33 results on '"Zhirong Huang"'
Search Results
2. Study of a free-electron laser driven by a laser-plasma accelerated beam at Peking University
- Author
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Gang Zhao, Senlin Huang, Xueqing Yan, Zhirong Huang, Ronghao Hu, Ling Zeng, Weilun Qin, Haiyang Lu, Kexin Liu, and Yuantao Ding
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Physics ,Nuclear and High Energy Physics ,business.industry ,Free-electron laser ,Pulse duration ,Undulator ,Laser ,law.invention ,Transverse plane ,Optics ,Beamline ,law ,Physics::Accelerator Physics ,Thermal emittance ,business ,Instrumentation ,Beam (structure) - Abstract
The percent level energy spread and large divergence of laser-plasma beam are the main challenges of realizing compact short-wavelength free-electron lasers based on laser-plasma accelerators. These issues can be solved with proposed transverse gradient undulator method or bunch decompression method along with proper transport design. We present a study of using an expected 500 MeV laser-plasma beam with 0.3 m m ⋅ m r a d normalized emittance and 0.3 m r a d divergence at Peking University to drive compact free-electron laser at 30 nm. We employ the bunch decompression method with a chromatic matching beamline as well as the transverse gradient undulator method with assumed matched beam. Simulation shows that 700 MW power, 9.7 fs pulse duration and 0.85% relative bandwidth FEL output can be obtained using chromatic matched bunch decompression method. FEL with similar performance can be obtained using the transverse gradient undulator scheme.
- Published
- 2019
3. Control and application of beam microbunching in high brightness linac-driven free electron lasers
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Zhirong Huang and Gennady Stupakov
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Physics ,Nuclear and High Energy Physics ,Brightness ,010308 nuclear & particles physics ,Terahertz radiation ,business.industry ,Free-electron laser ,Radiation ,Laser ,01 natural sciences ,Instability ,Linear particle accelerator ,law.invention ,Optics ,law ,0103 physical sciences ,Physics::Accelerator Physics ,010306 general physics ,business ,Instrumentation ,Beam (structure) - Abstract
We review physical mechanisms and driving forces behind the microbunching instability in modern free-electron lasers . Laser heater and alternative methods to fight the instability are presented and evaluated. Advanced uses of the laser heater setup for temporal and spectral controls of the FEL and for intense THz production are discussed. A recent idea of using the microbunching instability for coherent generation of UV radiation is described. Noise suppression in relativistic beams is briefly reviewed.
- Published
- 2018
4. Effect of Annealing Temperature on Microstructure, Mechanical and Corrosion Resistance Properties of TA10 Titanium Alloy
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Han Xiao, Jiaxin Yu, Zhirong Huang, Hongyu Zhang, Haiguang Huang, Kun Yu, and Rongfeng Zhou
- Published
- 2021
5. Photon beamlines and diagnostics at LCLS
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J. Galayda, Joshua J. Turner, Y. Feng, D. McMahon, Henrik Loos, C. Gardener, T. McCarville, Daniel Ratner, K. Kishiyama, David H. Dowell, J. Welch, J. Rzepiela, Ryan Coffee, Jeff C. Robinson, Heinz-Dieter Nuhn, Zhirong Huang, R. M. Bionta, A. Miahnahri, Alan Fisher, Regina Soufli, D. Ryutov, S. Lewis, Mark A. McKernan, Stefan Moeller, K. Fong, F.-J. Decker, Stefan P. Hau-Riege, Axel Brachmann, E. Ables, Jacek Krzywinski, P. Hering, Gerald Yocky, J. Arthur, R. H. Iverson, Linda L. Ott, S. Shen, H. Tompkins, Stephan Friedrich, Marc Messerschmidt, P. Stefan, Sasha Gilevich, J. Frisch, B. White, M. J. Pivovaroff, Yuantao Ding, D. Schultz, Baxter Abraham, Juhao Wu, Jerome B. Hastings, S. A. Edstrom, T. Smith, Paul Emma, G. Hays, and G. Pile
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Physics ,Nuclear and High Energy Physics ,Photon ,Optics ,law ,business.industry ,Free-electron laser ,Electrical engineering ,Particle accelerator ,business ,Instrumentation ,Linear particle accelerator ,law.invention - Abstract
The LCLS hard X-ray Free Electron Laser at SLAC reported first lasing in April 2009. Since then two successful user runs have been completed at the two soft X-ray stations. The first hard X-ray station has started commissioning in July 2010. Beam diagnostics play an essential role for tuning the machine and delivering the requested beam properties to the users. An overview of the LCLS photon diagnostics will be presented including some selected commissioning results. Plans for future improvements and upgrades will be briefly discussed.
- Published
- 2011
6. Crossed undulator polarization control for X-ray FELs in the saturation regime
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H. Geng, Yuantao Ding, and Zhirong Huang
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Physics ,Nuclear and High Energy Physics ,business.industry ,X-ray ,Self-amplified spontaneous emission ,Undulator ,Polarization (waves) ,Wavelength ,Optics ,Physics::Accelerator Physics ,Degree of polarization ,Statistical analysis ,business ,Instrumentation ,Saturation (magnetic) - Abstract
The crossed-planar undulator is a promising scheme for full and rapid control of X-ray polarization in a high-gain FEL. In this paper, we study the effectiveness of a crossed undulator for SASE FELs in the saturation regime in order to achieve stable operation. Statistical analysis is performed to show that the degree of polarization remains high in the saturation regime, and controllable polarization at the third harmonic of the FEL wavelength is obtained by adjusting the strength of the vertical undulator. We also propose a modified scheme for polarization control using a short pair of crossed undulators tuned to the second harmonic of the main undulator. The scheme is straightforward to implement and can reach high degree of polarization with high stability.
- Published
- 2010
7. Free electron lasers: Present status and future challenges
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Gennady Stupakov, Dinh C. Nguyen, George R. Neil, Paul Emma, Fernando Sannibale, J.N. Corlett, James B. Murphy, Robert Rimmer, R.P. Walker, Alexander Zholents, Kwang-Je Kim, Zhirong Huang, R. Lindberg, Claudio Pellegrini, William A. Barletta, and Joseph Bisognano
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Physics ,Nuclear and High Energy Physics ,Brightness ,Photon ,business.industry ,Free-electron laser ,Particle accelerator ,Laser ,Linear particle accelerator ,law.invention ,Upgrade ,Optics ,law ,business ,Instrumentation ,Coherence (physics) - Abstract
With the scientific successes of the soft X-ray FLASH facility in Germany and the recent spectacular commissioning of the Linac Coherent Light Source at SLAC, free electron lasers are poised to take center stage as the premier source of tunable, intense, coherent photons of either ultra-short time resolution or ultra-fine spectral resolution, from the far infrared to the hard X-ray regime. This paper examines the state of the art in FEL performance and the underlying enabling technologies. It evaluates the state of readiness of the three basic machine architectures—SASE FELs, seeded FELs, and FEL oscillators—for the major X-ray science user facilities on the 5–10 years time scale and examines the challenges that lie ahead for FELs to achieve their full potential throughout the entire spectral range. In soft and hard X-rays, high longitudinal coherence, in addition to full transverse coherence, will be the key performance upgrade; ideas using laser-based or self-seeding or oscillators can be expected to be qualitatively superior to today's SASE sources. Short pulses, from femtoseconds to attoseconds, can be realistically envisioned. With high repetition rate electron sources coupled to superconducting radiofrequency linear accelerators, unprecedented average beam brightness will be possible and many users would be served simultaneously by a single accelerator complex.
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- 2010
8. Analysis of slice transverse emittance evolution in a photocathode RF gun
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Zhirong Huang, Ji Qiang, and Yuantao Ding
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Physics ,Nuclear and High Energy Physics ,business.industry ,Particle accelerator ,Space charge ,Photocathode ,law.invention ,Transverse plane ,Optics ,law ,Cathode ray ,Physics::Accelerator Physics ,Thermal emittance ,Beam emittance ,business ,Instrumentation ,Electron gun - Abstract
The slice transverse emittance of an electron beam is of critical significance for an x-ray FEL. In a photocathode RF gun, the slice transverse emittance is not only determined by the emission process, but also influenced strongly by the non-linear space charge effect. In this paper, we study the slice transverse emittance evolution in a photocathode RF gun using a simple model that includes effects of RF acceleration, focusing, and space charge force. The results are compared with IMPACT-T space charge simulations and may be used to understand the development of the slice emittance in an RF gun.
- Published
- 2008
9. Steady-state analysis of short-wavelength, high-gain FELs in a large storage ring
- Author
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Alex Chao, R. Hettel, Yunhai Cai, Zhirong Huang, Karl Bane, and Claudio Pellegrini
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Physics ,Nuclear and High Energy Physics ,Brightness ,business.industry ,Extreme ultraviolet lithography ,Particle accelerator ,Radiation ,law.invention ,Power (physics) ,Wavelength ,Optics ,Orders of magnitude (time) ,law ,Physics::Accelerator Physics ,business ,Instrumentation ,Storage ring - Abstract
Storage ring FELs have operated successfully in the low-gain regime using optical cavities. Discussions of a high-gain FEL in a storage ring typically involve a special bypass to decouple the FEL interaction from the storage ring dynamics. In this paper, we investigate the coupled dynamics of a high-gain FEL in a large storage ring such as PEP and analyze the equilibrium solution. We show that an FEL in the EUV and soft x-ray regimes can be integrated into a very bright storage ring and potentially provides three orders of magnitude improvement in the average brightness at these radiation wavelengths. We also discuss possibilities of seeding with HHG sources to obtain ultra-short, high-peak power EUV and soft x-ray pulses.
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- 2008
10. Experiments with electron beam modulation at the DUVFEL accelerator
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William Graves, Brian Sheehy, L. Carr, Timur Shaftan, C. Limborg, Henrik Loos, Z. Wu, James Rose, Li-Hua Yu, A. Doyuran, and Zhirong Huang
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Physics ,Nuclear and High Energy Physics ,Beam diameter ,Free-electron laser ,Particle accelerator ,Electron ,Space charge ,law.invention ,law ,Modulation ,Phase space ,Cathode ray ,Physics::Accelerator Physics ,Atomic physics ,Instrumentation - Abstract
Recently strong modulation of the electron bunch longitudinal phase space was obtained in the DUVFEL accelerator at NSLS. The chirped beam energy spectra exhibit a spiky structure with a subpicosecond spike separation. A model based on the longitudinal space-charge effect has been suggested as an explanation of the observed effect. For characterization of the structure and comparison with the model we performed several experiments. In this paper we present experimental data and discuss them in relation to the model.
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- 2004
11. Femtosecond X-ray pulses from a frequency-chirped SASE FEL
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Zhirong Huang and Samuel Krinsky
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Physics ,Nuclear and High Energy Physics ,business.industry ,Pulse duration ,Particle accelerator ,Undulator ,Radiation ,Linear particle accelerator ,law.invention ,Optics ,law ,Femtosecond ,Physics::Atomic and Molecular Clusters ,Physics::Accelerator Physics ,Optoelectronics ,Spontaneous emission ,business ,Instrumentation ,Monochromator - Abstract
We discuss the temporal and spectral properties of self-amplified spontaneous emission (SASE) utilizing an energy-chirped electron beam. A short temporal pulse is generated by using a monochromator to select a narrow radiation bandwidth from the frequency-chirped SASE. For the filtered radiation, the minimum pulse length is limited by the intrinsic SASE bandwidth, while the number of modes and the energy fluctuation can be controlled through the monochromator bandwidth. Two cases are considered: (1) placing the monochromator at the end of a single long undulator; (2) placing the monochromator after an initial undulator and amplifying the short-duration output in a second undulator. We analyze these cases and show that tens of femtosecond X-ray pulses may be generated for the linac coherent light source.
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- 2004
12. Femtosecond X-ray pulses from a spatially chirped electron bunch in a SASE FEL
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P. Emma and Zhirong Huang
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Physics ,Nuclear and High Energy Physics ,business.industry ,Pulse duration ,Electron ,Radiation ,Undulator ,Linear particle accelerator ,Optics ,Femtosecond ,Chirp ,Cathode ray ,Physics::Accelerator Physics ,business ,Instrumentation - Abstract
We propose a simple method to produce short x-ray pulses using a spatially chirped electron bunch in a SASE FEL. The spatial chirp is generated using an rf deflector which produces a transverse offset (in y and/or y') correlated with the longitudinal bunch position. Since the FEL gain is very sensitive to an initial offset in the transverse phase space at the entrance of the undulator, only a small portion of the electron bunch with relatively small transverse offset will interact significantly with the radiation, resulting in an x-ray pulse length much shorter than the electron bunch length. The x-ray pulse is also naturally phase locked to the rf deflector and so allows high precision timing synchronization. We discuss the generation and transport of such a spatially chirped electron beam and show that tens of femtosecond long pulse can be generated for the linac coherent light source (LCLS).
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- 2004
13. Impact of beam energy modulation on rf zero-phasing microbunch measurements
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Timur Shaftan and Zhirong Huang
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Physics ,Nuclear and High Energy Physics ,business.industry ,Particle accelerator ,Phaser ,Space charge ,law.invention ,Amplitude ,Optics ,law ,Modulation ,Cathode ray ,Physics::Accelerator Physics ,business ,Instrumentation ,Beam energy ,Beam (structure) - Abstract
Temporal profile of a simple bunch distribution may be obtained by measuring the horizontal density profile of an energy-chirped electron beam at a dispersive region using the rf zero-phasing technique. For an energy-modulated beam, the horizontal profile obtained by this technique is also modulated with an enhanced amplitude. We study the microbunching experiment at the NSLS source development laboratory and show that the horizontal modulation observed by the rf zero-phasing technique can be explained by the space–charge-induced energy modulation in the accelerator.
- Published
- 2004
14. Spontaneous and amplified radiation at the initial stage of a SASE FEL
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Zhirong Huang and Kwang-Je Kim
- Subjects
Physics ,Nuclear and High Energy Physics ,business.industry ,Free-electron laser ,Self-amplified spontaneous emission ,Particle accelerator ,Radiation ,Undulator ,Laser ,Wave equation ,law.invention ,Optics ,law ,Physics::Accelerator Physics ,Spontaneous emission ,business ,Instrumentation - Abstract
At the initial stage of a self-amplified spontaneous emission (SASE) free-electron laser (FEL), spontaneous undulator radiation in certain experimental configurations can dominate the amplified signal over an extended undulator distance. In this paper they study both the spontaneous and the amplified radiation in the framework of the paraxial wave equation and determine the transition from the dominance of spontaneous emission to exponential amplification. They compare theoretical expectations with SASE simulation codes GINGER and GENESIS.
- Published
- 2003
15. Observations of z-dependent microbunching harmonic intensities using COTR in a SASE FEL
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Yuelin Li, Bingxin Yang, John W. Lewellen, Stephen V. Milton, Kwang-Je Kim, William Berg, Vadim Sajaev, Alex H. Lumpkin, M. Erdmann, Sandra Biedron, Zhirong Huang, Roger J. Dejus, Michael Borland, Elizabeth Moog, and Yong-Chul Chae
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Physics ,Nuclear and High Energy Physics ,business.industry ,Undulator ,Laser ,law.invention ,Optics ,Transition radiation ,law ,Harmonics ,Harmonic ,Cathode ray ,Physics::Accelerator Physics ,High harmonic generation ,Spontaneous emission ,business ,Instrumentation - Abstract
The nonlinear generation of harmonics in a self-amplified spontaneous emission (SASE) free-electron laser (FEL) continues to be of interest. Complementary to such studies is the search for information on the electron beam microbunching harmonic components, which are revealed by coherent optical transition radiation (COTR) experiments. An initial z-dependent set of data has been obtained with the fundamental at 530 nm and the second harmonic at 265 nm. The latter data were collected after every other undulator in a nine-undulator string. These results are compared to estimates based on GINGER and an analytical model for nonlinear harmonic generation.
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- 2003
16. Theory and simulation of CSR microbunching in bunch compressors
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P. Emma, Zhirong Huang, Kwang-Je Kim, and Michael Borland
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Physics ,Nuclear and High Energy Physics ,Series (mathematics) ,business.industry ,Particle accelerator ,Mechanics ,Bending ,Instability ,Integral equation ,Linear particle accelerator ,law.invention ,Optics ,law ,Modulation ,Physics::Accelerator Physics ,business ,Instrumentation ,Gas compressor - Abstract
CSR microbunching instability in bunch compressors is studied both analytically and numerically. The iterative solutions of the integral equation for the instability provide approximate expressions of CSR microbunching due to initial density and energy modulation, and can be applied to a series of bending systems consisting of multiple compressor chicanes and transport lines. Two similar but independent simulation methods are developed and are compared to each other as well as with theory. We determine the total gain in density modulation for all bend systems of the Linac Coherent Light Source and discuss initial conditions that start the unstable process.
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- 2003
17. Evidence for transverse dependencies in COTR and microbunching in a SASE FEL
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Vadim Sajaev, Kwang-Je Kim, William Berg, Roger J. Dejus, Elizabeth Moog, John W. Lewellen, Sandra Biedron, Zhirong Huang, M. Erdmann, D.W Rule, Yong-Chul Chae, Stephen V. Milton, Yuelin Li, Bingxin Yang, Alex H. Lumpkin, and Michael Borland
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Physics ,Nuclear and High Energy Physics ,business.industry ,Particle accelerator ,Radiation ,Laser ,Electromagnetic radiation ,law.invention ,Transverse plane ,Optics ,Transition radiation ,law ,Cathode ray ,Physics::Accelerator Physics ,Spontaneous emission ,Atomic physics ,business ,Instrumentation - Abstract
Using coherent optical transition radiation (COTR) techniques, we have observed transverse dependencies, which in some aspects relate to the electron beam microbunching in a visible wavelength (540 nm) self-amplified spontaneous emission (SASE) free-electron laser (FEL). The experimental COTR observations include the z-dependent e-beam sizes, the z-dependent angular distributions, and the z-dependent spectra (which show an x-dependence). A 30-40% narrowing of the observed beam size using COTR is explainable by the mechanism's dependence on the square of the number of microbunched particles. However, additional effects are needed to explain beam size reductions by factors of 2-3 at different z locations. Localized e-beam structure in the gun or induced in the bunch compression process may result in microbunching transverse dependence, and hence the observed COTR effects.
- Published
- 2003
18. Time-resolved measurement of a self-amplified free-electron laser
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Yuelin Li, John W. Lewellen, Stephen V. Milton, Zhirong Huang, and Vadim Sajaev
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Physics ,Nuclear and High Energy Physics ,business.industry ,Resolution (electron density) ,Free-electron laser ,Self-amplified spontaneous emission ,Physics::Optics ,Electron ,Laser ,law.invention ,Optics ,law ,Chirp ,Physics::Accelerator Physics ,Spontaneous emission ,Physics::Atomic Physics ,business ,Instrumentation ,Energy (signal processing) - Abstract
We report on a time-resolved measurement of self-amplified spontaneous emission free-electron laser (FEL) pulses. We observed that the spikes in such FEL pulses have an intrinsic positive chirp and the energy chirp in the electron bunch mapped directly into the FEL output. The measurement also provides rich information on the statistics of the FEL pulses.
- Published
- 2003
19. Spectral measurements of the second harmonic of the SASE FEL radiation at APS
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Vadim Sajaev and Zhirong Huang
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Physics ,Nuclear and High Energy Physics ,business.industry ,Spectral properties ,Free-electron laser ,Self-amplified spontaneous emission ,Particle accelerator ,Advanced Photon Source ,Radiation ,law.invention ,Wavelength ,Optics ,law ,Harmonics ,Physics::Accelerator Physics ,business ,Instrumentation - Abstract
We present the z-dependent spectral measurement results for the second harmonic of the SASE FEL radiation before and after saturation. The measurements were performed at the Advanced Photon Source FEL with the fundamental wavelength of 530 nm. The spectral properties of the second harmonic are compared with those of the fundamental and with the theoretical expectations.
- Published
- 2003
20. Z-dependent spectral measurements of SASE FEL radiation at APS
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Efim Gluskin, P.K. Den Hartog, Yuelin Li, Stephen V. Milton, Sandra Biedron, Zhirong Huang, John W. Lewellen, Kwang-Je Kim, Oleg Makarov, Vadim Sajaev, and Elizabeth Moog
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Physics ,Nuclear and High Energy Physics ,business.industry ,Electromagnetic spectrum ,Self-amplified spontaneous emission ,Free-electron laser ,Particle accelerator ,Advanced Photon Source ,Radiation ,Laser ,law.invention ,Optics ,law ,Physics::Accelerator Physics ,Spontaneous emission ,Atomic physics ,business ,Instrumentation - Abstract
We report on the first measurements of the dependence on the axial distance z of the spectrum of self-amplified spontaneous emission free-electron laser (SASE FEL) radiation. The measurements are performed under different FEL conditions in the wavelength range from 265 to 530 nm. Spectral measurements of the radiation at FEL saturation are included. The z-dependence of the radiation spectrum is compared with theory and simulations.
- Published
- 2003
21. The sensitivity of nonlinear harmonic generation to electron beam quality in free electron lasers
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William M. Fawley, P.L. Ottaviani, Alberto Renieri, Kwang-Je Kim, Stephen V. Milton, Heinz-Dieter Nuhn, Sandra Biedron, Zhirong Huang, G. Dattoli, and Henry P. Freund
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Physics ,Nuclear and High Energy Physics ,business.industry ,Undulator ,Quality (physics) ,Optics ,Harmonics ,Harmonic ,Physics::Accelerator Physics ,High harmonic generation ,Harmonic number ,Thermal emittance ,Sensitivity (control systems) ,business ,Instrumentation - Abstract
The generation of harmonics through a nonlinear mechanism driven by bunching at the fundamental has sparked interest as a path toward enhancing and extending the usefulness of an x-ray free-electron laser (FEL) facility. The sensitivity of the nonlinear harmonic generation to undulator imperfections, electron beam energy spread, peak current, and emittance is important in an evaluation of the process. Typically, linear instabilities in FELs are characterized by increased sensitivity to both electron beam and undulator quality with increasing harmonic number. However, since the nonlinear harmonic generation mechanism is driven by the growth of the fundamental, the sensitivity of the nonlinear harmonic mechanism is not expected to be significantly greater than that of the fundamental. In this paper, they study the effects of electron beam quality, more specifically, emittance, energy spread, and peak current, on the nonlinear harmonics in a 1.5-{angstrom} FEL, and show that the decline in the harmonic emission roughly follows that of the fundamental.
- Published
- 2002
22. Present status and recent results from the APS SASE FEL
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Nikolay Vinokurov, Efim Gluskin, Roger J. Dejus, Michael Borland, Alex H. Lumpkin, M. Erdmann, John W. Lewellen, Sandra Biedron, Zhirong Huang, Yuelin Li, G. Wiemerslage, Bingxin Yang, Elizabeth Moog, M. W. Hahne, Emil Trakhtenberg, Isaac Vasserman, P.K. Den Hartog, Y. I. Eidelman, Brian Tieman, Kwang-Je Kim, William Berg, Stephen V. Milton, R. Soliday, Oleg Makarov, Vadim Sajaev, Yong-Chul Chae, C. Benson, B. Deriy, N. D. Arnold, and Alireza Nassiri
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Physics ,Nuclear and High Energy Physics ,Particle accelerator ,Advanced Photon Source ,Undulator ,Technology assessment ,law.invention ,Test line ,Identification (information) ,Light source ,law ,Electronic engineering ,National laboratory ,Instrumentation - Abstract
The Low-Energy Undulator Test Line (LEUTL) at the Advanced Photon Source, Argonne National Laboratory, is intended to demonstrate the basic operation of a SASE-based free-electron laser. Goals include comparison of experimental results With theoretical predictions and scaling laws, identification of problems relevant to fourth-generation light source construction and operation and the means of addressing them, the development of operational and diagnostic techniques to optimize SASE FEL performance and increase repeatability from run to run. and performance of initial pioneering experiments capable of exploiting the unique properties of the laser. The basic layout and operational philosophy of the LEUTL experiment is presented. A summary of past results, including saturation, is reviewed, and a description of recent results is presented. We conclude with future plans, which include pressing to shorter wavelengths and incorporating user experiments into the LEUTL experimental program. (Less)
- Published
- 2002
23. First observations of electron-beam microbunching in the deep ultraviolet at 265nm using COTR in a SASE FEL
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Sandra Biedron, Zhirong Huang, Yuelin Li, Bingxin Yang, Alex H. Lumpkin, Roger J. Dejus, Michael Borland, Vadim Sajaev, Elizabeth Moog, Stephen V. Milton, John W. Lewellen, M. Erdmann, and William Berg
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Physics ,Nuclear and High Energy Physics ,Spectrometer ,business.industry ,Imaging spectrometer ,Advanced Photon Source ,Particle accelerator ,Undulator ,Laser ,law.invention ,Lens (optics) ,Optics ,law ,Physics::Accelerator Physics ,Spontaneous emission ,business ,Instrumentation - Abstract
We have recently extended our microbunching experiments in a self-amplified spontaneous emission free-electron laser using coherent optical transition radiation (COTR) to the deep ultraviolet wavelengths (265 nm) for the first time. These experiments were performed as a complement to the Advanced Photon Source SASE FEL project's thrust to shorter wavelengths. In order to do this, the optical diagnostics have been modified to include UV-sensitive cameras, and an optical transport has been installed that involves sets of mirrors and UV–visible lens pairs after each undulator. These optics provide transport to the in-tunnel Oriel UV–visible spectrometer. Since this is an imaging spectrometer, both spectral and x/y-plane spatial information are simultaneously available by performing the projections of the images on the x- and y-axis. The initial angular distribution data and beam size data have been obtained in a z-dependent manner by sampling after every other undulator, or every 4.8 m at four z locations. Experiments with sampling of the COTR angular distribution and spectra after each of eight undulators are planned.
- Published
- 2002
24. Transverse and temporal characteristics of a high-gain free-electron laser in the saturation regime
- Author
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Zhirong Huang and Kwang-Je Kim
- Subjects
Physics ,Nuclear and High Energy Physics ,Sideband ,business.industry ,Free-electron laser ,Physics::Optics ,Electron ,Radiation ,Laser ,law.invention ,Computational physics ,Transverse plane ,Modulational instability ,Optics ,law ,Physics::Accelerator Physics ,Radiation mode ,business ,Instrumentation - Abstract
The transverse and the temporal characteristics of a high-gain free-electron laser are governed by refractive guiding and sideband instability, respectively. Using the self-consistent Vlasov–Maxwell equations, we explicitly determine the effective index of refraction and the guided radiation mode for an electron beam with arbitrary transverse size. Electrons trapped by the guided radiation execute synchrotron oscillation and hence are susceptible to the sideband instability. We explain the spectral evolution and determine the sideband growth rate. These theoretical predictions agree well with GINGER simulation results.
- Published
- 2002
25. Comprehensive z-dependent measurements of electron-beam microbunching using COTR in a saturated SASE FEL
- Author
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D.W Rule, Elizabeth Moog, John W. Lewellen, Vadim Sajaev, Yong-Chul Chae, Stephen V. Milton, Roger J. Dejus, Michael Borland, Yuelin Li, Bingxin Yang, Sandra Biedron, Zhirong Huang, Alex H. Lumpkin, M. Erdmann, Kwang-Je Kim, and William Berg
- Subjects
Physics ,Nuclear and High Energy Physics ,business.industry ,Particle accelerator ,Undulator ,Radiation ,Laser ,Photocathode ,Linear particle accelerator ,law.invention ,Optics ,law ,Cathode ray ,Physics::Accelerator Physics ,Spontaneous emission ,Atomic physics ,business ,Instrumentation - Abstract
We report the initial, comprehensive set of z-dependent measurements of electron-beam microbunching using coherent optical transition radiation (COTR) in a saturated self-amplified spontaneous emission (SASE) free-electron laser (FEL) experiment. In this case the FEL was operated near 530 nm using an enhanced facility including a bunch-compressed photocathode gun electron beam, linac, and 21.6 m of undulator length. The longitudinal microbunching was tracked by inserting a metal foil and mirror after each of the nine 2.4-m-long undulators and measuring the visible COTR spectra, intensity, angular, distribution, and spot size. We observed for the first time the z-dependent transition of the COTR spectra from simple lines to complex structure/sidebands near saturation. We also observed the change in the microbunching fraction after saturation, multiple fringes in the COTR interferogram that are consistent with involvement of a smaller core of the e-beam transverse distribution, and the second harmonic content of the microbunching. The results will be compared to relevant calculations using GENESIS and/or GINGER.
- Published
- 2002
26. Measurements of nonlinear harmonic generation at the Advanced Photon Source's SASE FEL
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John W. Lewellen, Kwang-Je Kim, William M. Fawley, William Berg, Elizabeth Moog, Michael Borland, Vadim Sajaev, P.K. Den Hartog, G. Wiemerslage, Efim Gluskin, Stephen V. Milton, M. Erdmann, Roger J. Dejus, Alex H. Lumpkin, Sandra Biedron, Zhirong Huang, Yuelin Li, Bingxin Yang, Henry P. Freund, and Alireza Nassiri
- Subjects
Physics ,Nuclear and High Energy Physics ,Photon ,business.industry ,Particle accelerator ,Advanced Photon Source ,Radiation ,Undulator ,law.invention ,Optics ,law ,Harmonics ,Cathode ray ,Physics::Accelerator Physics ,High harmonic generation ,business ,Instrumentation - Abstract
SASE saturation was recently achieved at the Advanced Photon Source's SASE FEL in the low-energy undulator test line (LEUTL) at 530 nm and 385 nm. The electron beam microbunching becomes more and more prominent until saturation is achieved. This bunching causes nonlinear harmonic emission that extends the usefulness of a SASE system in achieving shorter FEL wavelengths for the same electron beam energy. They have investigated the intensity of the fundamental and second-harmonic undulator radiation as a function of distance along the undulator line and present the experimental results and compare them to numerical simulations. In addition, they have measured the single-shot second harmonic spectra as well as the simultaneous fundamental and second harmonic spectra and present the experimental results.
- Published
- 2002
27. Nonlinear harmonic generation of coherent amplification and self-amplified spontaneous emission
- Author
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Kwang-Je Kim and Zhirong Huang
- Subjects
Physics ,Nuclear and High Energy Physics ,business.industry ,Self-amplified spontaneous emission ,Radiation ,Undulator ,Power (physics) ,Nonlinear system ,Planar ,Optics ,Quantum electrodynamics ,Harmonic ,Physics::Accelerator Physics ,High harmonic generation ,business ,Instrumentation - Abstract
Nonlinear harmonic generation in a uniform planar undulator is analyzed using the three-dimensional Maxwell–Klimontovich equations that include both even and odd harmonic emissions. After a certain stage of exponential growth, the dominant nonlinear harmonic interaction is caused by strong bunching at the fundamental. As a result, gain length, transverse profile, and temporal structure of these harmonic radiations are eventually determined by those of the fundamental. Transversely coherent third-harmonic radiation power is found to approach one percent of the fundamental power level for current high-gain FEL projects, while the power of the second-harmonic radiation is less but still significant for relatively low-energy FEL experiments.
- Published
- 2001
28. Solution to the initial value problem for a high-gain FEL via Van Kampen's method
- Author
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Zhirong Huang and Kwang-Je Kim
- Subjects
Physics ,Nuclear and High Energy Physics ,Normal mode ,Quantum electrodynamics ,Self-amplified spontaneous emission ,Initial value problem ,Thermal emittance ,Spontaneous emission ,Undulator ,Atomic physics ,Instrumentation ,Noise (radio) ,Coupling coefficient of resonators - Abstract
Using Van Kampen's normal mode expansion, we solve the initial value problem for a high-gain free-electron laser described by the three-dimensional Maxwell–Klimontovich equations. An expression of the radiation spectrum is given for the process of coherent amplification and self-amplified spontaneous emission. It is noted that the input coupling coefficient for either process increases with the initial beam energy spread. The effective start-up noise is identified as the coherent fraction of the spontaneous undulator radiation in one field gain length, and is larger with increasing energy spread and emittance mainly because of the increase in gain length.
- Published
- 2001
29. Quasilinear theory of high-gain FEL saturation
- Author
-
Nikolay Vinokurov, Zhirong Huang, Kwang-Je Kim, and O. A. Shevchenko
- Subjects
Physics ,Nuclear and High Energy Physics ,High-gain antenna ,Physics::Plasma Physics ,law ,Radiation field ,Quantum electrodynamics ,Quantum mechanics ,Free-electron laser ,Laser ,Instrumentation ,Saturation (magnetic) ,law.invention - Abstract
Understanding of saturation behavior is important to assess the performance of a high-gain free-electron laser. In this paper, we study the saturation mechanism using a quasilinear approximation to the coupled Maxwell–Vlasov equations. It is found that the quasilinear theory correctly describes the evolution of the radiation field from the small signal regime to reaching saturation.
- Published
- 2001
30. Observation and analysis of self-amplified spontaneous emission at the APS low-energy undulator test line
- Author
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Yuelin Li, Bingxin Yang, Efim Gluskin, W.G. Jansma, R.T. Keane, S. Xu, L. Morrison, B. Stejskal, D. Donkers, D. Meyer, D. Reigle, J. Attig, E.S. Lessner, F. Lenkszus, Kwang-Je Kim, J. Budz, William Berg, R.B. Zabel, W.R. Brzowski, R. Bechtold, G. Pile, John Power, K. Beczek, C. Benson, R. Ferry, G. Banks, T. Powers, M. Jaski, J. A. Biggs, R. Flood, S.J. Jones, K. Knoerzer, John Galayda, G.M. Markovich, C. Clark, J.H. Klick, R. Soliday, G.A. Sprau, G. Wiemerslage, V. Svirtun, Gil Travish, M. Erdmann, R.L. Gilmore, R.J. Dortwegt, J.C. Scapino, R. Hogrefe, R.A. Seglem, S. Labuda, K. Schroeder, J. Jagger, C.L. Doose, M. Knott, D. Ronzhin, Vadim Sajaev, Dean Walters, J.A. Torres, N.D. Arnold, M. W. Hahne, H. DeLeon, M. McDowell, J. Hoyt, S. Hanuska, Sang-Hoon Kim, J.R. Noonan, S. Christensen, T. Meier, Katherine Harkay, W. Michalek, A.L. Kelly, Michael Borland, A.J. Puttkammer, S. Berg, A. E. Grelick, J. Error, S.J. Pasky, D.L. Weyer, K. Boerste, Brian Tieman, Oleg Makarov, B. Deriy, W.P. McDowell, Alireza Nassiri, E. Theres, M. Bosek, J. Goetzen, S.J. Stein, Henry P. Freund, E. A. Crosbie, P. Castro, G.F. Trento, R. Gerig, W. Yoder, Sandra Biedron, Zhirong Huang, Emil Trakhtenberg, Yong-Chul Chae, J.M. Penicka, C. Gold, M.E. Conde, J.F. Sidarous, Robert Laird, E.R. Rotela, J.A. Carwardine, C.C. Putnam, Xuelong Wang, S. Sarkar, P.E. McNamara, G.A. Edwards, O. Singh, D. Wyncott, J. Warren, Y. I. Eidelman, J. Forrestal, R. Wright, T.L. Smith, A.J. Gorski, L. Reigle, R. Otto, C. Keyser, H. Friedsam, Wei Gai, L.C. Teng, Nicholas Sereno, A.F. Pietryla, Roger J. Dejus, G.A. Goeppner, K. Wilhelmi, M. Kirshenbaum, John W. Lewellen, Nikolay Vinokurov, S. Wesling, R.M. Lill, P.K. Den Hartog, K. Thompson, Sushil K. Sharma, P. Dombrowski, Alex H. Lumpkin, J. Pace, G. Harris, H. Moe, Stephen V. Milton, Ju Wang, Elizabeth Moog, Isaac Vasserman, A.L. Hillman, E.F. Russell, J. Gagliano, C. Pitts, J. Lang, R.J. Koldenhoven, J. Vacca, Glenn Decker, and D. Dohan
- Subjects
Physics ,Nuclear and High Energy Physics ,business.industry ,Self-amplified spontaneous emission ,Free-electron laser ,Advanced Photon Source ,Undulator ,Laser ,law.invention ,Optics ,law ,Magnet ,Cathode ray ,Spontaneous emission ,Atomic physics ,business ,Instrumentation - Abstract
Exponential growth of self-amplified spontaneous emission at 530 nm was first experimentally observed at the Advanced Photon Source low-energy undulator test line in December 1999. Since then, further detailed measurements and analysis of the results have been made. Here, we present the measurements and compare these with calculations based on measured electron beam properties and theoretical expectations.
- Published
- 2001
31. Effects of bunch density gradient in high-gain free-electron lasers
- Author
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Kwang-Je Kim and Zhirong Huang
- Subjects
Physics ,Free electron model ,Nuclear and High Energy Physics ,Amplified spontaneous emission ,Self-amplified spontaneous emission ,Particle accelerator ,Laser ,Computational physics ,law.invention ,Nonlinear system ,law ,Physics::Accelerator Physics ,Spontaneous emission ,Stimulated emission ,Atomic physics ,Instrumentation - Abstract
The authors investigate effects of the bunch density gradient in self-amplified spontaneous emission (SASE), including the role of coherent spontaneous emission (CSE) in the evolution of the free-electron laser (FEL) process. In the exponential gain regime, the authors solve the coupled Maxwell-Vlasov equations and extend the linear theory to a bunched beam with energy spread. A time-dependent, nonlinear simulation algorithm is used to study the CSE effect and the nonlinear evolution of the radiation pulse.
- Published
- 2000
32. A semi-classical treatment of channeling radiation reaction
- Author
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Ronald D. Ruth, Pisin Chen, and Zhirong Huang
- Subjects
Physics ,Nuclear and High Energy Physics ,Rate equation ,Radiation ,Accelerators and Storage Rings ,Power law ,Relativistic particle ,Transverse plane ,Radiation damping ,Quantum mechanics ,Quantum electrodynamics ,Pitch angle ,Instrumentation ,Quantum - Abstract
A semi-classical formalism is used to calculate the radiation reaction of a relativistic particle in a straight, continuous focusing system. Due to the absence of quantum excitation in such a focusing system, the radiation damping rate of the transverse action obtained using this formalism agrees exactly with the result from the classical Lorentz-Dirac radiation reaction equation. In the limit where the pitch angle of the particle is much smaller than the radiation opening angle, the transverse action damps exponentially with an energy-independent rate that is much faster than the energy decay rate. In the opposite limit, both the transverse action and the energy damp with power laws and their relative rates are comparable. The general time-dependence of the transverse action damping and the energy decay are obtained analytically from these rate equations.
- Published
- 1996
33. Analysis on Temperature Character of CFB Bench When Cocombustion of Oil Shale and Its Semi-Coke
- Author
-
Baizhong, Sun, primary, Lei, Shi, additional, Zhirong, Huang, additional, Qing, Wang, additional, and Shaohua, Li, additional
- Published
- 2012
- Full Text
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