Towards Attosecond High-Energy Electron Bunches: Controlling Self-Injection in Laser-Wakefield Accelerators Through Plasma-Density Modulation

Tooley, Matthew P.; Ersfeld, Bernhard; Yoffe, Samuel R.; Noble, Adam; Brunetti, E.; Sheng, Z. M.; Islam, M. R.; Jaroszynski, D. A.

doi:10.1103/physrevlett.119.044801

Cited by 59 publications

(71 citation statements)

References 34 publications

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“…An outstanding issue of the LWFA is how to control the injection process, while optimizing the quality of the electron beam produced. In addition to the usual self-injection in the blow-out regime [3,4], injection can also be controlled using additional laser pulses [5][6][7], plasma density transitions [8][9][10][11], external magnetic fields [12][13][14], etc. Recently, controlled ionization injection has also been proposed [15][16][17][18].…”

Section: Introductionmentioning

confidence: 99%

Ionization injection in a laser wakefield accelerator subject to a transverse magnetic field

et al. 2018

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The effect of an external transverse magnetic field on ionization injection of electrons in a laser wakefield accelerator (LWFA) is investigated by theoretical analysis and particle-in-cell simulations. On application of a few tens of Tesla magnetic field, both the electron trapping condition and the wakefield structure changes significantly such that injection occurs over a shorter distance and at an enhanced rate. Furthermore, beam loading is compensated for, as a result of the intrinsic trapezoidal-shaped longitudinal charge density profile of injected electrons. The nonlinear ionization injection and consequent compensation of beam loading lead to a reduction in the energy spread and an enhancement of both the charge and final peak energy of the electron beam from a LWFA immersed in the magnetic field.

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Section: Introductionmentioning

confidence: 99%

Ionization injection in a laser wakefield accelerator subject to a transverse magnetic field

et al. 2018

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“…Beams with an emittance of 1 π mm mrad 17 , energies of 80-300 MeV 1,2,4,11 , and percent level energy spreads 2,4,18 , low divergences (0.5-2 mrad) 18 , peak currents >1 kA and fs bunch duration 5 have been measured on the ALPHA-X beamline ( Figure 2). Theoretical studies ( Figure 1) show that attosecond bunches can be produced by perturbing the plasma density to briefly trigger injection 6 .…”

Section: Lwfa Experimentsmentioning

confidence: 99%

“…Relativistic plasma wakes are produced by the ponderomotive force of intense laser pulses in plasma, which set in motion electron oscillations at the plasma frequency to create tens-of-micron size accelerating and radiating structures. We explore how high-quality [1][2][3][4] , femtosecond 5 to attosecond 6 duration, 1-10 kA peak current electron bunches can be accelerated to 0.1-10 GeV energies in millimetres to centimetres by a laser wakefield accelerator (LWFA) driven by a terawatt laser 1,7 . We also show that the un-trapped sheath electrons can lead to unprecedented 10s of nC bunches with energies of 1-5 MeV 8,9 , which can be transformed into THz radiation with high efficiency 9 , or used directly in imaging, radiation damage and pulsed radiolysis applications.…”

Section: Introductionmentioning

confidence: 99%

Compact radiation sources based on laser-driven plasma waves

Jaroszynski

Amnania

Aniculaesei

et al. 2019

XXII International Symposium on High Power Laser Systems and Applications

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Here we explore ways of transforming laser radiation into incoherent and coherent electromagnetic radiation using laserdriven plasma waves. We present several examples based on the laser wakefield accelerator (LWFA) and show that the electron beam and radiation from the LWFA has several unique characteristics compared with conventional devices. We show that the energy spread can be much smaller than 1% at 130-150 MeV. This makes LWFAs useful tools for scientists undertaking time resolved probing of matter subject to stimuli. They also make excellent imaging tools. We present experimental evidence that ultra-short XUV pulses, as short as 30 fs, are produced directly from an undulator driven by a LWFA, due to the electron bunches having a duration of a few femtoseconds. By extending the electron energy to 1 GeV, and for 1-2 fs duration pulses of 2 nm radiation peak powers of several MW per pC can be produced. The increased charge at higher electron energies will increase the peak power to GW levels, making the LWFA driven synchrotron an extremely useful source with a spectral range extending into the water window. With the reduction in size afforded by using LWFA driven radiation sources, and with the predicted advances in laser stability and repletion rate, ultra-short pulse radiation sources should become more affordable and widely used, which could change the way science is done.

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“…2 There are several ways for electrons to be injected into the bubble. Tooley et al 8 proposed a short persistence down-ramp injection scheme 9 to briefly inject sub-fs electron bunches. Downramp injection occurs when the velocity of the back of the bubble decreases rapidly, which can be achieved by suddenly reducing the plasma density or when the laser intensity increases.…”

Section: Introductionmentioning

confidence: 99%

Plasma density shaping for attosecond electron bunch generation

Kornaszewski

Spesyvtsev

Shahzad

et al. 2019

Relativistic Plasma Waves and Particle Beams as Coherent and Incoherent Radiation Sources III

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High energy attosecond electron bunches from the laser-plasma wakefield accelerator (LWFA) are potentially useful sources of ultra-short duration X-rays pulses, which can be used for ultrafast imaging of electron motion in biological and physical systems. Electron injection in the LWFA depends on the plasma density and gradient, and the laser intensity. Recent research has shown that injection of attosecond electron bunches is possible using a short plasma density ramp. For controlled injection it is necessary to keep both the laser intensity and background plasma density constant, but set to just below the threshold for injection. This ensures that injection is only triggered by an imposed density perturbation; the peak density should also not exceed the threshold for injection. A density gradient that only persists over a short range can lead to the injection of femtosecond duration bunches, which are then Lorentz contracted to attoseconds on injection. We consider an example of a sin 2 shaped modulation where the gradient varies until the downward slope exceeds the threshold for injection and then reduces subsequently to prevent any further injection. The persistence above the threshold determines the injected bunch length, which can be varied. We consider several designs of plasma media including density perturbations formed by shaped Laval nozzles and present an experimental and theoretical study of the modulated media suitable for producing attosecond-duration electron bunches.

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Towards Attosecond High-Energy Electron Bunches: Controlling Self-Injection in Laser-Wakefield Accelerators Through Plasma-Density Modulation

Cited by 59 publications

References 34 publications

Ionization injection in a laser wakefield accelerator subject to a transverse magnetic field

Ionization injection in a laser wakefield accelerator subject to a transverse magnetic field

Compact radiation sources based on laser-driven plasma waves

Plasma density shaping for attosecond electron bunch generation

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