theory of quasi-channeling phenomenon for electrons

The theory of electron and positron channeling and radiation production in crystals has been extended to macroscopic-scale systems. The new theory, named QCP theory (quasi-channeling phenomenon), examines macroscopic systems that exhibit periodicity along the axis of beam propagation, specifically, periodic electrostatic fields; the dimensions of the field periodicity (lz) are much greater than typical interatomic lattice spacing (lL), e.g., lz≫lL, but much smaller than a typical wiggler wavelength lw, e.g., lw≫lz. The feasibility of a laser based on this predicted new phenomenon is examined in this letter. Differences between the properties of the proposed quasi-channeling radiation and radiation produced by wigglers and free-electron lasers (FEL’s) are discussed. System lengths a factor of 103 shorter than FEL’s are expected, with favorable scaling for below 500 eV laser photon output energies. A 500-eV QCP laser system with a gain of 1 and a length of 1 m is predicted, based on extrapolations of existing storage-ring technology.

Issues in storage-ring design for operation of high-gain FEL

A high-gain free electron laser (FEL), placed in a special by-pass of a storage ring, can provide tens of megawatts of coherent power at wavelengths shorter than 1000 Å. The requirements on beam quality (few hundred amperes of peak current, emittance of the order of 10 −8 m·rad, and relative energy spread less than 0.002), are demanding but lie within the limits of modern storage ring technology. In this paper, we study various issues in storage ring design and FEL physics for operation of a high-gain FEL. Topics included are the requirements on beam parameters for FEL operation, coherent instabilities and intrabeam scattering effects in the storage ring, lattice design, and FEL performance computed by 2-D simulations.

Stanford linear collider scheduled to operate in 1986

Construction of the Stanford Linear Collider is well under way. The SLC is the crucial testing ground of a new accelerator technology, widely thought to be indispensible if we are to push electron–positron collision energies much beyond what LEP will make available. LEP, the Large Electron–Positron storage ring under construction at CERN, near Geneva, is scheduled to provide e+e− collision energies of 100 GeV by the beginning of 1989. But this gargantuan $400-million ring, 27 km in circumference, is regarded by many as the largest practicable e+e− collider one can base on the well-tried storage-ring technology. Significantly higher e+e− energies, it is believed, will require linear colliders.