4 papers

title:	The design for the LCLS RF photoinjector
format:	conference procceeding
conference:	20th International Free Electron Laser Conference
year:	1999
16 authors:	Alley, R. | Bharadwaj, V. | Clendenin, J. E. | P. Emma | Fisher, A. | Frisch, J. | Kotseroglou, T. | R. H. Miller | D. T. Palmer | Schmerge, J. F. | Sheppard, J. C. | Woodley, M. | Yeremian, A. D. | J. B. Rosenzweig | D. Meyerhofer | L. Serafini
abstract:	We report on the design of the RF photoinjector of the Linac Coherent Light Source. The RF photoinjector is required to produce a single 150 MeV bunch of similar to 1 nC and similar to 100 A peak current at a repetition rate of 120 Hz with a normalized rms transverse emittance of similar to 1 pi mm-mrad. The design employs a 1.6-cell S-band RF gun with an optical spot size at the cathode of a radius of similar to 1 mm and a pulse duration with an rms sigma of similar to 3 ps. The peak RF field at the cathode is 150 MV/m with extraction 57 degrees ahead of the RF peak. A solenoidal field near the cathode allows the compensation of the initial emittance growth by the end of the injection linac. Spatial and temporal shaping of the laser pulse striking the cathode will reduce the compensated emittance even further. Also, to minimize the contribution of the thermal emittance from the cathode surface, while at the same time optimizing the quantum efficiency, the laser wavelength for a Cu cathode should be tunable around 260 nm. Following the injection linac the geometric emittance simply damps linearly with energy growth. PARMELA simulations show that this design will produce the desired normalized emittance, which is about a factor of two lower than has been achieved to date in other systems. In addition to low emittance, we also aim for laser amplitude stability of 1% in the UV and a timing jitter in the electron beam of 0.5 ps rms, which will lead to less than 10% beam intensity fluctuation after the electron bunch is compressed in the main linac.
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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:	R. Tatchyn | J. Arthur | M. Baltay | K. Bane | R. Boyce | M. Cornacchia | T. Cremer | A. Fisher | S. J. Hahn | M. Hernandez | G. Loew | R. Miller | W. R. Nelson | H. D. Nuhn | D. Palmer | J. Paterson | T. Raubenheimer | J. Weaver | H. Wiedemann | H. Winick | C. Pellegrini | G. Travish | E. T. Scharlemann | S. Caspi | W. Fawley | K. Halbach | K. J. Kim | R. Schlueter | M. Xie | D. Meyerhofer | R. Bonifacio | L. De Salvo
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:	Progress on Plasma Lens Experiments at the Final Focus Test Beam
format:	conference procceeding
conference:	1995 Particle Accelerator Conference
year:	1995
34 authors:	P. Kwok | Chen, P. | D. B. Cline | Barletta, W. | Berridge, S. | Bugg, W. | Bula, C. | S. Chattopadhyay | Craddock, W. | Hsu, I. | R. Iverson | T. Katsouleas | Lai, P. | Leemans, W. | Liou, R. | McDonald, K. T. | D. Meyerhofer | Nakajima, K. | Nakanishi, H. | Ng, C. K. | Nishida, Y. | Norem, J. | Ogata, A. | J. B. Rosenzweig | Ross, M. | Sessler, A. | Shintake, T. | Spencer, J. | Su, J. J. | Weidemann, A. W. | Westenskow, G. | D. Whittum | Williams, R. | J. Wurtele
abstract:	The proposal to perform a series of plasma lens experiments at the Final Focus Test Beam at SLAC has been described earlier. We report on our progress towards validation of concepts involved in the experiments, including the laser ionized plasma production test, development of the supersonic gas jet as the plasma source, and study on focused beam size measurement techniques. Most importantly, the effects of background events due to plasma lenses in future linear collider detectors, such as that in the NLC, are studied in details and are shown to be within detector tolerances.
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title:	Plasma Lens Experiments at the Final Focus Test Beam
format:	conference procceeding
conference:
year:	1995
33 authors:	Lieu, R. | Barletta, W. | S. Chattopadhyay | Chen, P. | D. B. Cline | Craddock, W. | Gabella, W. | Hsu, I. | R. Iverson | T. Katsouleas | P. Kwok | Lai, P. | Leemans, W. | Liou, R. | D. Meyerhofer | Nakajima, K. | Nakanishi, H. | Ng, C. K. | Nishida, Y. | Norem, J. | Ogata, A. | Rajagopalan, S. | Shintake, T. | J. B. Rosenzweig | Ross, M. | Sessler, A. | Spencer, J. | Su, J. J. | Walker, N. | Westenskow, G. | D. Whittum | Williams, R. | J. Wurtele
abstract:	We intend to carry out a series of plasma lens experiments at the Final Focus Test Beam facility at SLAC. These experiments will be the first to study the focusing of particle beams by plasma focusing devices in the parameter regime of interest for high energy colliders, and is expected to lead to plasma lens designs capable of unprecedented spot sizes. Plasma focusing of positron beams will be attempted for the first time. We will study the effects of lens aberrations due to various lens imperfections. Several approaches will be applied to create the plasma required including laser ionization and beam induced tunneling ionization of a working gas - the latter which has never been observed before. The compactness of our device should prove to be of interest for applications at the SLC and the next generation linear colliders.
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