Resistive wall wakefields of short bunches at cryogenic temperatures

Stupakov, Gennady; Bane, K.; Emma, P.; Podobedov, B.

doi:10.1103/physrevstab.18.034402

Cited by 20 publications

(15 citation statements)

References 8 publications

(22 reference statements)

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“…[7]). Known surface impedance models include dc [2], ac [1], and anomalous skin models of wall resistance [8], all of which can also be found in the classic paper of Reuter and Sondheimer [9]; other surface impedance models developed for accelerator physics applications are a model of wall roughness [10], and one for a pipe with small, periodic corrugations [11].…”

Section: A Round Geometrymentioning

confidence: 99%

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Using surface impedance for calculating wakefields in flat geometry

Bane

Stupakov

2015

Phys. Rev. ST Accel. Beams

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Beginning with Maxwell's equations and assuming only that the wall interaction can be approximated by a surface impedance, we derive formulas for the generalized longitudinal and transverse impedance in flat geometry, from which the wakefields can also be obtained. From the generalized impedances, by taking the proper limits, we obtain the normal longitudinal, dipole, and quad impedances in flat geometry. These equations can be applied to any surface impedance, such as the known dc, ac, and anomalous skin models of wall resistance, a model of wall roughness, or one for a pipe with small, periodic corrugations. We show that, for the particular case of dc wall resistance, the longitudinal impedance obtained here agrees with a known result in the literature, a result that was derived from a very general formula by Henke and Napoly.

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Section: A Round Geometrymentioning

confidence: 99%

“…(15), has previously been applied to LCLS-II undulator parameters, taking the surface impedance to represent wall resistance and roughness [10], and recently to represent wall resistance at cryogenic temperatures, by using an anomalous skin effect surface impedance [8].…”

Section: Application To Lcls-ii Undulator Beam Pipementioning

confidence: 99%

Using surface impedance for calculating wakefields in flat geometry

Bane

Stupakov

2015

Phys. Rev. ST Accel. Beams

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“…[41,80], which is a Pr-based cryogenic device having period λ u ¼ 9 mm, and strength K ¼ 1.8. We note that this undulator has a narrow gap, which introduces problems with resistive wall impedance [81]; this is mitigated by the use of microbunching in the ESASE approach. This scenario yields excellent FEL coupling at 0.155 Å (80 keV), with a predicted 3D gain length of 77 cm [82] (implying ρ ¼ 5.3 × 10 −4 ), a result borne out in the simulation shown in Fig.…”

Section: Arriving At An X-ray Fel: Physics Issues and Simulatiomentioning

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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“…When relativistic electron beams pass through metallic pipes (or plates) with corrugations or dielectric structures, electromagnetic waves (wakefields) that propagate with the beams are excited. Such quasi-single frequency radiation on the one hand is a promising candidate for intense THz source (see, for example [1][2][3]); on the other hand it may be used to manipulate electron beam longitudinal phase space through the interaction between the electron beam and the electromagnetic waves inside the structure (see, for example [4][5][6]).…”

Section: Introductionmentioning

confidence: 99%

Time-resolved measurement of quadrupole wakefields in corrugated structures

Jiang

et al. 2016

Phys. Rev. Accel. Beams

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Corrugated structures have recently been widely used for manipulating electron beam longitudinal phase space and for producing THz radiation. Here we report on time-resolved measurements of the quadrupole wakefields in planar corrugated structures. It is shown that while the timedependent quadrupole wakefield produced by a planar corrugated structure causes significant growth in beam transverse emittance, it can be effectively canceled with a second corrugated structure with orthogonal orientation. The strengths of the time-dependent quadrupole wakefields for various corrugated structure gaps are also measured and found to be in good agreement with theories. Our work should forward the applications of corrugated structures in many accelerator based scientific facilities.

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Resistive wall wakefields of short bunches at cryogenic temperatures

Cited by 20 publications

References 8 publications

Using surface impedance for calculating wakefields in flat geometry

Using surface impedance for calculating wakefields in flat geometry

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

Time-resolved measurement of quadrupole wakefields in corrugated structures

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