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D.C. Nguyen

First Name: D.

Middle Name: C.

Last Name: Nguyen

Full Name: D.C. Nguyen

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10 papers
title: Compact double-bunch x-ray free electron lasers for fresh bunch self-seeding and harmonic lasing
format: journal article
publisher: Physical Review Accelerators and Beams
year: 2017
5 authors: C. Emma | Y. Feng | D.C. Nguyen | A. Ratti | C. Pellegrini
abstract: This paper presents a novel method to improve the longitudinal coherence, efficiency and maximum photon energy of x-ray free electron lasers (XFELs). The method is equivalent to having two separate concatenated XFELs. The first uses one bunch of electrons to reach the saturation regime, generating a high power self-amplified spontaneous emission x-ray pulse at the fundamental and third harmonic. The x-ray pulse is filtered through an attenuator/monochromator and seeds a different electron bunch in the second FEL, using the fundamental and/or third harmonic as an input signal. In our method we combine the two XFELs operating with two bunches, separated by one or more rf cycles, in the same linear accelerator. We discuss the advantages and applications of the proposed system for present and future XFELs.
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title: Photoinjector design for the LCLS
format: conference proceeding
conference: FEL 2001 23rd
year: 2002
16 authors: P.R. Bolton | Clendenin, J. E. | Dowell, D. H. | M. Ferrario | A.S. Fisher | Gierman, S. M. | Kirby, R. E. | P. Krejcik | Limborg, C. G. | Mulhollan, G. A. | D. C. Nguyen | D. T. Palmer | J.B. Rosenzweig | Schmerge, J. F. | L. Serafini | X.J. Wang
abstract: The design of the Linac Coherent Light Source assumes that a low-emittance, 1 nC, 10 ps beam will be available for injection into the 15 GeV linac. The proposed RF photocathode injector that will meet this requirement is based on a 1.6-cell S-band RF gun equipped with an emittance-compensating solenoid. The booster accelerator with a gradient of 25 MV/m is positioned at the beam waist coinciding with the first emittance maximum, i.e., the "new working point." The UV pulses required for cathode excitation will be generated by tripling the output of a Ti:sapphire laser system. Details of the design and the supporting simulations are presented. (12 References).
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title: Initial gain measurements of an 800 nm SASE FEL, VISA
format: conference proceeding
conference: FEL 2000 22nd
year: 2001
26 authors: P. Frigola | A. Murokh | P. Musumeci | C. Pellegrini | Sven Reiche | J.B. Rosenzweig | A. Tremaine | M. Babzien | I. Ben-Zvi | E. Johnson | R. Malone | G. Rakowsky | Skaritka, J. | X. J. Wang | K. A. Van Bibber | L. Bertolini | J. M. Hill | G.P. Le Sage | M. Libkind | A. Toor | R. Carr | M. Cornacchia | L. Klaisner | H. D. Nuhn | Ruland, R. | D. C. Nguyen
abstract: The visible to infrared SASE amplifier (VISA) FEL is designed to obtain high gain at a radiation wavelength of 800 nm. The FEL uses the high brightness electron beam of the accelerator test facility (ATF), with energy of 72 MeV. VISA uses a novel, 4 m long, strong focusing undulator with a gap of 6 mm and a period of 1.8 cm. To obtain large gain the beam and undulator axis have to be aligned to better than 5 mu m. Results from initial measurements on the alignment, gain, and spectrum will be presented and compared to theoretical calculations and simulations. (10 References).
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title: New design study and related experimental program for the LCLS RF photoinjector
format: conference proceeding
conference: EPAC 2000
year: 2000
11 authors: M. Ferrario | P.R. Bolton | Clendenin, J. E. | Dowell, D. H. | Gierman, S. M. | M. E. Hernandez | D. C. Nguyen | D. T. Palmer | J.B. Rosenzweig | Schmerge, J. F. | L. Serafini
abstract: We report the results of a recent beam dynamics study, motivated by the need to redesign the LCLS photoinjector, that lead to the discovery of a new effective working point for a split RF photoinjector. We consider the emittance compensation regime of a space charge beam: by increasing the solenoid strength, the emittance evolution shows a double minimum behavior in the drifting region. If the booster is located where the relative emittance maximum and the envelope waist occur, the second emittance minimum can be shifted to the booster exit and frozen at a very low level (0.3 mm-mrad for a 1 nC flat top bunch), to the extent that the invariant envelope matching conditions are satisfied. Standing Wave Structures or alternatively Traveling Wave Structures embedded in a Long Solenoid are both candidates as booster linac. A careful measurement of the emittance evolution as a function of position in the drifting region is necessary to verify the computation and to determine experimentally the proper position of the booster cavities. The new design study and supporting experimental program under way at the SLAC Gun Test Facility are discussed.
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title: Status and initial commissioning of a high gain 800 nm SASE FEL
format: conference proceeding
conference: FEL 1999 21st
year: 2000
22 authors: A. Tremaine | Pedro Frigola | A. Murokh | P. Musumeci | C. Pellegrini | J.B. Rosenzweig | M. Babzien | Ben-Zvi, I. | E. Johnson | R. Malone | G. Rakowsky | Skaritka, J. | X.J. Wang | Yu, L. H. | Van Bibber, K. A. | J.M. Hill | G.P. Le Sage | R. Carr | M. Cornacchia | Nuhn, H. D. | Ruland, R. | D. C. Nguyen
abstract: We describe the status and initial commissioning of the visible to infrared SASE amplifier (VISA) experiment. VISA uses a strong focusing 4 m undulator, the Brookhaven National Laboratory ATF linac with an energy of 72 MeV, and a photoinjector electron source. The VISA fundamental radiation wavelength is near 800 nm and the power expected at saturation is near 60 MW. Power, angular and spectral measurements are planned for the VISA radiation and these results will be analyzed and compared with SASE FEL theory and computer simulation. In addition, the induced electron beam micro-bunching will be measured using coherent transition radiation. (12 References).
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title: Photon beam diagnostics for VISA FEL
format: conference proceeding
conference: PAC 1999
year: 1999
17 authors: A. Murokh | C. Pellegrini | J.B. Rosenzweig | Pedro Frigola | P. Musumeci | A. Tremaine | M. Babzien | Ben-Zvi, I. | A. Doyuran | E. Johnson | Skaritka, J. | X.J. Wang | Van Bibber, K. A. | J.M. Hill | G.P. Le Sage | D. C. Nguyen | M. Cornacchia
abstract: The VISA (Visible to Infrared SASE Amplifier) project is designed to be a SASE-FEL driven to saturation in the sub-micron wavelength region. Its goal is to test various aspects of the existing theory of self-amplified spontaneous emission, as well as numerical codes. Measurements include: angular and spectral distribution of the FEL light at the exit and inside of the undulator; electron beam micro-bunching using CTR; single-shot time resolved measurements of the pulse profile, using an auto-correlation technique and FROG algorithm. The diagnostics are designed to provide maximum information on the physics of the SASE-FEL process, to ensure a close comparison of the experimental results with theory and simulations. (9 References).
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title: A measurement of high gain SASE FEL induced electron beam micro-bunching using coherent transition radiation
format: conference proceeding
conference: PAC 1999
year: 1999
9 authors: A. Tremaine | S. Anderson | Pedro Frigola | M. Hogan | A. Murokh | C. Pellegrini | J.B. Rosenzweig | D. C. Nguyen | Sheffield, R.
abstract: Coherent transition radiation (CTR) was used to study the longitudinal modulations of an electron beam exiting the UCLA/LANL high gain SASE FEL. The induced longitudinal micro-bunching of the electron beam at the exit of the undulator was measured with a frequency domain technique using the CTR emitted when this beam strikes a thin conducting foil. Formalisms for both CTR and SASE theories are related using the simulation code GINGER in which the SASE FEL gain of the output radiation and the micro-bunching of the electron beam are given. Experimental results from the CTR measurement will show the limit of standard transition radiation theory is being approached and new analysis is needed. (8 References).
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title: Measured free-electron laser microbunching using coherent transition radiation
format: conference proceeding
conference: FEL 1998 20th
year: 1999
9 authors: A. Tremaine | J.B. Rosenzweig | S. Anderson | Pedro Frigola | M. Hogan | A. Murokh | C. Pellegrini | D. C. Nguyen | Sheffield, R.
abstract: The microbunch distribution of an electron beam exiting a SASE free-electron laser has been measured using the emitted coherent transition radiation (CTR) produced from a thin aluminum foil placed at the end of the undulator. The wavelength of the coherent transition radiation is shown to be the same as the FEL wavelength, and thus a measure of the beam microbunch spacing. Also, the study of the CTR linewidth and angular acceptance of the radiation captured are shown to be derived from this coherent radiative process. Scattering effects on the forward emitted transition radiation from the electron beam traversing an aluminum foil are also considered. (11 References).
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title: Measurements of gain larger than 10(5) at 12 mu m in a self-amplified spontaneous-emission free-electron laser
format: journal article
publisher: Physical Review Letters
year: 1998
13 authors: M. Hogan | C. Pellegrini | J.B. Rosenzweig | S. Anderson | Pedro Frigola | A. Tremaine | C. Fortgang | D. C. Nguyen | R. L. Sheffield | J. Kinross-Wright | A. A. Varfolomeev | S. Tolmachev | R. Carr
abstract: We report measurements of very large output intensities corresponding to a gain larger than 10/sup 5/ for a single pass free-electron laser operating in the self-amplified spontaneous emission (SASE) mode at 12 mu m. We also report the observation and analysis of intensity fluctuations of the SASE radiation intensity in the high-gain regime. The results are compared with theoretical predictions and simulations. (18 References).
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title: Observation of Self-Amplified Spontaneous-Emission-Induced Electron-Beam Microbunching Using Coherent Transition Radiation
format: journal article
publisher: Physical Review Letters
year: 1998
9 authors: A. Tremaine | J.B. Rosenzweig | S. Anderson | Pedro Frigola | M. Hogan | A. Murokh | C. Pellegrini | D. C. Nguyen | R. L. Sheffield
abstract: We report the measurement of electron-beam microbunching at the exit of a self-amplified spontaneous-emission free-electron laser (SASE FEL), by observation of coherent transition radiation (CTR). The CTR was found to have an angular spectrum much narrower than spontaneous transition radiation and a narrow-band frequency spectrum. The central frequency of the fundamental CTR spectrum is found to differ slightly from that of the SASE, a finding in disagreement with previously invoked CTR theory. The CTR measurement establishes the uniformity of microbunching in the transverse dimension, indicating the SASE FEL operates in a dominant transverse mode.
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