Abstract:A theoretical and numerical investigation of non-ponderomotive absorption at laser intensities relevant to quantum electrodynamics is presented. It is predicted that there is a regime change in the dependence of fast electron energy on incident laser energy that coincides with the onset of pair production via the Breit-Wheeler process. This prediction is numerically verified via an extensive campaign of QED-inclusive particle-in-cell simulations. The dramatic nature of the power law shift leads to the conclusi… Show more
“…Our studies are in agreement with the Savin et al. (2019) calculated results for corresponding and scale length between 0 and with and without QED cases. Figure 16.Calculated electron temperature as a function of plasma scale length with (, blue) and without (, red) QED cases.…”
Section: Energy Spectra Of Accelerated Particlessupporting
confidence: 93%
“…Savin et al. (2019) claims that without QED and with QED effects. Since a small fixed amount of scale length () was used in their simulations, Savin et al.…”
Section: Energy Spectra Of Accelerated Particlesmentioning
confidence: 99%
“…Recent simulations with and showed that ultraintense () laser–solid interactions generate a new electron acceleration mechanism called the zero-vector-potential (ZVP) absorption mechanism, which produces electrons with higher temperatures (Savin et al. 2019). The qualitative evidence of the ZVP mechanism can be seen graphically through high momentum spikes on the laser propagation axis.…”
In this work, simulations of multipetawatt lasers at irradiances
${\sim }10^{23} \ \mathrm {W}\ \mathrm {cm}^{-2}$
, striking solid targets and implementing two-dimensional particle-in-cell code was used to study particle acceleration. Preformed plasma at the front surface of a solid target increases both the efficiency of particle acceleration and the reached maximum energy by the accelerated charged particles via nonlinear plasma processes. Here, we have investigated the preformed plasma scale length effects on particle acceleration in the presence and absence of nonlinear quantum electrodynamic (QED) effects, including quantum radiation reaction and multiphoton Breit–Wheeler pair production, which become important at irradiances
${\sim } 10^{23}\ \mathrm {W}\ \mathrm {cm}^{-2}$
. Our results show that QED effects help particles gain higher energies with the presence of preformed plasma. In the results for all cases, preplasma leads to more efficient laser absorption and produces more energetic charged particles, as expected. In the case where QED is included, however, physical mechanisms changed and generated secondary particles (
$\gamma$
-rays and positrons) reversing this trend. That is, the hot electrons cool down due to QED effects, while ions gain more energy due to different acceleration methods. It is found that more energetic
$\gamma$
-rays and positrons are created with increasing scale length due to high laser conversion efficiency (
${\sim }$
24 % for
$\gamma$
-rays and
$\sim$
4 % for positrons at
$L = 7\ \mathrm {\mu }\textrm {m}$
scale length), which affects the ion and electron acceleration mechanisms. It is also observed that the QED effect reduces the collimation of angular distribution of accelerated ions because the dominant ion acceleration mechanism is changing when QED is involved in the process.
“…Our studies are in agreement with the Savin et al. (2019) calculated results for corresponding and scale length between 0 and with and without QED cases. Figure 16.Calculated electron temperature as a function of plasma scale length with (, blue) and without (, red) QED cases.…”
Section: Energy Spectra Of Accelerated Particlessupporting
confidence: 93%
“…Savin et al. (2019) claims that without QED and with QED effects. Since a small fixed amount of scale length () was used in their simulations, Savin et al.…”
Section: Energy Spectra Of Accelerated Particlesmentioning
confidence: 99%
“…Recent simulations with and showed that ultraintense () laser–solid interactions generate a new electron acceleration mechanism called the zero-vector-potential (ZVP) absorption mechanism, which produces electrons with higher temperatures (Savin et al. 2019). The qualitative evidence of the ZVP mechanism can be seen graphically through high momentum spikes on the laser propagation axis.…”
In this work, simulations of multipetawatt lasers at irradiances
${\sim }10^{23} \ \mathrm {W}\ \mathrm {cm}^{-2}$
, striking solid targets and implementing two-dimensional particle-in-cell code was used to study particle acceleration. Preformed plasma at the front surface of a solid target increases both the efficiency of particle acceleration and the reached maximum energy by the accelerated charged particles via nonlinear plasma processes. Here, we have investigated the preformed plasma scale length effects on particle acceleration in the presence and absence of nonlinear quantum electrodynamic (QED) effects, including quantum radiation reaction and multiphoton Breit–Wheeler pair production, which become important at irradiances
${\sim } 10^{23}\ \mathrm {W}\ \mathrm {cm}^{-2}$
. Our results show that QED effects help particles gain higher energies with the presence of preformed plasma. In the results for all cases, preplasma leads to more efficient laser absorption and produces more energetic charged particles, as expected. In the case where QED is included, however, physical mechanisms changed and generated secondary particles (
$\gamma$
-rays and positrons) reversing this trend. That is, the hot electrons cool down due to QED effects, while ions gain more energy due to different acceleration methods. It is found that more energetic
$\gamma$
-rays and positrons are created with increasing scale length due to high laser conversion efficiency (
${\sim }$
24 % for
$\gamma$
-rays and
$\sim$
4 % for positrons at
$L = 7\ \mathrm {\mu }\textrm {m}$
scale length), which affects the ion and electron acceleration mechanisms. It is also observed that the QED effect reduces the collimation of angular distribution of accelerated ions because the dominant ion acceleration mechanism is changing when QED is involved in the process.
“…Tremendous effects have been made to understand the QED plasma dynamics [28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47] and to explore possibilities of their preparation in laboratories [48][49][50][51][52][53][54][55][56][57][58][59][60] . The QED plasma dynamics 9,[60][61][62] is characterized by strong field QED and collective plasma effects.…”
Section: Introductionmentioning
confidence: 99%
“…It was proposed 48 that laser intensities above 10 24 Wcm −2 is sufficient to probe the QED critical field in the particle rest frame. This all-optical method has prompted investigation both analytically and numerically [48][49][50][51][52][53][54][55][56][57][58][59] . However, the 10 24 Wcm −2 laser intensity required by the all-optical method needs a highly non-trivial tight focus of a 100 PW laser [81][82][83] .…”
Understanding the interplay of strong-field QED and collective plasma effects is important for explaining extreme astrophysical environments like magnetars. It has been shown that QED pair plasmas is possible to be produced and observed by passing a relativistic electron beam through an intense laser field. This paper presents in detail multiple sets of 3D QED-PIC simulations to show the creation of pair plasmas in the QED cascade. The beam driven method enables a high pair particle density and also a low particle gamma factor, which both play equal rolls on exhibiting large collective plasma effects. Finite laser frequency upshift is observed with both ideal parameters (24 PW laser laser colliding with 300 GeV electron beam) and with existing technologies (3 PW laser laser colliding with 30 GeV electron beam).
The commissioning of multi-petawatt class laser facilities around the world is gathering pace. One of the primary motivations for these investments is the acceleration of high-quality, low-emittance electron bunches. Here we explore the interaction of a high-intensity femtosecond laser pulse with a mass-limited dense target to produce MeV attosecond electron bunches in transmission and confirm with three-dimensional simulation that such bunches have low emittance and nano-Coulomb charge. We then perform a large parameter scan from non-relativistic laser intensities to the laser-QED regime and from the critical plasma density to beyond solid density to demonstrate that the electron bunch energies and the laser pulse energy absorption into the plasma can be quantitatively described via the Zero Vector Potential mechanism. These results have wide-ranging implications for future particle accelerator science and associated technologies.
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