Bunch length measurement of picosecond electron beams from a photoinjector using coherent transition radiation

Murokh, A.; Rosenzweig, James; Hogan, Mark; Suk, Hyyong; Travish, G.; Happek, U.

doi:10.1016/s0168-9002(98)00177-6

Cited by 75 publications

(53 citation statements)

References 5 publications

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“…Although the wakefield of a relativistic bunch follows the bunch shape, the fields radiated by the foil are filtered by the finite beampipe and window, and so lose long wavelengths. To compensate the spectrum for this loss, we model the attenuation of the field as a Gaussian highpass filter, 22 1−exp(−f 2 /f 0 2 ), which leads to negative lobes on either side of the main peak of the interferogram. With data from a highly compressed beam, which has a nearly Gaussian profile, we fit the center of the autocorrelation in the time domain (Figure 8(a)) with a Gaussian beam and filter to find the filter constant f 0 .…”

Section: Measurementsmentioning

confidence: 99%

Intense terahertz pulses from SLAC electron beams using coherent transition radiation

Fisher

Goodfellow

et al. 2013

Review of Scientific Instruments

145

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SLAC has two electron accelerators, the Linac Coherent Light Source (LCLS) and the Facility for Advanced Accelerator Experimental Tests (FACET), providing high-charge, high-peak-current, femtosecond electron bunches. These characteristics are ideal for generating intense broadband terahertz (THz) pulses via coherent transition radiation. For LCLS and FACET respectively, the THz pulse duration is typically 20 and 80 fs RMS and can be tuned via the electron bunch duration; emission spectra span 3-30 THz and 0.5 THz-5 THz; and the energy in a quasi-half-cycle THz pulse is 0.2 and 0.6 mJ. The peak electric field at a THz focus has reached 4.4 GV/m (0.44 V/Å) at LCLS. This paper presents measurements of the terahertz pulses and preliminary observations of nonlinear materials response.

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Section: Measurementsmentioning

confidence: 99%

Intense terahertz pulses from SLAC electron beams using coherent transition radiation

Fisher

Goodfellow

et al. 2013

Review of Scientific Instruments

145

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“…For single shot electron diffraction application a charge of 1 pC is typically required [5]. It should be noted that the pC level charge is already two orders smaller than conventional CTR based measurement [25,37].…”

Section: Requirement On the Charge Of Bunchmentioning

confidence: 99%

“…In the laser plasma acceleration field [2,22], as well as in the FEL community [1,23], spectral methods based on bunch-generated coherent transition radiation (CTR) are the most competitive candidates for the temporal characterization of bunch lengths shorter than 10 fs. These measurements are conventionally performed with scanning interferometer and yield the autocorrelation of the CTR signal [24,25]. Besides the use of an interferometer, single shot CTR spectrum retrieval method has been developed by Wesch et al, using consecutive dispersion gratings and multichannel detector [26].…”

Section: Introductionmentioning

confidence: 99%

Generation and measurement of velocity bunched ultrashort bunch of pC charge

Tang

et al. 2015

Phys. Rev. ST Accel. Beams

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In this paper, we discuss the velocity compression in a short rf linac of an electron bunch from a rf photoinjector operated in the blowout regime. Particle tracking simulations shows that with a beam charge of 2 pC an ultrashort bunch duration of 16 fs can be obtained at a tight longitudinal focus downstream of the linac. A simplified coherent transition radiation (CTR) spectrum method is developed to enable the measurement of ultrashort (sub-50 fs) bunches at low bunch energy (5 MeV) and low bunch charges (<10 pC). In this method, the ratio of the radiation energy selected by two narrow bandwidth filters is used to estimate the bunch length. The contribution to the coherent form factor of the large transverse size of the bunch suppresses the radiation signal significantly and is included in the analysis. The experiment was performed at the UCLA Pegasus photoinjector laboratory. The measurement results show bunches of sub-40 fs with 2 pC of charge well consistent with the simulation using actual experimental conditions. These results open the way to the generation of ultrashort bunches with time-duration below 10 fs once some of the limitations of the setup (rf phase jitter, amplitude instability and low field in the gun limited by breakdown) are corrected.

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“…CTR was used by several other groups to measure the longitudinal charge density of electron bunches [9][10][11][12]. A major problem that all groups encountered is that the intensity of the coherent transition radiation [Eq.…”

Section: Introductionmentioning

confidence: 99%

“…Another approach is to avoid the use of the Kramers-Kroning method (which requires the intensity for all frequencies) by assuming that bunches have a predefined shape (Gaussian or superposition of two Gaussians), parametrized by some free parameters. These free parameters can be extracted from the measured intensity spectra, also corrected to account for the depletion at low frequencies [11,12].…”

Section: Introductionmentioning

confidence: 99%

Longitudinal electron bunch diagnostics using coherent transition radiation

Mihalcea

Bohn

Happek

et al. 2006

Phys. Rev. ST Accel. Beams

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The longitudinal charge distribution of electron bunches in the Fermilab/NICADD photoinjector was determined using the coherent transition radiation produced by electrons passing through a thin metallic foil. The autocorrelation of the transition radiation signal was measured with a Michelson-type interferometer. The response function of the interferometer was determined from measured and simulated intensity spectra for low electron bunch charge and maximum longitudinal compression. Both pyroelectric and Golay detectors were used for these measurements. A Kramers-Kronig technique was used to determine longitudinal charge distribution. Measurements were performed for electron bunch lengths in the range from 0.3 to 2 ps (rms). To test the accuracy of this interferometric method, the longitudinal charge distribution was measured for double-peaked electron bunches with known distance between the two pulses. The agreement between measured bunch length and simulation is within 30%.

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Bunch length measurement of picosecond electron beams from a photoinjector using coherent transition radiation

Cited by 75 publications

References 5 publications

Intense terahertz pulses from SLAC electron beams using coherent transition radiation

Intense terahertz pulses from SLAC electron beams using coherent transition radiation

Generation and measurement of velocity bunched ultrashort bunch of pC charge

Longitudinal electron bunch diagnostics using coherent transition radiation

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