Backward-propagating MeV electrons from 1018 W/cm2 laser interactions with water

Morrison, John T.; Chowdhury, Enam; Frische, Kyle; Feister, Scott; Ovchinńikov, V. M.; Nees, J.; Orban, Chris; Freeman, R. R.; Roquemore, W. M.

doi:10.1063/1.4916493

Cited by 18 publications

(35 citation statements)

References 34 publications

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“…The experimental setup is shown in figure 1, where a dual multi-pass amplifier Ti:Sapphire kHz laser system (KMLabs Red Dragon system, heavily modified for energy, mode and contrast improvements) delivers up to 11 mJ pulses at 780 nm with 40fs pulse duration (FWHM) into a vacuum target chamber [39][40][41] where it can be focused onto the liquid sheet target. In the experiment described here, the laser system delivered 8mJ pulses into the target chamber.…”

Section: Methodsmentioning

confidence: 99%

MeV proton acceleration at kHz repetition rate from ultra-intense laser liquid interaction

et al. 2018

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We regret overlooking two important citations relevant to the current work, and wish to add these [1, 2]. We also cite [3], which reports crucial experimental parameters pertaining to [1], e.g. chamber pressure during water target experiment. To correct the oversight of missing references, the 4th paragraph of the introduction follows with modified and additional text underlined:Liquid targets have a number of attractive features for meeting these needs. Liquid targets can be rapidly delivered into the interaction region, and mitigate debris [31,[34][35][36]. This is well illustrated by the pioneering research in [1, 3], who, for the first time combined a kHz, femtosecond laser and liquid jet targets with a long-term vision of developing integrated sources of energetic radiation and particles for future applications. They reported the production of 9.25 keV x-rays from the interaction of a kHz, 50 fs pulsed laser interacting with a liquid Ga jet target. They also reported the use of CR39 film to record the production of 500 keV protons from the interaction of the kHz laser with an intensity of 3×10 16 W cm −2 focused on a 10-30μm diameter water jet, with a background chamber pressure of 0.7-3 mbar. The proton production efficiency of 10 −5 % was reported. Prior to switching to the liquid sheet target described in our current work, we attempted to obtain protons from the interaction of 15-30μm diameter water jets with a 40 fs pulsed laser focused to an intensity of 1×10 18 W cm −2 . We recorded many tracks on the CR39 film but, when a magnetic spectrometer was used, all of the tracks were shown to be due to electrons. As noted in this paper, we later discovered that the chamber background pressure required to produce a significant flux of protons was below the freeze point pressure of water.Skip to the end of the last sentence of the paragraph and add as the last sentence of the paragraph: the ability to generate a well collimated proton beam with proton energies greater than 500 keV has recently been demonstrated [2], using a high repetition rate 0.5 kHz, 3 mJ, 55 fs laser interacting with a solid target. The focus intensity was 2×10 18 W cm −2 . A proton beam was generated at the front surface of a rotating optical quality glass disk at a chamber pressure of 3×10 −3 mbar. AbstractLaser acceleration of ions to MeV energies has been achieved on a variety of Petawatt laser systems, raising the prospect of ion beam applications using compact ultra-intense laser technology. However, translation from proof-of-concept laser experiment into real-world application requires MeV-scale ion energies and an appreciable repetition rate (>Hz). We demonstrate, for the first time, proton acceleration up to 2 MeV energies at a kHz repetition rate using a milli-joule-class short-pulse laser system. In these experiments, 5 mJ of ultrashort-pulse laser energy is delivered at an intensity neaŕ -5 10 W cm 18 2 onto a thin-sheet, liquid-density target. Key to this effort is a flowing liquid ethylene glycol target formed i...

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Section: Methodsmentioning

confidence: 99%

MeV proton acceleration at kHz repetition rate from ultra-intense laser liquid interaction

et al. 2018

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“…More quantitatively, while the laser-to-ejected-electron conversion efficiencies from 2D(3v) and 3D simulations with the same intensity and spot size were similar, the precise values were somewhat lower than the estimated lower bound conversion efficiency from experiment of 1.5% for electrons with kinetic energies greater than 120 keV. 2 In an effort to understand the angular and energy distribution of ejected electrons, we developed a parameterized analytic model that considers the dynamics of electrons that are accelerated initially by the standing wave fields and quasi-static electric fields present in the laser-interaction region. Later, these electrons experience the reflected laser pulse which we model as a plane wave.…”

Section: à2mentioning

confidence: 73%

“…Results will be summarized in Sec. III including a comparison to experimental measurements from Morrison et al 2 Finally, a discussion of these results will be presented in Sec. IV.…”

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confidence: 86%

“…While many research groups focus on highly relativistic laser intensities where the associated quiver velocity is large (a 0 ) 1), there are still interesting experiments to perform involving laser intensities near 10 18 W cm À2 where the electron dynamics are only moderately relativistic (a 0 $ 1). Importantly, at these intensities, current technology allows few-mJ laser pulses to be created at a kHz repetition rate, 1,2 which is advantageous for applications and for accumulating statistics. These intensities can also exhibit high reflectivity (տ70%) from near-solid density targets, 3 which is very unlike laser interactions at much higher intensity.…”

Section: Introductionmentioning

confidence: 99%

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Three dimensional particle-in-cell simulations of electron beams created via reflection of intense laser light from a water target

et al. 2016

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We present 3D Particle-in-Cell (PIC) modeling of an ultra-intense laser experiment by the Extreme Light group at the Air Force Research Laboratory (AFRL) using the PIC code LSP. This is the first time PIC simulations have been performed in 3D for this experiment which involves an ultra-intense, short-pulse (30 fs) laser interacting with a water jet target at normal incidence. These 3D PIC simulation results are compared to results from 2D(3v) PIC simulations for both 5.4 • 10 17 W cm −2 and 3 • 10 18 W cm −2 intensities. Comparing the 2D(3v) and 3D simulation results, the laser-energyto-ejected-electron-energy conversion efficiencies were comparable, but the angular distribution of ejected electrons show interesting differences with qualitative differences at higher intensity. An analytic plane-wave model is discussed which provides some explanation for the angular distribution and energies of ejected electrons in the 2D(3v) simulations. We also performed a 3D simulation with circularly polarized light and found a significantly higher conversion efficiency and peak electron energy, which is promising for future experiments.

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“…With regards to the applicability of the jet target, while not ideal for electron and ion acceleration due to the circular cross section, this particular target has found use due to More recent work using the nozzle assembly described in this work has been performed. Backward moving electron acceleration far exceeding ponderomotive scalings at 1 kHz repetition rate with relativistic intensities were demonstrated [64][65][66][67] .…”

Section: Liquid Jet Targetsmentioning

confidence: 99%

High-repetition-rate ( kHz) targets and optics from liquid microjets for high-intensity laser–plasma interactions

George

Morrison

Feister

et al. 2019

High Pow Laser Sci Eng

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High intensity laser-plasma interactions produce a wide array of energetic particles and beams with promising applications. Unfortunately, high repetition rate and high average power requirements for many applications are not satis ed by the lasers, optics, targets, and diagnostics currently employed. Here, we address the need for high repetition rate targets and optics through the use of liquids. A novel nozzle assembly is used to generate high-velocity, laminarowing liquid microjets which are compatible with a low-vacuum environment, generate li le to no debris, and exhibit precise positional and dimensional tolerances. Jets, droplets, submicron thick sheets, and other exotic con gurations are characterized with pump-probe shadowgraphy to evaluate their use as targets. To demonstrate a high repetition rate, consumable, liquid optical element, we present a plasma mirror created by a submicron thick liquid sheet. is plasma mirror provides etalon-like anti-re ection properties in the low-eld of 0.1% and high re ectivity as a plasma, 69%, at a repetition rate of 1 kHz. Practical considerations of uid compatibility, in-vacuum operation, and estimates of maximum repetition rate in excess of 10 kHz are addressed. e targets and optics presented here enable the use of relativistically intense lasers at high average power and make possible many long proposed applications. . All diode-pumped, highrepetition-rate advanced petawa laser system (hapls).

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Backward-propagating MeV electrons from 1018 W/cm2 laser interactions with water

Cited by 18 publications

References 34 publications

MeV proton acceleration at kHz repetition rate from ultra-intense laser liquid interaction

MeV proton acceleration at kHz repetition rate from ultra-intense laser liquid interaction

Three dimensional particle-in-cell simulations of electron beams created via reflection of intense laser light from a water target

High-repetition-rate ( kHz) targets and optics from liquid microjets for high-intensity laser–plasma interactions

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