Observations of low-aberration plasma lens focusing of relativistic electron beams at the underdense threshold

Thompson, M. C.; Badakov, H.; Rosenzweig, J.; Travish, G.; Barov, N.; Piot, P.; Fliller, R.; Kazakevich, Grigory; Santucci, J.; Li, J.; Tikhoplav, R.

doi:10.1063/1.3457924

Cited by 16 publications

(10 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This effect was studied theoretically [15][16][17][18] and experimentally [19][20][21][22][23][24], in the context of conventional accelerators. However, in a plasma lens, there is always a finite length at the bunch head over which the focusing is very nonuniform [18,21,24] (this effect typically gives rise to head erosion). This is a major drawback for the short LWFA bunches, because this finite length can be comparable to the length of the bunch itself [25].…”

Section: Introductionmentioning

confidence: 99%

Laser-plasma lens for laser-wakefield accelerators

Lehe

Thaury

Guillaume

et al. 2014

Phys. Rev. ST Accel. Beams

View full text Add to dashboard Cite

International audienceThanks to their compactness and unique properties, laser-wakefield accelerators are currently considered for several innovative applications. However, many of these applications—and especially those that require beam transport—are hindered by the large divergence of laser-accelerated beams. Here we propose a collimating concept that relies on the strong radial electric field of the laser-wakefield to reduce this divergence. This concept utilizes an additional gas jet, placed after the laser-wakefield accelerator. When the laser pulse propagates through this additional gas jet, it drives a wakefield which can refocus the trailing electron bunch. Particle-in-cell simulations demonstrate that this approach can reduce the divergence by at least a factor of 3 for realistic electron bunches

show abstract

Section: Introductionmentioning

confidence: 99%

Laser-plasma lens for laser-wakefield accelerators

Lehe

Thaury

Guillaume

et al. 2014

Phys. Rev. ST Accel. Beams

View full text Add to dashboard Cite

show abstract

“…To our knowledge the beam divergence presented here is the smallest published to date for LWFA beams and can be attributed to the longer density downramp of our gas cell as opposed to commonly used supersonic gas jets. To reduce the source divergence further, a separate density peak (in our case $10 15 cm À3 ) could be incorporated slightly downstream of the main downramp and be used to focus the beam similarly to work being done on plasma lenses [31]. Provided the laser pulse still contains enough energy to create an ion channel, this even promises to focus the entire bunch as opposed to only the rear part for a purely beamdriven plasma lens.…”

mentioning

confidence: 97%

Ultralow emittance electron beams from a laser-wakefield accelerator

Weingartner

Raith

Popp

et al. 2012

Phys. Rev. ST Accel. Beams

144

114

View full text Add to dashboard Cite

Using quadrupole scan measurements we show laser-wakefield accelerated electrons to have a normalized transverse emittance of 0:21 þ0:01 À0:02 mm mrad at 245 MeV. We demonstrate a multishot and a single-shot method, the mean emittance values for both methods agree well. A simple model of the beam dynamics in the plasma density downramp at the accelerator exit matches the source size and divergence values inferred from the measurement. In the energy range of 245 to 300 MeV the normalized emittance remains constant.Laser-wakefield acceleration (LWFA) [1,2] can deliver ultrarelativistic electron beams in a compact setup with unique features [3][4][5][6]. It is receiving particular attention as a source or driver for ultrashort x-ray beams [7,8] and for its potential for realizing a tabletop free-electron laser (FEL) [9]. The electron bunch duration has recently been measured to be only a few femtoseconds long [10,11] which results in peak beam currents on the order of kiloamperes. An essential parameter for the performance of x-ray sources, FELs, or linear colliders is the transverse electron beam emittance. Previous emittance measurements of LWFA electron beams have used the pepperpot method [12][13][14] giving normalized emittances of $2:2 mm mrad with single shots down to the resolution limit of 1:1 mm mrad. As these measurements are not spectrally resolved, they rely on a low energy spread to give a meaningful normalized emittance. For LWFA beams which fluctuate in energy and energy spread, a simultaneous measurement of the spectrum is required. This technique is also limited to electron energies that can be sufficiently scattered by the pepper-pot mask; to date, measurements of a 508 MeV beam have been carried out [15]. Experiments characterizing the betatron radiation emitted by the electron beam while it is in the plasma suggest the beam size there to be & 1 m [16,17], which in combination with a divergence measurement give an estimated emittance of <0:5 mm mrad [18]. However, inferring the emittance from the electron beam size in the plasma and its downstream divergence in the vacuum can be unreliable as this neglects the plasma-vacuum density transition at the accelerator exit; here the decreasing strength of the plasma focusing forces result in an increase in beam size and decrease in divergence [13]. This publication reports on direct measurements of the emittance of LWFA electrons that are both energy resolved and that include the beam transport of the density downramp at the accelerator exit. This is achieved by analyzing their beam size around a focus using a quadrupole lens scan method [19].The transverse phase space of an electron beam is often specified using the Twiss parameters , , , and the natural emittance ". These parameters describe the volume and orientation of the particle distribution in phase space. The beam size at a particular position ðs 1 Þ is related to the Twiss parameters at s 0 by [20] ðs 1 Þ 2 ¼ M 2 11 ðs 0 Þ À2M 11 M 12 ðs 0 Þþ M 2 12 ðs 0 Þ: (1)Here M ij refers to the ij eleme...

show abstract

“…1(b), and is much weaker for the shorter focal length of the active plasma lens (red curve). Note that plasma-wakefield lenses, where focusing wakefields are driven by either the electron beam itself [27][28][29][30] or a laser pulse [31,32], have been considered for their ultra-strong focusing fields, even approaching 1 T/µm [28]. However, their applicability is challenging since the focusing force has an intrinsic longitudinal variation (electrons in the head of the beam experience a different lens strength than the electrons in the tail), and tunability is limited since electron beam parameters (charge, current profile, size) strongly effect the focusing forces and lens aberrations.…”

mentioning

confidence: 99%

Active Plasma Lensing for Relativistic Laser-Plasma-Accelerated Electron Beams

et al. 2015

View full text Add to dashboard Cite

Compact, tunable, radially symmetric focusing of electrons is critical to laser-plasma accelerator (LPA) applications. Experiments are presented demonstrating the use of a discharge-capillary active plasma lens to focus 100-MeV-level LPA beams. The lens can provide tunable field gradients in excess of 3000 T/m, enabling cm-scale focal lengths for GeV-level beam energies and allowing LPA-based electron beams and light sources to maintain their compact footprint. For a range of lens strengths, excellent agreement with simulation was obtained.

show abstract

Observations of low-aberration plasma lens focusing of relativistic electron beams at the underdense threshold

Cited by 16 publications

References 33 publications

Laser-plasma lens for laser-wakefield accelerators

Laser-plasma lens for laser-wakefield accelerators

Ultralow emittance electron beams from a laser-wakefield accelerator

Active Plasma Lensing for Relativistic Laser-Plasma-Accelerated Electron Beams

Contact Info

Product

Resources

About