Schemes and challenges for electron injectors operating in high repetition rate X-ray FELs

Sannibale, F.; Filippetto, D.; Papadopoulos, C.

doi:10.1080/09500340.2011.601328

Cited by 10 publications

(13 citation statements)

References 65 publications

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“…Figure 1 shows a CAD cross section of the cavity with its main components, and Table II contains the VHF gun main design parameters selected to satisfy the requirements in Table I and in Ref. [16]. The resonant copper structure is surrounded by a stainless steel shell that ensures the necessary mechanical rigidity and the proper vacuum envelope.…”

Section: Apex the Advanced Photoinjector Experimentsmentioning

confidence: 99%

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Advanced photoinjector experiment photogun commissioning results

Sannibale¹,

Filippetto²,

Papadopoulos³

et al. 2012

Phys. Rev. ST Accel. Beams

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The Advanced Photoinjector Experiment (APEX) at the Lawrence Berkeley National Laboratory is dedicated to the development of a high-brightness high-repetition rate (MHz-class) electron injector for x-ray free-electron laser (FEL) and other applications where high repetition rates and high brightness are simultaneously required. The injector is based on a new concept rf gun utilizing a normal-conducting (NC) cavity resonating in the VHF band at 186 MHz, and operating in continuous wave (cw) mode in conjunction with high quantum efficiency photocathodes capable of delivering the required charge at MHz repetition rates with available laser technology. The APEX activities are staged in three phases. In phase 0, the NC cw gun is built and tested to demonstrate the major milestones to validate the gun design and performance. Also, starting in phase 0 and continuing in phase I, different photocathodes are tested at the gun energy and at full repetition rate for validating candidate materials to operate in a high-repetition rate FEL. In phase II, a room-temperature pulsed linac is added for accelerating the beam at several tens of MeV to reduce space charge effects and allow the measurement of the brightness of the beam from the gun when integrated in an injector scheme. The installation of the phase 0 beam line and the commissioning of the VHF gun are completed, phase I components are under fabrication, and initial design and specification of components and layout for phase II are under way. This paper presents the phase 0 commissioning results with emphasis on the experimental milestones that have successfully demonstrated the APEX gun capability of operating at the required performance.

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Section: Apex the Advanced Photoinjector Experimentsmentioning

confidence: 99%

“…At the present time, despite some promising results [15], none has demonstrated the necessary set of requirements described in Ref. [16].…”

Section: Introductionmentioning

confidence: 99%

Advanced photoinjector experiment photogun commissioning results

Sannibale¹,

Filippetto²,

Papadopoulos³

et al. 2012

Phys. Rev. ST Accel. Beams

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show abstract

“…Further increasing l would require lower values of E 0 and 0 to meet the blow-out regime conditions [Eq. (1)] resulting in operating points that might not be relevant to applications demanding significant (sub-nC) charge per bunch, e.g., high-averagepower FELs [11,12].…”

Section: Introductionmentioning

confidence: 99%

Formation and acceleration of uniformly filled ellipsoidal electron bunches obtained via space-charge-driven expansion from a cesium-telluride photocathode

Piot

Sun

Maxwell

et al. 2013

Phys. Rev. ST Accel. Beams

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We report the experimental generation, acceleration, and characterization of a uniformly filled electron bunch obtained via space-charge-driven expansion (often referred to as ''blow-out regime'') in an L-band (1.3-GHz) radiofrequency photoinjector. The beam is photoemitted from a cesium-telluride semiconductor photocathode using a short (< 200 fs) ultraviolet laser pulse. The produced electron bunches are characterized with conventional diagnostics and the signatures of their ellipsoidal character are observed. We especially demonstrate the production of ellipsoidal bunches with charges up to $0:5 nC corresponding to a $20-fold increase compared to previous experiments with metallic photocathodes.

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“…A significant improvement would be to use MeV RF guns at higher repetition rates, which can in principle operate at MHz repetition rates [70]. This would require ultrafast lasers with high average power to perform pump-probe experiments at high repetition rates.…”

Section: Discussionmentioning

confidence: 99%

“…This alignment is sufficient when dealing with small molecules, but may not be sufficient for larger molecules. The lower density of highly aligned molecules could in principle be partially compensated with the use of high brightness and high repetition rate electrons guns [43,70], and by the increased contrast in the diffraction pattern of highly aligned molecules [66]. For large molecules such as proteins, adiabatic alignment may provide sufficient alignment for structure retrieval [20,71].…”

Section: Imaging Of Molecules By Electron Diffraction From Impulsivelmentioning

confidence: 99%

Ultrafast imaging of isolated molecules with electron diffraction

Centurion

2016

J. Phys. B: At. Mol. Opt. Phys.

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Recent advances in ultrafast electron diffraction offer the possibility to image isolated molecules with sub-Angstrom spatial resolution in ultrafast time scales. In particular, diffraction from aligned molecules has opened the door to retrieving three-dimensional structures directly from experimental data. In this manuscript we review the progress in ultrafast gas electron diffraction and discuss remaining challenges to achieve a temporal resolution of sub-100 fs, which is needed to observe the nuclear motion in chemical reactions in the gas phase.

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Schemes and challenges for electron injectors operating in high repetition rate X-ray FELs

Cited by 10 publications

References 65 publications

Advanced photoinjector experiment photogun commissioning results

Advanced photoinjector experiment photogun commissioning results

Formation and acceleration of uniformly filled ellipsoidal electron bunches obtained via space-charge-driven expansion from a cesium-telluride photocathode

Ultrafast imaging of isolated molecules with electron diffraction

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