Research and development toward a 4.5−1.5 Å linac coherent light source (LCLS) at SLAC

Tatchyn, R.; Arthur, John R.; Baltay, M.; Bane, K.; Boyce, R.; Cornacchia, M.; Cremer, T.; Fisher, A.; Hahn, Sang June; Hernández, Michael; Loew, G.A.; Miller, R.H.; Nelson, W.R.; Nuhn, H.‐D.; Palmer, D.T.; Paterson, J. M.; Raubenheimer, T.O.; Weaver, J. N.; Wiedemann, Helmut; Winick, H.; Pellegrini, C.; Travish, G.; Scharlemann, E.T.; Caspi, S.; Fawley, William M.; Halbach, K.; Kim, K.-J.; Schlueter, R.; Xie, Ming; Meyerhofer, D. D.; Bonifacio, R.; Salvo, Luc

doi:10.1016/0168-9002(96)00042-3

Cited by 81 publications

(16 citation statements)

References 32 publications

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“…For example, in one version of the Linac Coherent Light Source (LCLS) project at SLAC, a project that intends to use the SLAC linac as a driver for a very short wave-length FEL, the peak current is 5 kA and the longitudinal bunch shape is non-Gaussian (somewhat rectangular) with an rms length of 20pm (1). Under such conditions the normally weak resistive wall wakefields of a beam tube can be strong, comparable in strength, for example, to those of accelerating cavities of the same beam tube radius.…”

Section: Introductionmentioning

confidence: 99%

The Short-Range Resistive Wall Wakefields

Bane¹,

Sands²

1996

AIP Conference Proceedings

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Abstract. In an accelerator when the bunch length becomes comparable to a characteristic distance S O , one which depends on the radius and the conductivity of the beam tube and in typical structures is on the order of tens of microns, the usual formulas for the resistive wall wakefield do not apply. In this report we derive the short-range resistive wall wakefields of an ultra-relativistic point particle in a metallic, cylindrical tube, both for a model in which the wall conductivity is taken to be independent of frequency and for one in which a frequency dependence is included. On this scale the wakefield is found to be dominated by a damped, high frequency resonator component. For the caSe of constant conductivity the resonant frequency is given by w = &c/so and the &-factor equals &/2. We provide a physical model to explain these results. For the cme of a frequency dependent conductivity the resonator parameters depend also on the relaxation time of the metal T . For CT/SO 2 0.5 the frequency w FZI d w , with w, the plasma frequency of the free electrons in the metal and b the tube we are interested in the wakefield of a short bunch, by which we mean that the bunch length is comparable to the characteristic distance (see, e.g. Ref. 2) with c the speed of light, b the lube radius, and u the conductivity of the metallic walls. For copper at room temperature* u = 5.8 x 1017 s-', For a copper tube with b = 1 cm, SO = 20pm. Although in accelerators the bunch length is normally much larger than this value the above LCLS example falls within the short bunch category if the tube radius is comparable to 1 cm. Note also that, €or a given bunch length, as we increase b we will also increase so. For the above example, if we increase b to 10 cm then so becomes 93pm.The conductivity of a metal is not independent of frequency. In the presence of oscillating fields Ohm's law becomes J = C E with (3) with w the frequency of oscillation and r the relaxation time of the metal. We note that it is only at higher frequencies that 6 (which we will call the radius, and the l / e damping time becomes 4r. Finally, we calculate the wakefield and loss factor of a short Gaussian bunch. ac conductivity) differs significantly from u (the dc conductivity). For copper at room ternperatixe the re!axatinE time r = 2.7 x s ~r c7 = e..~pm. [Note that for Ag, T = 4.0 x s. Note also that 'UT = e, with 6 the average velocity of the free electrons in the metal and the mean free path between collisions.] Let us introduce the dimensionless relaxation factor I' = cr/so. For a 1 cm copper tube I' = 0.4. Therefore, for this example, for frequencies w -c/so, the second term in the denominator of Eq. (2), in amplitude, becomes comparable to the first term; we might therefore expect the short range iic wakefield to be noticeably different from the short range dc wake.Down to what length scale do we expect that our calculations are valid? An important assumption in all our calculations is that Ohm's law applies in the metallic walls. One effect, the anom...

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Section: Introductionmentioning

confidence: 99%

The Short-Range Resistive Wall Wakefields

Bane¹,

Sands²

1996

AIP Conference Proceedings

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“…There are, in the world, intensive studies on photocathode electron guns for high-brightness beams, which is a key component of X-ray free-electron lasers, 14,15) compact accelerators for medical, industrial, and scientific uses. [16][17][18] Combining the ERL with a photocathode electron gun, we can obtain a high-brightness electron beam, whose emittance is smaller than that of storage rings.…”

Section: Energy-recovery Linacmentioning

confidence: 99%

Proposal of Nondestructive Radionuclide Assay Using a High-Flux Gamma-Ray Source and Nuclear Resonance Fluorescence

Hajima

Hayakawa

Kikuzawa

et al. 2008

J. Nucl. Sci. Technol.

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A nondestructive assay system for radioactive waste management is proposed. The system utilizes nuclear resonance fluorescence triggered by a quasi-monochromatic high-flux gamma ray generated from the Compton scattering of laser photons by relativistic electrons. We employ an energy-recovery linac as an electron source and a mode-locked fiber laser followed by a laser supercavity as a photon source. The combination of these novel technologies realizes a gamma-ray flux much higher than existing sources using electron storage rings. The proposed gamma-ray source produces a quasi-monochromatic gamma ray with a flux of 10 10 /s/keV, which is high enough for industrial applications such as the nondestructive analysis of radionuclides in nuclear waste and the interrogation of fissile material in cargoes. The nuclear resonance fluorescence triggered by quasi-monochromatic gamma rays provides a versatile method of nondestructive analysis of both radioactive and stable nuclides.

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“…This dependency is illustrated by the LCLS design study recently undertaken at SLAC [3], which projects a net emittance of approximately 1.5 mm-mr at the undulator entrance. The LCLS parameters from this study are contrasted in Table 1 with those from an earlier study [4], which presupposed a net attainable emittance of 1 mm-mr.…”

Section: Introductionmentioning

confidence: 79%

“…Third, the PMQ pieces can be made with l Q >t PM and extended (below the pole faces) along distances of several periods. Here, s ≥w smin , and the PMQ pieces could be either affixed to the vacuum duct and tuned with linear wire currents [4], or moved into the gap laterally with high-precision mechanical movers. Finally, the dipole structure could be implemented with periodic drift spaces [12], and the PMQ pieces could be installed thereinto, again with mechanical or wire-current tuning of their gradients.…”

Section: A High-field Lcls Undulator Design With Strong Planar-pmmentioning

confidence: 99%

“…For Q ≥45 T/m, alternative techniques need to be employed [7][8][9][10]. In this paper, the planar-PM multipole technology proposed in recent years [7,8] is explored as a basis for a strong-focusing LCLS undulator field design [4,11]. The r&d associated with this work anticipates the eventual development of photocathode (pc) rf guns and linac-based compressor/transport systems that will deliver emittances of 1 mm-mr or less to the LCLS insertion device.…”

Section: Introductionmentioning

confidence: 99%

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Design features of a planar hybrid/permanent magnet strong-focusing undulator for free electron laser (FEL) and synchrotron radiation (SR) applications

Tatchyn

Proceedings of the 1997 Particle Accelerator Conference (Cat. No.97CH36167)

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Insertion devices for Ångstrom-wavelength Free Electron Laser (FEL) amplifiers driven by multi-GeV electron beams generally require distributed focusing substantially stronger than their own natural focusing fields. Over the last several years a wide variety of focusing schemes and configurations have been proposed for undulators of this class, ranging from conventional current-driven quadrupoles external to the undulator magnets to permanent magnet (PM) lattices inserted into the insertion device gap. In this paper we present design studies of a flexible high-field hybrid/PM undulator with strong superimposed planar PM focusing proposed for a 1.5 Angstrom Linac Coherent Light Source (LCLS) driven by an electron beam with a 1 mm-mr normalized emittance. Attainable field parameters, tuning modes, and potential applications of the proposed structure are discussed.

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Research and development toward a 4.5−1.5 Å linac coherent light source (LCLS) at SLAC

Cited by 81 publications

References 32 publications

The Short-Range Resistive Wall Wakefields

The Short-Range Resistive Wall Wakefields

Proposal of Nondestructive Radionuclide Assay Using a High-Flux Gamma-Ray Source and Nuclear Resonance Fluorescence

Design features of a planar hybrid/permanent magnet strong-focusing undulator for free electron laser (FEL) and synchrotron radiation (SR) applications

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