Enhancement of J x B electron acceleration with the micro-structured target and picosecond high-contrast relativistic-intensity laser pulse

Fuente: arXiv
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Autori principali: Takizawa, Ryunosuke, Karaki, Yuga, Matsubara, Hiroki, Akematsu, Rinya, Oomura, Ryou, Farley, Law King Fai, Azechi, Hiroshi, Iwata, Natsumi, Johzaki, Tomoyuki, Sentoku, Yasuhiko, Fujioka, Shinsuke
Natura: Preprint
Pubblicazione: 2025
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author Takizawa, Ryunosuke
Karaki, Yuga
Matsubara, Hiroki
Akematsu, Rinya
Oomura, Ryou
Farley, Law King Fai
Azechi, Hiroshi
Iwata, Natsumi
Johzaki, Tomoyuki
Sentoku, Yasuhiko
Fujioka, Shinsuke
author_facet Takizawa, Ryunosuke
Karaki, Yuga
Matsubara, Hiroki
Akematsu, Rinya
Oomura, Ryou
Farley, Law King Fai
Azechi, Hiroshi
Iwata, Natsumi
Johzaki, Tomoyuki
Sentoku, Yasuhiko
Fujioka, Shinsuke
contents Efficient generation of multi-hundred-keV electrons is essential for isochoric heating and can influence ion acceleration. We investigated electron acceleration from copper-oleate foil targets, either planar or coated with a gold mesh structure (bar width $5,μ\mathrm{m}$, spacing $7.5,μ\mathrm{m}$, thickness $\sim6,μ\mathrm{m}$), irradiated by $1.5$-ps, $350$-J LFEX laser pulses. Two laser-contrast conditions were examined: high ($\sim10^{10}$, with a plasma mirror) and low ($\sim10^{8}$, without a plasma mirror). Using Cu-K$_α$ emission mapping, we found that under high-contrast irradiation the micro-structured target enhanced the laser-to-electron conversion efficiency from $4.9\%$ to $14\%$, attributed to multiple internal reflections that strengthen $J\times B$ acceleration. In contrast, under low-contrast conditions the structures were filled with pre-plasma before the main pulse, and no enhancement was observed. These results demonstrate that both fine-scale structuring and high contrast are crucial for maximizing $J\times B$-driven electron generation in laser-plasma interactions. Our findings suggest a practical approach to improving laser-plasma coupling efficiency by exploiting micro-structured surfaces and contrast-controlled irradiation.
format Preprint
id arxiv_https___arxiv_org_abs_2506_21847
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Enhancement of J x B electron acceleration with the micro-structured target and picosecond high-contrast relativistic-intensity laser pulse
Takizawa, Ryunosuke
Karaki, Yuga
Matsubara, Hiroki
Akematsu, Rinya
Oomura, Ryou
Farley, Law King Fai
Azechi, Hiroshi
Iwata, Natsumi
Johzaki, Tomoyuki
Sentoku, Yasuhiko
Fujioka, Shinsuke
Plasma Physics
Efficient generation of multi-hundred-keV electrons is essential for isochoric heating and can influence ion acceleration. We investigated electron acceleration from copper-oleate foil targets, either planar or coated with a gold mesh structure (bar width $5,μ\mathrm{m}$, spacing $7.5,μ\mathrm{m}$, thickness $\sim6,μ\mathrm{m}$), irradiated by $1.5$-ps, $350$-J LFEX laser pulses. Two laser-contrast conditions were examined: high ($\sim10^{10}$, with a plasma mirror) and low ($\sim10^{8}$, without a plasma mirror). Using Cu-K$_α$ emission mapping, we found that under high-contrast irradiation the micro-structured target enhanced the laser-to-electron conversion efficiency from $4.9\%$ to $14\%$, attributed to multiple internal reflections that strengthen $J\times B$ acceleration. In contrast, under low-contrast conditions the structures were filled with pre-plasma before the main pulse, and no enhancement was observed. These results demonstrate that both fine-scale structuring and high contrast are crucial for maximizing $J\times B$-driven electron generation in laser-plasma interactions. Our findings suggest a practical approach to improving laser-plasma coupling efficiency by exploiting micro-structured surfaces and contrast-controlled irradiation.
title Enhancement of J x B electron acceleration with the micro-structured target and picosecond high-contrast relativistic-intensity laser pulse
topic Plasma Physics
url https://arxiv.org/abs/2506.21847