Predominant contribution of direct laser acceleration to high-energy electron spectra in a low-density self-modulated laser wakefield accelerator

King, Paul M.; Miller, Kyle; Lemos, N.; Shaw, Jessica; Kraus, Brian; Thibodeau, Matthew; Hegelich, B. M.; Hinojosa, J.; Michel, P.; Joshi, C.; Marsh, Ken; Mori, W. B.; Pak, A.; Thomas, Alexander; Albert, F.

doi:10.1103/physrevaccelbeams.24.011302

Cited by 13 publications

(9 citation statements)

References 36 publications

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“…The dynamics responsible for accelerating high- Z electrons to high energies is identified by first dividing each spectrum in Fig. 4B into two electron populations, labeled “L” for LWFA and “D” for DLA, according to whether most of the integrated work was performed on the electrons is parallel or transverse to the laser direction ( 18 , 38 ); see further details in Materials and Methods. Within each of these subpopulations, the spectra are color-coded according to the ionization level from which they emerged.…”

Section: Resultsmentioning

confidence: 99%

“…The relative contributions of DLA and LWFA to the acceleration of each simulated electron are quantified by considering the integrated work performed on it in the longitudinal and transverse directions ( 18 , 38 )W∥=−∫0t‍2eE∥P∥false(italicmcfalse)2dt,W⊥=−∫0t‍2etrueE→⊥·trueP→⊥false(italicmcfalse)2dtwhere E ∥ P ∥ and trueE→⊥·trueP→⊥ are the products of the energy and momentum components in the directions parallel and transverse to the laser direction, respectively. This distinction is a good measure for the dominant acceleration mechanism because, while, for LWFA, the acceleration occurs via the forward-pushing field gradients in the plasma wakes, for DLA, electrons are gaining energy through transverse oscillations, which are later directed forward through Jtrue→×Btrue→ forces.…”

Section: Methodsmentioning

confidence: 99%

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Undepleted direct laser acceleration

Cohen,

Meir,

Tangtartharakul

et al. 2024

Sci. Adv.

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Intense lasers enable generating high-energy particle beams in university-scale laboratories. With the direct laser acceleration (DLA) method, the leading part of the laser pulse ionizes the target material and forms a positively charged ion plasma channel into which electrons are injected and accelerated. The high energy conversion efficiency of DLA makes it ideal for generating large numbers of photonuclear reactions. In this work, we reveal that, for efficient DLA to prevail, a target material of sufficiently high atomic number is required to maintain the injection of ionization electrons at the peak intensity of the pulse when the DLA channel is already formed. We demonstrate experimentally and numerically that, when the atomic number is too low, the target is depleted of its ionization electrons prematurely. Applying this understanding to multi-petawatt laser experiments is expected to result in increased neutron yields, a perquisite for a wide range of research and applications.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Undepleted direct laser acceleration

Cohen,

Meir,

Tangtartharakul

et al. 2024

Sci. Adv.

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“…Depending on laser and plasma parameters, betatron radiation can be generated in the process of the laser wakefield acceleration (LWFA) [15][16][17], self-modulated LWFA (SM-LWFA) [18][19][20][21], direct laser acceleration (DLA) [22,23] or a hybrid regime [5,24].…”

mentioning

confidence: 99%

“…At the same time, the nature of SM-LWFA based on instabilities, leads to a rather poor reproducibility of results [31]. It has also been shown that SM-LWFA is the main mechanism for accelerating electrons up to energies of ~40 MeV, while for higher energies direct laser acceleration (DLA) dominates [24]. The major role of DLA in interaction of the Vulcan ultra-intense laser pulses with a normalized vector potential a0 > 10 with high density gas-target was also discussed in [32].…”

mentioning

confidence: 99%

High-brightness betatron emission from the interaction of a sub picosecond laser pulse with pre-ionized low-density polymer foam for ICF research

Gyrdymov,

Cikhardt,

Tavana

et al. 2024

Preprint

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Direct laser acceleration (DLA) of electrons in plasmas of near-critical density (NCD) is a very advancing platform for high-energy PW-class lasers of moderate relativistic intensity supporting Inertial Confinement Fusion research. Experiments conducted at the PHELIX sub-PW Nd:glass laser demonstrated application-promising characteristics of DLA-based radiation and particle sources, such as ultra-high number, high directionality and high conversion efficiency. In this context, the bright synchrotron-like (betatron) radiation of DLA electrons, which arises from the interaction of a sub-ps PHELIX laser pulse with an intensity of 1019 W/cm2 with pre-ionized low-density polymer foam, was studied. The experimental results show that the betatron radiation produced by DLA electrons in NCD plasma is well directed with a half-angle of 100-200 mrad, yielding (3.4 ± 0.4)·1010 photons/keV/sr at 10 keV photon energy. The photon fluence in the energy range of 10–30 keV reaches (2.2 ± 0.3)·1011 photons/sr and the brilliance at 10 keV approaches ~2·1020 photons/s/mm2/mrad2/(0.1% BW), which agrees well with the particle-in-cell simulations. These results pave the way for innovative applications of the DLA regime using low-density pre-ionized foams in high-energy density research.

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“…However, current high-efficiency laser technologies cannot generate a suitable second wavelength with the required high average power. Plasma waves can also be driven via self-modulation of long laser pulses [50,51], but this relies on stochastic, and highly nonlinear, processes which would make controlled injection and acceleration difficult.…”

mentioning

confidence: 99%

Gev-Scale Accelerators Driven by Plasma-Modulated Pulses from Kilohertz Lasers

2021

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We describe a new approach for driving GeV-scale plasma accelerators with long laser pulses. We show that the temporal phase of a long, high-energy driving laser pulse can be modulated periodically by co-propagating it with a low-amplitude plasma wave driven by a short, low-energy seed pulse. Compression of the modulated driver by a dispersive optic generates a train of short pulses suitable for resonantly driving a plasma accelerator. Modulation of the driver occurs via well-controlled linear processes, as confirmed by good agreement between particle-in-cell (PIC) simulations and an analytic model. PIC simulations demonstrate that a 1.7 J, 1 ps driver and a 140 mJ, 40 fs seed pulse can accelerate electrons to energies of 0.65 GeV in a plasma channel with an axial density of 2.5 × 10 17 cm −3 . This work opens a route to high-repetition-rate, GeV-scale plasma accelerators driven by thin-disk lasers, which can provide joule-scale, picosecond-duration laser pulses at multikilohertz repetition rates and high wall-plug efficiencies.

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Predominant contribution of direct laser acceleration to high-energy electron spectra in a low-density self-modulated laser wakefield accelerator

Cited by 13 publications

References 36 publications

Undepleted direct laser acceleration

Undepleted direct laser acceleration

High-brightness betatron emission from the interaction of a sub picosecond laser pulse with pre-ionized low-density polymer foam for ICF research

Gev-Scale Accelerators Driven by Plasma-Modulated Pulses from Kilohertz Lasers

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