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in creator/contributor: "Kim, K. J."

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Three-dimensional free electron laser dispersion relation including betatron oscillations

We have developed a 3-D FEL theory based upon the Maxwell-Vlasov equations including the effects of the energy spread and emittance of the electron beam, and of betatron oscillations. The radiation field is expressed in terms of the Green's function of the inhomogeneous wave equation and the distribution function of the electron beam. The distribution function is expanded in terms of a set of orthogonal functions determined by the unperturbed particle distribution. The coupled Maxwell-Vlasov eq… more

Date: August 1, 1991

Creator: Chin, Y. H.; Kim, K. J. & Xie, M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Partially coherent x-rays from modern storage rings

Several routes to the development of ideal soft x-ray sources are now being actively pursued. These include atomic lasers, free electron lasers (FELs), and storage ring (synchrotron) undulators. For short wavelength (XUV) applications, FELs and undulators are very closely related, each being dependent on the development of well controlled (low ''emittance'') electron storage rings, with energies of order 0.5 to 1.5 GeV beam energy, and many period magnetic structures, referred to as undulators.… more

Date: November 1, 1984

Creator: Attwood, D.; Halbach, K. & Kim, K. J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Some effects of the transverse-stability requirement on the design of a grating linac

The transverse stability of the grating linac proposed by Palmer is analyzed. It is shown that an open structure such as a grating is always unstable transversely as long as it is uniform. The structure can be made stable by utilizing the strong focusing principle. This is achieved by periodically interrupting the grating shape. We analyze the strong focusing grating linac, and find that the stability requirement places a non-trivial constraint on the phase acceptance of the system.

Date: April 1, 1982

Creator: Kim, K. J. & Kroll, N. M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Three-dimensional simulation of a hole-coupled FEL oscillator

The performance of a two-mirror resonator with holes for out-coupling has been examined in a previous study in which the FEL gain was neglected, but the geometrical effect of the wiggler aperture was included in the optical calculation. The phenomenon of mode degeneracy was found to occur, that has serious implications for the stability of performance when the FEL gain is included. We have developed a FEL oscillator code based on TDA'', a three-dimensional FEL amplifier code, to study the mode … more

Date: August 1, 1991

Creator: Krishnagopal, S.; Xie, M.; Kim, K. J. & Sessler, A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Design concepts of a storage ring for a high power XUV free electron laser

The study of a storage ring capable of sustaining an electron beam of the quality required for a High Gain Free Electron Laser in the vacuum ultraviolet and x-ray region is reported. A method is described for the optimization of the design of the storage ring, where several competing and often conflicting requirements come into play. An example design is presented of a ring that satisfies the required conditions of beam quality and is able to produce coherent radiation at 400 A with tens of meg… more

Date: August 1, 1985

Creator: Cornacchia, M.; Bisognano, J.; Chattopadhyay, S.; Garren, A.; Halbach, K.; Jackson, A. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Photon storage cavities

A general analysis is presented of a photon storage cavity, coupled to free-electron laser (FEL) cavity. It is shown that if the coupling between the FEL cavity and the storage cavity is unidirectional (for example, a ring resonator storage cavity) then storage is possible, but that if the coupling is bi-directional then storage is not possible. Parameters are presented for an infra-red FEL storage cavity giving an order of magnitude increase in the instantaneous photon power within the storage… more

Date: August 1, 1991

Creator: Kim, K. J. & Sessler, A. M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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High-gain free electron lasers as generators of short wavelength coherent radiation

The development of coherent radiation in high-gain free electron lasers, either from initial noise or from low-power input radiation, is analyzed in terms of three-dimensional Maxwell-Klimontovich equations. Exponential growth and saturation, transverse radiation profiles, transverse coherence and spectral features are discussed. Two possible systems of high-gain free electron lasers, one based on a storage ring and by-pass, another based on a linac and damping rings, are considered for the gen… more

Date: May 1, 1986

Creator: Kim, K. J. & Pellegrini, C.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Free electron laser with versatile polarization capability

A novel configuration of free electron laser system is proposed that is capable of generating coherent radiation whose polarization is arbitrary and rapidly adjustable. The magnet configuration is similar to that of the optical klystron except that the undulators are placed perpendicular rather than parallel to each other. The gain of the system is analyzed in the small signal regime, and is found to be similar to that of the optical klystron. The polarization of the laser radiation at maximum … more

Date: September 1, 1983

Creator: Kim, K. J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Free-Electron Lasers: Present Status and Future Prospects

Free-electron lasers as scientific instruments are reviewed. The present status and future prospects are delineated with attention drawn to the size, complexity, availability, and performance capability of this new tool. The Free-Electron Laser (FEL) was proposed by John Madey in 1970 (1), although earlier work, relevant to the concept, had been performed by Motz (2) and by Phillips (3). Experimental demonstration was achieved by Madey, et. al. in 1975 and 1976 (4). Since that time, FELs of div… more

Date: May 1, 1990

Creator: Kim, K. J. & Sessler, Andrew M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Generation of Femtosecond X-Rays by 90 degrees Compton Scattering

We propose Compton scattering of a short pulse visible laser beam by a low energy (but relativistic) electron beam at a right angle for generation of femtosecond x-rays. Simple analysis to determine the qualitative and quantitative characteristics of the x-ray pulse is presented.

Date: December 1, 1992

Creator: Kim, K. J.; Chattopadhyay, S. & Shank, C. V.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Polarized nature of synchrotron radiation

Synchrotron radiation is inherently highly polarized, and this fact makes synchrotron radiation useful for probing the directional and/or helical nature of the matter via polarization sensitive experiment. Here we summarize briefly the nature of the polarization experiments and the polarization characteristics of synchrotron radiation. 12 refs., 3 figs.

Date: September 1, 1991

Creator: Kim, K. J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Evolution of the radiation-beam system in long undulators

The process by which the radiation intensity grows and correlation in the electron distribution develops, as the beam passes through a long undulator, is described.

Date: November 1, 1985

Creator: Kim, K. J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Stability and performance of CDRL-FEL (Chemical Dynamics Research Laboratory-Free Electron Laser)

We study the performance of a proposed infrared free electron laser at Lawrence Berkeley Laboratory, which would be a user facility and therefore has a unique set of requirements in intensity, spectrum and stability. The output performance in intensity and spectrum, and methods to optimize the performance, are studied in detail. The effect of the electron beam fluctuation on FEL stability is carefully evaluated to set a tolerance for the accelerator design. Use of intracavity gratings is studie… more

Date: November 1, 1990

Creator: Kim, K. J. & Xie, M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Issues in storage-ring for operation of high-gain FELs

A high-gain free electron laser (FEL), placed in a special by-pass of a storage ring, can provide tens of magewatts of coherent power at wavelengths shorter than 1000 A. The requirements on beam quality, (few hundred amperes of peak current, emittance of the order of 10/sup -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… more

Date: December 1, 1984

Creator: Kim, K. J.; Bisognano, J. J.; Garren, A. A.; Halbach, K. & Peterson, J. M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Study of microwave instabilities by means of a squarre-well potential

Microwave instabilities are analyzed in a simple model in which the usual synchroton oscillation of a particle is replaced by particle motion in a square well potential. In this way the previous difficulties in the theory complexity disappear. The model is precisely defined, solved, and the properties of the solution are discussed. 5 references. (JFP)

Date: September 1, 1979

Creator: Kim, K. J.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Polarization characteristics of synchrotron radiation sources and a new two undulator system

The polarization properties of the usual synchrotron radiation sources are briefly reviewed. The recently proposed two undulator system can provide synchrotron radiation with arbitrarily adjustable polarization. The characteristics of this device both as a source of spontaneous radiation and also as a free electron laser system are discussed.

Date: September 1, 1983

Creator: Kim, K. J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Beam Line VI REC-steel hybrid wiggler for SSRL

A wiggler magnet with 27 periods, each 7 cm long which reaches 1.21 T at a 1.2 cm gap and 1.64 T at 0.8 cm gap has been designed and is in fabrication. Installation in SPEAR is scheduled for mid 1983. This new wiggler will be the radiation source for a new high intensity synchrotron radiation beam line at SSRL. The magnet utilizes rare-earth cobalt (REC) material and steel in a hybrid configuration to achieve simultaneously a high magnetic field with a short period. The magnet is external to a … more

Date: March 1, 1983

Creator: Hoyer, E.; Chan, T.; Chin, J. W. G.; Halbach, K.; Kim, K. J.; Winick, H. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Storage-ring FEL for the vuv

A free-electron laser for the vuv operating in a storage ring requires an electron beam of high density and low energy spread and a short wavelength, narrow-gap undulator. These conditions tend to produce longitudinal and transverse beam instabilities, excessive beam growth through multiple intrabeam scattering, and a short gas-scattering lifetime. Passing the beam only occasionally through the undulator in a by-pass straight section, as proposed by Murphy and Pellegrini, allows operation in a … more

Date: September 1, 1984

Creator: Peterson, J. M.; Bisognano, J. J.; Garren, A. A.; Halbach, K.; Kim, K. J. & Sah, R. C.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

The evolution and limits of spectral bandwidth in free electron lasers

We study the bandwidths in free electron lasers (FELs) under different circumstances; for weakly saturated FELs in storage rings, the bandwidth is given be the formula derived in the super mode theory, while it is given by the Fourier transform of the electron pulse length in the strongly saturated FELs in linacs. The limiting bandwidth for the case of a DC beam is given by a Schawlow-Townes formula, but the approach to the limit is very slow. 14 refs.

Date: November 1, 1990

Creator: Kim, K. J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Crossed undulator system for a variable polarization synchrotron radiation source

A crossed undulator system can produce synchrotron radiation whose polarization is arbitrary and adjustable. The polarization can be linear and modulated between two mutually perpendicular directions, or it can be circular and can be modulated between right and left circular polarizations. The system works on low emittance electron storage rings and can cover a wide spectral range. Topics discussed include the basic principle of the system, the design equations and the limitations in performanc… more

Date: May 1, 1984

Creator: Kim, K. J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Achromatic and isochronous electron beam transport for tunable free electron lasers

We have continued the study of a suitable electron beam transport line, which is both isochronous and achromatic, for the free electron laser being designed at Lawrence Berkeley Laboratory. A refined version of the beam transport optics is discussed that accommodates two different modes of FEL wavelength tuning. For the fine tuning involving a small change of the electron beam energy, sextupoles are added to cancel the leading nonlinear dispersion. For the main tuning involving the change of th… more

Date: September 1, 1991

Creator: Bengtsson, J. & Kim, K. J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Slotted coax as a beam electrode

The slot coupled TEM line has been employed at CERN as a pick up electrode in the GHz range. It is a compact and broad band device, and will be quite attractive if the coupling efficiency is competitive with an array of quarter wave loops. In this paper, we study various properties of such a structure.

Date: March 1, 1983

Creator: Lambertson, G. R.; Kim, K. J. & Voelker, F. V.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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New formulation of synchrotron radiation optics using the Wigner distribution

It is shown that the Wigner distribution provides a proper framework in which the propagation and imaging characteristics of synchrotron radiation can be analyzed, taking fully into account the effect of diffraction and electron beam emittance. The Wigner distribution can be interpreted as a phase-space density of photon flux, i.e., the brightness, and transforms through a general optical medium in the same way as in the case of collection of geometric rays. The brightness due to a collection o… more

Date: November 1, 1985

Creator: Kim, K. J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Design overview of a highly stable infrared free electron laser at LBL

An infrared free electron laser (IRFEL) is being designed for the Chemical Dynamics Research Laboratory (CDRL) at LBL. The FEL is based on a 50 MeV RF linac operating in synchronization to the Advanced Light Source (ALS), and will produce intense (100 {mu}J per micropulse), narrow bandwidth (narrower than 0.1%) radiation between 3 {mu} and 50 {mu}. In the design, we pay particular attention to the FEL stability issues and require that the fluctuations in electron beam energy and in timing be le… more

Date: November 1, 1990

Creator: Kim, K. J.; Berz, M.; Chattopadhyay, S.; Gough, R.; Kim, C.; Kung, A. H. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department