Measurement of subpicosecond electron pulses

Lihn, Hung‐chi; Kung, Pamela; Settakorn, C.; Wiedemann, Helmut; Bocek, David

doi:10.1103/physreve.53.6413

Cited by 71 publications

(37 citation statements)

References 7 publications

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“…Many instruments have evolved to characterize CTR for longer wavelengths and were considered for extension down to the few-µm bunch regime [14][15][16][17][18][19][20][21].…”

Section: Slac−pub−15692mentioning

confidence: 99%

Coherent-Radiation Spectroscopy of Few-Femtosecond Electron Bunches Using a Middle-Infrared Prism Spectrometer

et al. 2013

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Modern, high-brightness electron beams such as those from plasma wakefield accelerators and free-electron laser linacs continue the drive to ever-shorter bunch durations. In low-charge operation (∼20 pC), bunches shorter than 10 fs are reported at the Linac Coherent Light Source (LCLS). Though suffering from a loss of phase information, spectral diagnostics remain appealing as compact, low-cost bunch duration monitors suitable for deployment in beam dynamics studies and operations instrumentation. Progress in middle-infrared (MIR) imaging has led to the development of a single-shot, MIR prism spectrometer to characterize the corresponding LCLS coherent beam radiation power spectrum for few-femtosecond scale bunch length monitoring. In this letter we report on the spectrometer installation as well as the temporal reconstruction of 3 to 60 fs-long LCLS electron bunch profiles using single-shot coherent transition radiation spectra. 41.60.Dk, 41.75.Ht Generation and characterization of femtosecond duration electron bunches are of paramount importance in high-energy collider, plasma wakefield accelerator (PWFA), and x-ray free-electron laser (FELs) applications. In a PWFA, driven by either a laser or an electron bunch, the duration of the accelerated bunch is intrinsically shorter than the plasma oscillation period which is typically on the order of 100 fs [1]. In x-ray FELs, it is understood that reducing the charge per bunch alleviates internal space charge and other nonlinear, beam-induced forces allowing for a corresponding reduction of the minimum possible duration. For example, when operating with tens of picocoloumb bunch charges the Linac Coherent Light Source (LCLS) [2] is capable of generating electron and x-ray pulses with durations of just a few femtoseconds [3]. Diagnosis of the longitudinal electron distribution is therefore highly desirable for FEL optimization studies and presents a unique challenge to the resolution of existing diagnostics, reaching into the few-fs scale. In this letter we present first results using a newly developed frequency-domain diagnostic with advantages of economy and robustness over direct timedomain diagnostics [4][5][6] for the LCLS. The prism-based spectrometer demonstrated yields novel, single-shot measurements over a wide, middle-infrared (MIR) spectral range previously unexplored in longitudinal beam diagnostics.Frequency-domain bunch length measurements are based on observing the power spectrum of light from an electron bunch undergoing a radiative process, occurring when the beam experiences a change in trajectory or medium [7,8]. In the low-frequency range, where κ ∼ < (2πσ z ) −1 with σ z the electron bunch length and κ the spatial frequency κ ≡ 1/λ, the radiated power has a well-known coherent enhancement that scales with the number of electrons N over the incoherent beam radiation background. In the one-dimensional bunch limit where the transverse electron beam size is much smaller than the transverse coherence length, the coherent spectral density profile c...

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“…Many instruments have evolved to characterize CTR for longer wavelengths and were considered for extension down to the few-µm bunch regime [14][15][16][17][18][19][20][21].…”

Section: Slac−pub−15692mentioning

confidence: 99%

Coherent-Radiation Spectroscopy of Few-Femtosecond Electron Bunches Using a Middle-Infrared Prism Spectrometer

et al. 2013

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“…The total number of photcm radiated is highly enhanced when the observation wavelength is comparable to or greater than the bunch length. The total radiation distribution becomes [9] (1)…”

Section: Coherent Transition Radiation Of Multiple Bunches -mentioning

confidence: 99%

STELLA experiment—microbunch diagnostic

He¹,

Liu²,

Cline³

et al. 1999

AIP Conference Proceedings

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“…As electron beam bunch length getting shorter, the coherent radiation becomes a viable option. Coherent synchrotron radiation [17], transition radiation [18] and diffraction radiation [19] have been used for bunch length measurements. This technique has demonstrated resolution on the order of 100 fs.…”

Section: Fig12mentioning

confidence: 99%

Single-pass high-gain free electron laser electron beam diagnostics

Wang¹

2000

AIP Conference Proceedings

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Consensus reached in the last few years that fourth generation light source will most likely be a X -ray or a UV coherent source based on single-pass high-gain free electron laser (FEL), such as Self Amplified Spontaneous Emission (SASE), or seeded high-gain harmonic -generation (HGHG) free electron lasers. High -gain (> 10 7 ) required for single -pass FEL puts great constrain on the quality of electron beam, and demands detailed distribution information of electron beam in six -dimension. The typical accelerator system for single -pass FEL consists of a photocathode RF gun injection system, a linac and magnetic bunch compressors, and a long undulator. The major challenges in beam diagnostics for single -pass FEL are to characterize the pico-seconds high-brightness electron beam in six -dimension produced by photocathode RF gun injector, and impro ve the stability and reliability of the photocathode RF gun injection system. Characterization of short electron bunch (∼100 fs) produced by the compressors, and co-align the electron beam with FEL radiation inside long undulator are also critical for FEL performance. We will discuss many diagnostic techniques developed at the Brookhaven Accelerator Test Facility (ATF) for the photocathode RF gun injection system, present several techniques for femto-seconds bunch length measurement, especially RF kicker cavity. Tomography technique for both transverse and longitudinal phase space measurements is discussed. Concept of multiple alignment -laser stations is present for beam alignment in the long undulator.

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Measurement of subpicosecond electron pulses

Cited by 71 publications

References 7 publications

Coherent-Radiation Spectroscopy of Few-Femtosecond Electron Bunches Using a Middle-Infrared Prism Spectrometer

Coherent-Radiation Spectroscopy of Few-Femtosecond Electron Bunches Using a Middle-Infrared Prism Spectrometer

STELLA experiment—microbunch diagnostic

Single-pass high-gain free electron laser electron beam diagnostics

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