Generation of bright collimated vortex $\gamma$-ray via laser driven cone-fan target

Abstract

We use numerical simulations to demonstrate that a source of bright collimated vortex $\gamma$-ray with large orbital angular momentum can be achieved by irradiating a circularly polarized laser with an intensity about $10^{22}W/\mathrm{c}{\mathrm{m}}^2$ on a cone-fan target. In the studied setup, electron beam of energy of hundreds of MeV and vortex laser pulse are formed. And furthermore a high quality vortex $\gamma$-ray is yielded with small divergence of $5^{\circ }$ and high peak brilliance $\sim 5\times 10^{22}$ photons $\cdot {\mathrm{s}}^{-1}\cdot \mathrm{m}{\mathrm{m}}^{-2}\cdot \mathrm{mra}{\mathrm{d}}^{-2}$ $0.1\%\mathrm{BW}$ at $10\mathrm{MeV}$. A considerable fraction of angular momentum of laser is converted to electron beam and vortex $\gamma$-ray, which are roughly $27.8\%$ and $3\%$, respectively. And the conversion efficiency of energy from laser to electron beam and vortex $\gamma$-ray are around $41\%$ and $3.8\%$. Moreover, comparative simulations for different right radius of cone reveal that there exists an optimal size that makes the highest angular momentum of $\gamma$-ray photons to be around $2.8\times 10^6\hslash$. The comparative simulations for different laser modes exhibit that it is more appropriate to choose the circularly polarized laser to generate vortex $\gamma$-ray than the Laguerre-Gaussian one.

18 pages, 9 figures

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Cited by in corpus (1)

• Plasma acceleration of polarized particle beams