First Name: K
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Last Name: Halbach
Full Name: K. Halbach
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12 papers
| title: | Research and development toward a 4.5-1.5 angstrom linac coherent light source (LCLS) at SLAC |
| format: | conference procceeding |
| conference: | 17th International Free Electron Laser Conference |
| year: | 1996 |
| 32 authors: | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
| abstract: | In recent years significant studies have been initiated on the feasibility of utilizing a portion of the 3 km S-band accelerator at SLAC to drive a short wavelength (4.5-1.5 Angstrom) Linac Coherent Light Source (LCLS), a Free-Electron Laser (FEL) operating in the Self-Amplified Spontaneous Emission (SASE) regime. Electron beam requirements for single-pass saturation in a minimal time include: 1) a peak current in the 7 kA range, 2) a relative energy spread of <0.05%, add 3) a transverse emittance, epsilon [rad-m], approximating the diffraction-limit condition epsilon=lambda/4 pi, where lambda[m] is the output wavelength. Requirements on the insertion device include field error levels of 0.02% for keeping the electron bunch centered on and in phase with the amplified photons, and a focusing beta of 8 m/rad for inhibiting the dilution of its transverse density. Although much progress has been made in developing individual components and beam-processing techniques necessary for LCLS operation down to similar to 20 Angstrom, a substantial amount of research and development is still required in a number of theoretical and experimental areas leading to the construction and operation of a 4.5-1.5 Angstrom LCLS. In this paper we report on a research and development program underway and in planning at SLAC for addressing critical questions in these areas. These include the construction and operation of a linac test stand for developing laser-driven photocathode rf guns with normalized emittances approaching 1 mm-mrad; development of advanced beam compression, stability, and emittance control techniques at multi-GeV energies; the construction and operation of a FEL Amplifier Test Experiment (FATE) for theoretical and experimental studies of SASE at IR wavelengths; an undulator development program to investigate superconducting, hybrid/permanent magnet (hybrid/PM), and pulsed-Cu technologies; theoretical and computational studies of high-gain FEL physics and LCLS component designs; development of X-ray optics and instrumentation for extracting, modulating, and delivering photons to experimental users; and the study and development of scientific experiments made possible by the source properties of the LCLS. |
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| title: | Short wavelength FELs using the SLAC linac |
| format: | journal article |
| year: | 1994 |
| 30 authors: | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
| abstract: | We have studied the use of the SLAC linac to drive FELs at wavelengths down to a few angstroms. Lasing would be achieved in a single pass of a low emittance, high peak current, high energy eelctron beam through a long undulator by Self-Amplified-Spontaneous-Emissin (SASE). About 10(13) photons per pulse can be produced in 100 fs pulses at a 120 Hz rate, corresponding to brightness levels of about 10(22) average and 10(32) peak. Peak power levels are tens of GW. Electron energies of 10-20 GeV are required. Signifcant imporvement of FEL performance seems possible using harmonic generation techniques according to results from numerical simulations. |
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| title: | Prospects for high power linac coherent light source (LCLS) development in the 1000 angstrom-1 angstrom wavelength range |
| format: | conference procceeding |
| conference: | 4th International Colloquium on X-Ray Lasers |
| year: | 1994 |
| 26 authors: | | | | | | | | | | | | | | | | | | | | | | | | | | |
| abstract: | Electron bunch requirements for single-pass saturation of a free-electron laser (FEL) operating at full transverse coherence in the self-amplified spontaneous emission (SASE) mode include: 1) a high peak current, 2) a sufficiently low relative energy spread, and 3) a transverse emittance epsilon (r-m) satisfying the condition epsilon <= lambda /4 pi , where lambda (m) is the output wavelength of the FEL. In the insertion device that induces the coherent amplification, the prepared electron bunch must be kept on a trajectory sufficiently collinear with the amplified photons without significant dilution of its transverse density. In this paper we discuss a Linac coherent light source (LCLS) based on a high energy accelerator such as, e.g., the 3 km S-band structure at the Stanford Linear Accelerator Center (SLAC), followed by a long high-precision undulator with superimposed quadrupole (FODO) focusing, to fulfill the given requirements for SASE operation in the 1000 angstrom-1 angstrom range. The electron source for the linac, an RF gun with a laser-excited photocathode featuring a normalized emittance in the 1-3 mm-mrad range, a longitudinal bunch duration of the order of 3 ps, and approximately 10(-9) C/bunch, is a primary determinant of the required low transverse and longitudinal emittances. Acceleration of the injected bunch to energies in the 5-25 GeV range is used to reduce the relative longitudinal energy spread in the bunch, as well as to reduce the transverse emittance to values consistent with the cited wavelength regime. Two longitudinal compression stages are employed to increase the peak bunch current to the 2-5 kA levels required for sufficiently rapid saturation. The output radiation is delivered, via a grazing-incidence mirror bank, to optical instrumentation and a multi-user beam line system. Technological requirements for LCLS operation at 40 angstroms, 4.5 angstroms, and 1.5 angstroms are examined. |
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| title: | The SLAC soft X-ray high power FEL |
| format: | conference procceeding |
| conference: | 15th International Free Electron Laser Conference |
| year: | 1994 |
| 23 authors: | | | | | | | | | | | | | | | | | | | | | | | |
| abstract: | We discuss the design and performance of a 2 to 4 nm FEL operating in self-amplified spontaneous emission (SASE), using a photoinjector to produce the electron beam, and the SLAC linac to accelerate it to an energy of about 7 GeV. Longitudinal bunch compression is used to increase the peak current to 2.5 kA, while reducing the bunch length to about 40 mu m. The FEL field gain length is about 6 m, and the saturation length is about 60 m. The saturated output power is about 10 GW, corresponding to about 10/sup 14/ photons in a single pulse in a bandwidth of about 0.1%, with a pulse duration of 0.16 ps. Length compression, emittance control, phase stability, FEL design criteria, and parameter tolerances are discussed. (15 References). |
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| title: | Design considerations for a 60 meter pure permanent magnet undulator for the SLAC Linac Coherent Light Source (LCLS) |
| format: | conference procceeding |
| conference: | 1993 Particle Accelerator Conference |
| year: | 1993 |
| 7 authors: | | | | | | | |
| abstract: | In this paper we describe design, fabrication, and measurement aspects of a pure permanent magnet (PM) insertion device designed to operate as an FEL at a 1st harmonic energy of 300 eV and an electron energy of 7 GeV in the self-amplified spontaneous emission regime. (13 References). |
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| title: | A 2-4 nm Linac Coherent Light Source (LCLS) using the SLAC linac |
| format: | conference procceeding |
| conference: | 1993 Particle Accelerator Conference |
| year: | 1993 |
| 20 authors: | | | | | | | | | | | | | | | | | | | | |
| abstract: | We describe the use of the SLAC linac to drive a unique, powerful, short wavelength Linac Coherent Light Source (LCLS). Operating as an FEL, lasing would be achieved in a single pass of a high peak current electron beam through a long undulator by self-amplified spontaneous emission. The main components are a high-brightness rf photocathode electron gun; pulse compressors; about 1/5 of the SLAC linac; and a long undulator with a FODO quadrupole focusing system. Using electrons below 8 GeV, the system would operate at wavelengths down to about 3 nm, producing [right angle bracket]or=10 GW of peak power in sub-ps pulses. At a 120 Hz rate the average power is approximately=1 W. (6 References). |
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| title: | A 2 to 4 nm high power FEL on the SLAC linac |
| format: | conference procceeding |
| conference: | 14th International Free Electron Laser Conference |
| year: | 1993 |
| 13 authors: | | | | | | | | | | | | | |
| abstract: | The authors report the results of preliminary studies of a 2 to 4 nm SASE FEL, using a photoinjector to produce the electron beam, and the SLAC linac to accelerate it to an energy up to 10 GeV. Longitudinal bunch compression is used to increase ten fold the peak current to 2.5 kA, while reducing the bunch length to the subpicosecond range. The saturated output power is in the multi-gigawatt range, producing about 10/sup 14/ coherent photons within a bandwidth of about 0.2% r.m.s., in a pulse of several millijoules. At 120 Hz repetition rate the average power is about 1 W. The system is optimized for X-ray microscopy in the water window around 2 to 4 nm, and will permit imaging a biological sample in a single subpicosecond pulse. (21 References). |
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| title: | A high luminosity superconducting mini collider for phi meson production and particle beam physics |
| format: | conference procceeding |
| conference: | 1991 Particle Accelerator Conference |
| year: | 1991 |
| 14 authors: | | | | | | | | | | | | | | |
| abstract: | A 510-MeV electron-positron collider has been proposed at the University of California at Los Angeles to study particle beam physics and phi-meson physics at luminosities larger than 1032 cm/sup -2/s/sup -1/. The collider consists of a single compact superconducting storage ring (SMC), with a bending field of 4 T and a current larger than 1 A. A discussion is presented of the main characteristics of this system and its major technical components: superconducting dipoles and the RF vacuum and injection systems. (6 References). |
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| title: | Feasibility study of a storage ring for a high-power XUV free-electron laser |
| format: | journal article |
| year: | 1986 |
| 12 authors: | | | | | | | | | | | | |
| abstract: | A high-gain free-electron lase (FEL), operating in a special by-pass of a storage ring, can provide tens of megawatts of coherent power at wavelengths shorter than 1000 AA. The requirements on beam quality are demanding-a few hundred amperes of peak current in an emittance of about 10/sup -8/ m-rad with a relative energy spread of about 10/sup -3/. Designing an electron storage ring with the required characteristics involves a comprehensive analysis of the restrictions arising from, and relationships between, the FEL physics, the multiparticle beam phenomena, and the ring lattice structure. A summary of such a study is reported and some design examples are given. (39 References). |
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| title: | Design concepts of a storage ring for a high power XUV free electron laser |
| format: | conference procceeding |
| conference: | 7th International Free Electron Laser Conference |
| year: | 1986 |
| 12 authors: | | | | | | | | | | | | |
| abstract: | The authors report on 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. They describe a method for the optimization of the design of the storage ring where several competing and often conflicting requirements come into play. They present an example design of a ring that satisfies the required conditions of beam quality and is able to produce coherent radiation at 400 AA with tens of megawatts of peak power. (11 References). |
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| title: | Optimization of the parameters of a storage ring for a high power XUV free electron laser |
| format: | conference procceeding |
| conference: | International Conference on Insertion Devices for Synchrotron Sources |
| year: | 1986 |
| 12 authors: | | | | | | | | | | | | |
| abstract: | The authors describe the operation of an XUV high gain FEL operating within a bypass of an electron storage ring, and discuss the implications on storage ring optimization imposed be FEL requirements. It transpires that, in the parameter regime of interest, collective effects within the beam play an important role. For example, intrabeam scattering dilutes the transverse emittance of the beam and the microwave instability increases the momentum spread. Both phenomena reduce the effectiveness of the FEL. A computer code, ZAP, has been written which, for a given lattice design, takes all such effects into consideration and produces a figure of merit for FEL operation for that machine. They show the results of ZAP for several storage ring designs, all optimized for FEL operation, and present a design example of a facility capable of producing coherent radiation at 400 AA with tens of megawatts of peak power. (24 References). |
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| title: | Storage ring design for a short wavelength FEL |
| format: | conference procceeding |
| conference: | 1985 Particle Accelerator Conference |
| year: | 1985 |
| 12 authors: | | | | | | | | | | | | |
| abstract: | A high gain free electron laser (FEL) operating in a special bypass of a storage ring can provide tens of megawatts of coherent power at wavelengths shorter than 1000 AA. The requirements on beam qualities are demanding, a few hundred amperes of peak current in an emittance of about 10/sup -8/ m-rad with a relative energy spread of approximately 10/sup -3/. Designing an electron storage ring with the required characteristics involves a comprehensive analysis of the restrictions from, and relationships between, the FEL physics, the multiparticle beam phenomena, and the ring lattice structure. A summary of such a study is reported and some design examples are given. (12 References). |
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