Highly Efficient Relativistic-Ion Generation in the Laser-Piston Regime

An intense laser-plasma interaction regime of the generation of high density ultrashort relativistic ion beams is suggested. When the radiation pressure is dominant, the laser energy is transformed efficiently into the energy of fast ions.

Figure 1

(a) The ion density isosurface for $n=8n_{cr}$ (a quarter removed to reveal the interior) and the $x$ component of the normalized Poynting vector $(e/m_e\omega c{)}^2\mathbf{E}\times \mathbf{B}$ in the $(x,y=0,z)$ plane at $t=40\times 2\pi /\omega$. (b) The isosurface for $n=2n_{cr}$, green gas for lower density at $t=100\times 2\pi /\omega$; the black curve shows the ion density along the laser pulse axis.

Figure 2

The maximum ion kinetic energy versus time and the ion phase space projection $(x,p_x)$ at $t=80\times 2\pi /\omega$.

Figure 3

The energy spectrum (red) and transverse emittance (blue) of ions (solid) and electrons (dashed) located in the box $50\lambda <x<80\lambda$, $-\lambda <y$, $z<\lambda$ at $t=80\times 2\pi /\omega$. The hatched region contains $2.7\times {10}^{10}\mu {\mathrm{m}}^{-2}$ particles per cross section. Values correspond to $\lambda =1\mu \mathrm{m}$.

Figure 4

The electron phase space projection $(x,p_x)$ at $t=80\times 2\pi /\omega$ and longitudinal kinetic energy ${\mathcal{E}}_{e\parallel }=(m_e^2{c}^4+p_x^2{c}^2{)}^{1/2}-m_e{c}^2$ spectrum of electrons in the marked interval $67\lambda <x<80\lambda$.