Segmented terahertz electron accelerator and manipulator (STEAM)

Zhang, Dongfang; Fallahi, Arya; Hemmer, Michaël; Wu, Xiaojun; Fakhari, Moein; Hua, Yi; Çankaya, Hüseyin; Calendron, Anne-Laure; Zapata, Luis E.; Matlis, Nicholas H.; Kärtner, Franz X.

doi:10.1038/s41566-018-0138-z

Cited by 277 publications

(169 citation statements)

References 41 publications

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“…The drift distance is determined by the shortest achievable temporal focal length and the energy resolution scales with the THz power at the streaking element. Electron beam modulation has been demonstrated with THz peak fields exceeding 10 7 V/m, 45 about 20 times larger than in our experiment. With such sources, our THz-ToF could reach a length of merely centimeters.…”

Section: Discussioncontrasting

confidence: 46%

Electron energy analysis by phase-space shaping with THz field cycles

Ehberger

Kealhofer

Baum

2018

Structural Dynamics

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Time-resolved electron energy analysis and loss spectroscopy can reveal a wealth of information about material properties and dynamical light-matter interactions. Here, we report an all-optical concept for measuring energy spectra of femtosecond electron pulses with sub-eV resolution. Laser-generated terahertz radiation is used to measure arrival time differences within electron pulses with few-femtosecond precision. Controlled dispersion and subsequent compression of the electron pulses provide almost any desired compromise of energy resolution, signal strength, and time resolution. A proof-of-concept experiment on aluminum reveals an energy resolution of <3.5 eV (rms) at 70-keV after a drift distance of only 0.5 m. Simulations of a two-stage scheme reveal that pre-stretched pulses can be used to achieve <10 meV resolution, independent of the source's initial energy spread and limited only by the achievable THz field strength and measuring time.

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Section: Discussioncontrasting

confidence: 46%

Electron energy analysis by phase-space shaping with THz field cycles

Ehberger

Kealhofer

Baum

2018

Structural Dynamics

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“…[189][190][191] Electron acceleration, undulation, deflection, and spatial as well as temporal focusing with THz fields has been proposed. [23] In segmented THz electron accelerator and manipulator (STEAM) structures (Figure 27a), [194] acceleration with 70 keV energy gain, [195] bunch compression to 100 fs, [194,195] as well as deflection and focusing have been achieved. [193] In the first proof-of-principle experiment of THz-driven electron acceleration, 7 keV energy gain was demonstrated in a mm-sized dielectric-loaded cylindrical metallic waveguide, driven by 10 µJ THz pulses.…”

Section: Free Charged Particlesmentioning

confidence: 99%

Laser‐Driven Strong‐Field Terahertz Sources

Fülöp

Tzortzakis

Kampfrath

2019

Advanced Optical Materials

270

147

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reason for this interest relies on the fact that THz radiation can couple resonantly to numerous fundamental motions of ions, electrons, and electron spins in all phases of matter. For example, in solids, the THz range overlaps with the frequency of lattice vibrations (phonons), the collision rates of conduction electrons, the binding energy of bound electron-hole pairs (excitons), and the precession frequency of spin waves (magnons). Consequently, THz radiation, both continuous-wave and pulsed, has been used for characterization of and gaining insight into elementary processes in complex materials. The majority of these studies used relatively weak THz fields and, thus, probed the linear response of the material, without inducing notable material modifications.Only recently, however, completely new avenues in THz science were opened up by triggering nonlinear THz responses of materials. [3][4][5][6][7][8][9][10][11][12][13] Instead of using weak fields to primarily observe selected THz modes such as phonons or magnons, strong fields allow one to actively drive them to unprecedentedly large amplitudes, potentially thereby resulting in novel states of matter. [6,8,11] For example, simulations suggest that exciting matter with intense THz transients may lead to massive modifications of electrically [14] or magnetically [15] ordered domains and enable the acceleration of free ions to ≈1 MeV, [16] and postacceleration to 50-100 MeV energies. [17] Remarkable experimental results such as switching of magnetic order, [18,19] parametric amplification of optical phonons, [20] novel insights into spin-lattice coupling, [21,22] and acceleration of free electrons in a THz linear accelerator [23] were achieved only recently. This progress has been made possible by the development of laser-driven table-top THz sources routinely providing pulses with unprecedented energies and peak electric and magnetic field strengths throughout the entire THz spectral range. Different laser-based THz pulse generation techniques can be used to access different parts of the spectral range extending from 0.1 to 10 THz. Some of the recently developed technologies enable the generation of radiation with even larger bandwidth or tuning range up to 100 THz and beyond, which lead to an extension of what is called the THz spectral range. An overview of the approximate spectral coverage and the achieved highest pulse energies and peak electric-field strengths of various laserdriven technologies is given in Figure 1. ScopeIn this work, the basic principles of femtosecond-laser-driven intense pulsed THz sources and their recent development are reviewed. These sources are capable of delivering peak electric field strengths on the MV cm −1 scale. Corresponding typical THz pulse energies are on the µJ-to-mJ level, depending on A review on the recent development of intense laser-driven terahertz (THz) sources is provided here. The technologies discussed include various types of sources based on optical rectification (OR), spintronic emitters, and laserfilame...

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“…If the pulses are delayed with respect to each other by half a THz wavelength, the electric fields cancel in the center of the device and the transvers magnetic fields add, which leads to a transvers deflection of the electron bunch. This operation mode can be used for streaking of the electron bunch to measure its duration [12]. The deflection strength of about 140 µrad/fs allows for sub-10 femtosecond resolution.…”

Section: Thz Guns and Accelerationmentioning

confidence: 99%

THz Driven Accelerators and X-ray Sources

Kärtner

2018

Conference on Lasers and Electro-Optics

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Approaches towards a linear THz accelerator technology are discussed. Theoretical and first experimental results on laser based high energy THz generation, guns, accelerators as well as compact X-ray sources based on these devices are presented. IntroductionToday, high brightness and highly relativistic electron beams are generated by circular or linear accelerators (LINAC) typically operating with 1-3 GHz accelerating frequencies and approaches towards X-band frequencies in the 10 GHz range are maturing. The achievable accelerating gradients are limited by field emission from cavity walls influenced by pulsed heating to several tens of MV/m in the case of low frequencies and up to 100 MV/m in the case of X-band frequencies. Short electron bunches are typically created by photoemission from the cathode in the presence of a strongly accelerating field followed by bunch compression. Low charge bunches, 1-10 pC, may be compressed to durations down to 3 -10 µm (or 10 -30 fs in pulse duration). At a given accelerating field strength and RF frequency, compression is limited by space charge. With higher operating frequency, higher gradients in the accelerating electric field arise which enhances velocity bunching and leads to the generation of shorter electron bunches. These short electron bunches can be used for ultrafast electron diffraction or intense X-ray production. Choosing an operating frequency of the accelerator in the THz range, i.e. here 0.1 -0.5 THz and using multi-cycle to single-cycle pulses, accelerating fields in the 0.3 to 1 GV/m range are sustainable and bunch compression to the sub-femtosecond level of significant charge on the order of ~1 pC becomes possible. To drive electron guns and accelerators high-energy single-cycle and multi-cylce THz pulses in the mJ and tens of mJ range, respectively, are necessary. Here, we discuss approaches towards this goal and results achieved sofar.

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Segmented terahertz electron accelerator and manipulator (STEAM)

Cited by 277 publications

References 41 publications

Electron energy analysis by phase-space shaping with THz field cycles

Electron energy analysis by phase-space shaping with THz field cycles

Laser‐Driven Strong‐Field Terahertz Sources

THz Driven Accelerators and X-ray Sources

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