Using the longitudinal space charge instability for generation of vacuum ultraviolet and x-ray radiation

Schneidmiller, E.A.; Yurkov, M.V.

doi:10.1103/physrevstab.13.110701

Cited by 38 publications

(65 citation statements)

References 28 publications

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“…This complements FEL-based strategies to generate attosecond x rays (Ref. [16] and References therein). Our scheme has the advantage that the attosecond pulses have a defined phase-relation to the optical laser and that it can be employed at any FEL with moderate cost and minimal impact on other experiments.…”

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confidence: 99%

High-order harmonic generation enhanced by XUV light

et al. 2011

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The combination of high-order harmonic generation (HHG) with resonant xuv excitation of a core electron into the transient valence vacancy that is created in the course of the HHG process is investigated theoretically. In this setup, the first electron performs a HHG three-step process whereas, the second electron Rabi flops between the core and the valence vacancy. The modified HHG spectrum due to recombination with the valence and the core is determined and analyzed for krypton on the 3d → 4p resonance in the ion. We assume an 800 nm laser with an intensity of about 10 14 W cm 2 and xuv radiation from the Free Electron Laser in Hamburg (FLASH) with an intensity in the range 10 13 -10 16 W cm 2 . Our prediction opens perspectives for nonlinear xuv physics, attosecond x rays, and HHG-based spectroscopy involving core orbitals. c 2018 Optical Society of America OCIS codes: 190.2620, 140.2600 High-order harmonic generation (HHG) by atoms in intense optical laser fields is a fascinating phenomenon and a versatile tool; it has spawned the field of attoscience, is used for spectroscopy, and serves as a light source in many optical laboratories [1]. Present-day theory of HHG largely gravitates around the single-active electron (SAE) approximation and the restriction to HHG from valence electrons [1][2][3][4].Several extensions to the SAE view of HHG have been investigated previously. A two-electron scheme was considered that uses sequential double ionization by an optical laser with a subsequent nonsequential double recombination; in helium this leads to a second plateau with about 12 orders of magnitude lower yield than the primary HHG plateau [5]. Two-color HHG (optical plus xuv light) has been studied in a one-electron model [6] and with many-electron effects included by a frequency-dependent polarization [7]; the xuv radiation assists thereby in the ionization process leading to an overall increased yield [6] and the emergence of a new plateau [7], the latter, however, at a much lower yield. The above schemes suffer from tiny conversion efficiency beyond the conventional HHG cutoff (maximum photon energy).We propose an efficient two-electron scheme for a HHG process manipulated by intense xuv light from the newly constructed free electron lasers (FEL)-e.g., the Free Electron Laser in Hamburg (FLASH). Our principal idea is sketched in Fig. 1. In the parlance of the three-step model [2,3], HHG proceeds as follows: (a) the atomic valence is tunnel ionized; (b) the liberated electron propagates freely in the electric field of the optical laser; (c) the direction of the optical laser field is reversed and the electron is driven back to the ion and eventually recombines with it emitting HHG radiation. The excursion time of the electron from the ion is approxi- mately 1 fs for typical 800 nm optical laser light. During this time, one can manipulate the ion such that the returning electron sees the altered ion as depicted in Fig. 1. Then, the emitted HHG radiation bears the signature of the change. Perfectly suited for t...

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High-order harmonic generation enhanced by XUV light

et al. 2011

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“…Though typically small enough not to affect LCLS lasing, SES limits more advanced schemes such as high gain harmonic generation [26], harmonic lasing [27,28], longitudinal space charge amplifiers [29,30], and dispersive noise suppression [31,32]. Here we report LCLS's first measurements of SES of the accelerated beam, as well as SES dependence on the laser heater and MBI.…”

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confidence: 99%

Time-resolved imaging of the microbunching instability and energy spread at the Linac Coherent Light Source

Ratner

Behrens

Ding

et al. 2015

Phys. Rev. ST Accel. Beams

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The microbunching instability (MBI) is a well-known problem for high brightness electron beams and has been observed at accelerator facilities around the world. Free-electron lasers (FELs) are particularly susceptible to MBI, which can distort the longitudinal phase space and increase the beam's slice energy spread (SES). Past studies of MBI at the Linac Coherent Light Source (LCLS) relied on optical transition radiation to infer the existence of microbunching. With the development of the x-band transverse deflecting cavity (XTCAV), we can for the first time directly image the longitudinal phase space at the end of the accelerator and complete a comprehensive study of MBI, revealing both detailed MBI behavior as well as insights into mitigation schemes. The fine time resolution of the XTCAV also provides the first LCLS measurements of the final SES, a critical parameter for many advanced FEL schemes. Detailed MBI and SES measurements can aid in understanding MBI mechanisms, benchmarking simulation codes, and designing future high-brightness accelerators.

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“…Shot noise suppression may also aid other areas of accelerator physics, for example increasing efficiency in cooling relativistic beams [16,17]. In general, improved understanding and control of shot noise will aid in the design of future SASE FELs, and the microbunching instability itself may prove useful as a novel radiation source [18].…”

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Observation of Shot Noise Suppression at Optical Wavelengths in a Relativistic Electron Beam

Ratner

Stupakov

2012

Phys. Rev. Lett.

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Control of collective properties of relativistic particles is increasingly important in modern accelerators. In particular, shot noise affects accelerator performance by driving instabilities or by competing with coherent processes. We present experimental observations of shot noise suppression in a relativistic beam at the Linac Coherent Light Source. By adjusting the dispersive strength of a chicane, we observe a decrease in the optical transition radiation emitted from a downstream foil. We show agreement between the experimental results, theoretical models, and 3D particle simulations.

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Using the longitudinal space charge instability for generation of vacuum ultraviolet and x-ray radiation

Cited by 38 publications

References 28 publications

High-order harmonic generation enhanced by XUV light

High-order harmonic generation enhanced by XUV light

Time-resolved imaging of the microbunching instability and energy spread at the Linac Coherent Light Source

Observation of Shot Noise Suppression at Optical Wavelengths in a Relativistic Electron Beam

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