Photoinjector design for the LCLs

Bolton, Paul R.; Clendenin, J. E.; Dowell, D.H.; Ferrario, M.; Fisher, A.; Gierman, S.M.; Kirby, R. E.; Krejcik, P.; Limborg, C.; Mulhollan, G. A.; Nguyen, Dinh C.; Palmer, D.T.; Rosenzweig, James; Schmerge, J. F.; Serafini, L.; Wang, X. J.

doi:10.1016/s0168-9002(02)00331-5

Cited by 12 publications

(7 citation statements)

References 11 publications

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“…Emittances measured at low charge (< 350 pC) with relatively short pulse lengths and Gaussian pulse shapes will be presented here. 3 The results are in agreement with PARMELA simulations. This agreement suggests that PARMELA can be used to verify the new LCLS photoinjector design [3].…”

Section: Introductionsupporting

confidence: 84%

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Transverse-emittance measurements on an S-band photocathode RF electron gun

Schmerge¹,

Bolton²,

Clendenin³

et al. 2002

Nuclear Instruments and Methods in Physics Research Section A:

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Section: Introductionsupporting

confidence: 84%

“…3 The results are in agreement with PARMELA simulations. This agreement suggests that PARMELA can be used to verify the new LCLS photoinjector design [3].…”

Section: Introductionsupporting

confidence: 84%

Transverse-emittance measurements on an S-band photocathode RF electron gun

Schmerge¹,

Bolton²,

Clendenin³

et al. 2002

Nuclear Instruments and Methods in Physics Research Section A:

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“…This 1D prediction is of course approximate, due to the 3D nature of the pulse expansion. We concentrate first on the example of I b ¼ 100 A, to draw connection to the original LCLS photoinjector design, which remains a point of reference in the electron source field [53]. Specifically, the original proposal for the LCLS photoinjector employed approximately constant laser intensity inside of a cylindrical temporal-radial boundary, launching a nearly uniform cylinder of charge from the photocathode [29].…”

Section: Beam Dynamics: Operation In the Blowout Regimementioning

confidence: 99%

Next generation high brightness electron beams from ultrahigh field cryogenic rf photocathode sources

Rosenzweig

Cahill

Dolgashev

et al. 2019

Phys. Rev. Accel. Beams

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Recent studies of the performance of radio-frequency (rf) copper cavities operated at cryogenic temperatures have shown a dramatic increase in the maximum achievable surface electric field. We propose to exploit this development to enable a new generation of photoinjectors operated at cryogenic temperatures that may attain, through enhancement of the launch field at the photocathode, a significant increase in fivedimensional electron beam brightness. We present detailed studies of the beam dynamics associated with such a system, by examining an S-band photoinjector operated at 250 MV=m peak electric field that reaches normalized emittances in the 40 nm-rad range at charges (100-200 pC) suitable for use in a hard x-ray free-electron laser (XFEL) scenario based on the LCLS. In this case, we show by start-to-end simulations that the properties of this source may give rise to high efficiency operation of an XFEL, and permit extension of the photon energy reach by an order of magnitude, to over 80 keV. The brightness needed for such XFELs is achieved through low source emittances in tandem with high current after compression. In the XFEL examples analyzed, the emittances during final compression are preserved using microbunching techniques. Extreme low emittance scenarios obtained at pC charge, appropriate for significantly extending temporal resolution limits of ultrafast electron diffraction and microscopy experiments, are also reviewed. While the increase in brightness in a cryogenic photoinjector is mainly due to the augmentation of the emission current density via field enhancement, further possible increases in performance arising from lowering the intrinsic cathode emittance in cryogenic operation are also analyzed. Issues in experimental implementation, including cavity optimization for lowering cryogenic thermal dissipation, external coupling, and cryocooler system, are discussed. We identify future directions in ultrahigh field cryogenic photoinjectors, including scaling to higher frequency, use of novel rf structures, and enabling of an extremely compact hard x-ray FEL.

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“…If the beam is properly matched out of the gun into the booster linac by adjusting a beam waist at the linac entrance and regulating the linac gradient in such a way as to fulfill the invariant envelope condition, the final emittance at the linac exit is minimized. Advanced designs of high brightness injectors for X-ray free electron lasers, like the Lincac Coherent Light Source (LCLS) injector, make full use of these theoretical criteria, achieving the best emittances in simulation [Bolton et al (2002)l.…”

Section: Longitudinal Charge Distribution Of Electron Beam Bunch [Bnlmentioning

confidence: 99%

Femtosecond Beam Generation

Umstadter

Uesaka

Hosokai

2005

Femtosecond Beam Science

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The first issue in the field of terawatt (TW) lasers is the oscillator principle for generating ultrashort pulses.Conventional pulsed lasers are based on the Q-switching principle. The laser cavity is made of a gain medium and a switching element that triggers pulse emission. The Q switch, which can be either acousto-optical or electro-optical (the Pockels cell principle), is a variable loss element (oscillator Q modulator) and usually exhibits a switching time in the nanosecond range. Such devices do not generate pulses below the nanosecond range.

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Photoinjector design for the LCLs

Cited by 12 publications

References 11 publications

Transverse-emittance measurements on an S-band photocathode RF electron gun

Transverse-emittance measurements on an S-band photocathode RF electron gun

Next generation high brightness electron beams from ultrahigh field cryogenic rf photocathode sources

Femtosecond Beam Generation

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