Statistical Properties Of Undulator Radiation

This thesis presents significant advances in the understanding of the statistical properties of undulator radiation via two experiments carried out in the Integrable Optics Test Accelerator (IOTA) storage ring at Fermilab. The first experiment studied the turn-to-turn fluctuations in the power of the radiation generated by an electron bunch. The magnitude of these fluctuations depends on the 6D phase-space distribution of the electron bunch. The author presents the most complete theoretical description of this effect to date, and shows that it can be used to measure some electron bunch parameters (e.g. its size and divergence). Remarkably, the performance of this technique improves for smaller bunches and shorter radiation wavelengths and it may, therefore, be particularly beneficial for existing state-of-the-art and next-generation low-emittance high-brightness x-ray synchrotron light sources. In the second experiment, a single electron was stored in the ring, emitting a photon only once per several hundred turns. In this regime, any classical interference-related collective effects were eliminated, and the quantum fluctuations could be studied in detail to search for possible deviations from the expected Poissonian photon statistics. In addition, the photocount arrival times were used to track the longitudinal motion of a single electron and to compare it with simulations. This served as an independent measurement of several dynamical parameters of the storage ring.

This thesis presents significant advances in the understanding of the statistical properties of undulator radiation via two experiments carried out in the Integrable Optics Test Accelerator (IOTA) storage ring at Fermilab. The first experiment studied the turn-to-turn fluctuations in the power of the radiation generated by an electron bunch. The magnitude of these fluctuations depends on the 6D phase-space distribution of the electron bunch. The author presents the most complete theoretical description of this effect to date, and shows that it can be used to measure some electron bunch parameters (e.g. its size and divergence). Remarkably, the performance of this technique improves for smaller bunches and shorter radiation wavelengths and it may, therefore, be particularly beneficial for existing state-of-the-art and next-generation low-emittance high-brightness x-ray synchrotron light sources. In the second experiment, a single electron was stored in the ring, emitting a photon only once per several hundred turns. In this regime, any classical interference-related collective effects were eliminated, and the quantum fluctuations could be studied in detail to search for possible deviations from the expected Poissonian photon statistics. In addition, the photocount arrival times were used to track the longitudinal motion of a single electron and to compare it with simulations. This served as an independent measurement of several dynamical parameters of the storage ring.

This open access book is devoted to the theoretical and experimental studies of a novel accelerator light source mechanism called steady-state microbunching (SSMB) which promises high-power, high-repetition rate, narrow-band coherent radiation in an electron storage ring. The contribution of this dissertation consists of three parts: first, answers the question of how to realize SSMB from a beam dynamics perspective; second, reveals what radiation characteristics can we obtain from the formed SSMB; and third, experimentally demonstrates the working mechanism of SSMB in a real machine for the first time. The highlights of this book can be summarized as: Presents the first proof-of-principle experiment of a promising accelerator light source mechanism; Covers precision longitudinal and transverse-longitudinal coupling dynamics in a storage ring; Provides useful formulas and example parameters for high-power infrared, EUV and soft X-ray light source design.

This book contains the Proceedings of the 24th International Free Electron Laser Conference and the 9th Free Electron Laser Users Workshop, which were held on September 9-13, 2002 at Argonne National Laboratory. Part I has been reprinted from Nucl. Instr. and Meth. A 507 (2003), Nos. 1-2.

The high scienti?c interest in coherent X-ray light sources has stimulated world-wide e?orts in developing X-ray lasers. In this book a particularly promising approach is described, the free-electron laser (FEL), which is p- sued worldwide and holds the promise to deliver ultra-bright X-ray pulses of femtosecond duration. Other types of X-ray lasers are not discussed nor do we try a comparison of the relative virtues and drawbacks of di?erent concepts. The book has an introductory character and is written in the style of a universitytextbookforthemanynewcomerstothe?eldoffree-electronlasers, graduate students as well as accelerator physicists, engineers and technicians; it is not intended to be a scienti?c monograph for the experts in the ?eld. Building on lectures by one of us (J. R.) at the CERN Accelerator School, and motivated by the positive response to a series of seminars on “FEL t- ory for pedestrians”, given by P. S. within the framework of the Academic Training Program at DESY, we have aimed at presenting the theory of the low-gainandthehigh-gainFELinaclearandconcisemathematicallanguage. Particular emphasis is put on explaining and justifying the assumptions and approximations that are needed to obtain the di?erential equations descr- ing the FEL dynamics. Although we have tried our best to be “simple”, the mathematical derivations are certainly not always as simple as one would like them to be. However, we are not aware of any easier approach to the FEL theory. Some of the more involved calculations are put into the appendices.

The main goal of the book is to provide a systematic and didactic approach to the physics and technology of free-electron lasers. Numerous figures are used for illustrating the underlying ideas and concepts and links to other fields of physics are provided. After an introduction to undulator radiation and the low-gain FEL, the one-dimensional theory of the high-gain FEL is developed in a systematic way. Particular emphasis is put on explaining and justifying the various assumptions and approximations that are needed to obtain the differential and integral equations governing the FEL dynamics. Analytical and numerical solutions are presented and important FEL parameters are defined, such as gain length, FEL bandwidth and saturation power. One of the most important features of a high-gain FEL, the formation of microbunches, is studied at length. The increase of gain length due to beam energy spread, space charge forces, and three-dimensional effects such as betatron oscillations and optical diffraction is analyzed. The mechanism of Self-Amplified Spontaneous Emission is described theoretically and illustrated with numerous experimental results. Various methods of FEL seeding by coherent external radiation are introduced, together with experimental results. The world’s first soft X-ray FEL, the user facility FLASH at DESY, is described in some detail to give an impression of the complexity of such an accelerator-based light source. The last chapter is devoted to the new hard X-ray FELs which generate extremely intense radiation in the Angstrøm regime. The appendices contain supplementary material and more involved calculations.

The 22nd International Free Electron Laser Conference and 7th FEL User Workshop were held August 13-18, 2000 at Washington Duke Inn and Golf Club in Durham, North Carolina, USA. The conference and the workshop were hosted by Duke University's Free Electron laser (FEL) Laboratory. Following tradition, the FEL prize award was announced at the banquet. The year 2000 FEL prize was awarded to three scientists propelling the limits of high power FELs: Steven Benson, Eisuke Minehara and George Neill. The conference program was comprised of traditional oral sessions on First Lasing, FEL theory, storage ring FELs, linac and high power FELs, long wavelength FELs, SASE FELs, accelerator and FEL physics and technology, and new developments and proposals. Two sessions on accelerator and FEL physics and technology reflected the emphasis on the high quality of accelerators and components for modern FELs. The breadth of the applications was presented in the workshop oral sessions on materials processing, biomedical and surgical applications, physics and chemistry as well as on instrumentation and methods for FEL applications. A special oral session was dedicated to FEL center status reports for users to learn more about the opportunities with FELs. As usual, the oral sessions were supplemented by poster sessions with in-depth discussions and communications. The FEL physicists and FEL users had excellent opportunities to interact throughout the duration of the event, culminating a Joint Sessions. The year 2000 was very successful being marked by lasing with two SASE and one storage ring short-wavelength FELs, and by the first human surgery with the use of FEL, to mention but a few. The International Program Committee and chairs of the sessions had the challenging and exciting problem of selecting invived and contributed talks for the conferences and the workshop from the influx of abstracts mentioning new results and ideas. The success of the conference was determined by these contributions. Scientists from 15 countries gave 70 talks, presented 176 posters and submitted 146 papers, which are published in the present volume of proceedings.

This volume contains Part II of the proceedings of the conference on Free Electron Lasers, held in Beijing, August 1997. Part I appears in a special issue of Nuclear Instruments and Methods A. The last 20 years has seen different stages of FEL development. In these proceedings the reader will find descriptions of many new facilities, new experimental results, new applications, new theoretical developments and new simulation results. Attention is also focussed on the recent progress in experimental observations SASE. The contributions are from 150 scientists from 13 countries, ensuring broad, up-to-date research results from a dynamic field.