Generation of attosecond soft x-ray pulses in a longitudinal space charge amplifier

Abstract

A longitudinal space charge amplifier (LSCA), operating in soft x-ray regime, was recently proposed. Such an amplifier consists of a few amplification cascades (focusing channel and chicane) and a short radiator undulator in the end. The broadband nature of LSCA supports generation of few-cycle pulses as well as wavelength compression. In this paper we consider an application of these properties of LSCA for generation of attosecond x-ray pulses. It is shown that a compact and cheap addition to the soft x-ray freeelectron laser facility FLASH would allow one to generate 60 attosecond (FWHM) long x-ray pulses with the peak power at the 100 MW level and a contrast above 98%.

Proposal for Carrier-Envelope-Phase Stable Single-Cycle Attosecond Pulse Generation in the Extreme-Ultraviolet Range

“…The generation of half-cycle 50-as EUV pulses with up to 0.1 mJ energy is predicted by coherent Thomson backscattering from a laser-driven relativistic ultrathin electron layer by irradiating a double-foil target with intense few-cycle laser pulses at oblique incidence [9,10]. Various schemes, such as the longitudinal space charge amplifier [11,12], or two-color enhanced self-amplified spontaneous emission (SASE) [13,14] were proposed for attosecond pulse generation at FELs. However, the realization of these technically challenging schemes has yet to be demonstrated and precise waveform control is difficult.In this Letter we propose a robust method for producing waveform-controlled pulses down to half-cycle durations in the mid-infrared (MIR) to the EUV spectral ranges.…”

longitudinal space charge assisted echo seeding of a free electron laser

“…In the LSC-EEHG with laser spoiler noise suppression concept, a new type of echo-seeding is used in conjunction with the seeded LSCA lasing suppression concept. This idea builds upon the field of beam slicing techniques [8][9][10][11][12] by combining LSCA [12,18,19] physics with Echo Enabled Harmonic Generation (EEHG), also known as echo-seeding [20,21]. Particle tracking simulations in 3D are used to show the performance of LSC-EEHG with noise suppression [22] for 8 nm and 20 nm conditions at the Free-electron LASer in Hamburg.…”

“…The FEL community has pursued methods to improve the temporal coherence properties of the light [1][2][3][4][5][6][7] and to generate shorter, tunable FEL pulses [5][6][7][8][9][10][11][12]. When the temporal coherence of FEL light is determined by the shot noise of an electron beam, as in Self Amplified Spontaneous Emission (SASE), it is poor [13][14][15] but if it is determined by an external seed laser, the FEL light takes on the excellent temporal coherence properties of the external laser in the region which has been seeded.…”

Longitudinal space charge assisted echo seeding of a free-electron laser with laser-spoiler noise suppression

“…Short-wavelength, high-brightness light sources, like free-electron lasers (FELs) driven by particle accelerators, are in demand for experiments studying ultrafast processes in matter. The FEL community has pursued methods to improve the temporal coherence properties of the light [1][2][3][4][5][6][7] and to generate shorter, tunable FEL pulses [5][6][7][8][9][10][11][12]. When the temporal coherence of FEL light is determined by the shot noise of an electron beam, as in self-amplified spontaneous emission (SASE), it is poor [13][14][15], but if it is determined by an external seed laser, the FEL light takes on the excellent temporal coherence properties of the external laser in the region that has been seeded.…”

“…The seeding method described in this paper combines seeded LSCA SASE suppression with a short, echo-seeded pulse of temporally coherent FEL radiation. The idea builds upon the field of beam slicing techniques [8][9][10][11][12] by combining concepts from LSCA [12,18,19] with echo enabled harmonic generation (EEHG), also known as echo-seeding [20,21]. Standard EEHG uses a modulatorchicane-modulator-chicane configuration with two seed lasers to modulate and filament the electron beam in the first stage and to modulate and bunch the beam in the second stage.…”