Implementation and modeling of a femtosecond laser-activated streak camera

Zandi, Omid; Wilkin, Kyle; Centurion, Martin

doi:10.1063/1.4985008

Cited by 5 publications

(2 citation statements)

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“…The performance of the streak camera was characterized in a previous publication. 45 Briefly, the streaking device consists of a charged parallel plate capacitor in parallel to a GaAs photo-switch. Once a laser pulse excites the switch, the capacitor will be short circuited and the electric field across the capacitor starts a damped oscillation.…”

Section: Measurement Of the Electron Pulse Durationmentioning

confidence: 99%

High current table-top setup for femtosecond gas electron diffraction

Zandi

Wilkin

Xiong

et al. 2017

Structural Dynamics

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We have constructed an experimental setup for gas phase electron diffraction with femtosecond resolution and a high average beam current. While gas electron diffraction has been successful at determining molecular structures, it has been a challenge to reach femtosecond resolution while maintaining sufficient beam current to retrieve structures with high spatial resolution. The main challenges are the Coulomb force that leads to broadening of the electron pulses and the temporal blurring that results from the velocity mismatch between the laser and electron pulses as they traverse the sample. We present here a device that uses pulse compression to overcome the Coulomb broadening and deliver femtosecond electron pulses on a gas target. The velocity mismatch can be compensated using laser pulses with a tilted intensity front to excite the sample. The temporal resolution of the setup was determined with a streak camera to be better than 400 fs for pulses with up to half a million electrons and a kinetic energy of 90 keV. The high charge per pulse, combined with a repetition rate of 5 kHz, results in an average beam current that is between one and two orders of magnitude higher than previously demonstrated.

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Section: Measurement Of the Electron Pulse Durationmentioning

confidence: 99%

High current table-top setup for femtosecond gas electron diffraction

Zandi

Wilkin

Xiong

et al. 2017

Structural Dynamics

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“…Coulomb explosion is a ubiquitous phenomenon resulting from the intense self-electric field of a charge distribution. The experimental and theoretical study of Coulomb explosion as a collective behavior of highdensity charge distributions has been of interest in several different disciplines, including laser ablation [1][2][3], photoemission in electron sources and charged-particle optics [4][5][6][7][8], in streak cameras and microwave tubes [9][10][11], cold ion sources [12,13], plasma physics [14][15][16], plasma wakefield accelerators [17,18], chemical reactions [19], and space-charge imaging of molecules [20][21][22]. The characteristics of the charge distribution, i.e., its shape, uniformity, and initial velocity distribution, and the theoretical approximations necessary to describe its dynamics, depend on the specific application.…”

Section: Introductionmentioning

confidence: 99%

General formulation of Coulomb explosion dynamics of highly symmetric charge distributions

Zandi¹,

Veen²

2022

J. Phys. Commun.

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We present a theoretical approach to study the dynamics of spherical, cylindrical and ellipsoidal charge distributions under their self-Coulomb field and a stochastic force due to collisions and random motions of charged particles. The approach is based on finding the current density of the charge distribution from the charge-current continuity equation and determining the drift velocities of the particles. The latter can be used either to derive the Lagrangian of the system, or to write Newton’s equation of motion with the Lorentz force. We develop a kinetic theory to include the stochastic force due to random motions of electrons in our model. To demonstrate the efficacy of our method, we apply it to various charge distributions and compare our results to N-body simulations. We show that our method reproduces the well-known emittance term in the envelope equation of uniform spherical and cylindrical charge distributions with correct coefficients. We use our model for the gravitational collapse of an ideal gas as well as the cyclotron dynamics of a cylindrical charge distribution in a uniform magnetic field and propose a method to measure the emittance of electron beams.

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