arXiv subjects

A. P. L. Robinson

Publications and source records attributed to A. P. L. Robinson.

22 records · Page 2Linked to original sources

arXiv2012

Dynamics of self-generated, large amplitude magnetic fields following high-intensity laser matter interaction

The dynamics of magnetic fields with amplitude of several tens of Megagauss, generated at both sides of a solid target irradiated with a high intensity (? 1019W/cm2) picosecond laser pulse, has been spatially and temporally resolved using a proton imaging technique. The amplitude of the magnetic fields is sufficiently large to have a constraining effect on the radial expansion of the plasma sheath at the target surfaces. These results, supported by numerical simulations and simple analytical modeling, may have implications for ion acceleration driven by the plasma sheath at the rear side of the target as well as for the laboratory study of self-collimated high-energy plasma jets.

physics.plasm-ph↗

arXiv2012

Dense Electron-Positron Plasmas and Ultra-Intense Bursts of Gamma-Rays from Laser-Irradiated Solids

In simulations of a 10PW laser striking a solid we demonstrate the possibility of producing a pure electron-positron plasma by the same processes as those thought to operate in high-energy astrophysical environments. A maximum positron density of 10^26/m^3 is achieved, seven orders of magnitude greater than achieved in previous experiments. Additionally, 35% of the laser energy is converted to a burst of gamma-rays of intensity 10^22W/cm^2, potentially the most intense gamma-ray source available in the laboratory. This absorption results in a strong feedback between both pair and gamma-ray production and classical plasma physics in the new `QED-plasma' regime.

physics.plasm-ph↗

arXiv2010

Zero vector potential mechanism of attosecond absorption in strongly relativistic plasmas

The understanding of the physics of lasermatter interactions in the strongly relativistic regime is of fundamental importance. In this article, a new mechanism of fast electron generation at the vacuum-solid boundary of intense laser pulse interaction with overdense plasma is described. It is one that has no analogue in classical, non-relativistic laser-plasma interactions. Here, conclusive proof is provided that the key contribution to the fast electron generation is given by the zero points of the vector potential. We demonstrate that the new mechanism leads to scalings for the fast electron energy, which explicitly depend on the plasma density, thus providing a new insight into relativistic laser-matter interaction. Furthermore, it is shown that this new mechanism provides the dominant contribution to the interaction by the injection of energy into the overdense plasma delivered by attosecondduration electron bunches. This new understanding will allow the future generation of a single ultra-bright attosecond X-ray pulse by suitable control of the laser pulse polarization [1]-[7]. This process will also allow single pulse attosecond electron bunches to be generated that can be further accelerated in laser wakefield accelerators [8]-[10]. Other applications that will benefit from this new insight include laser driven ion accelerators [11]-[15], fast ignition inertial confinement fusion [16]-[18] as well as fundamental studies at the intensity frontier [19]-[20].

physics.plasm-ph↗

arXiv2007

Radiation Pressure Acceleration of Thin Foils with Circularly Polarized Laser Pulses

A new regime is described for Radiation Pressure Acceleration of a thin foil by an intense laser beam of above 10^20 W/cm^2. Highly monoenergetic proton beams extending to GeV energies can be produced with very high efficiency using circularly polarized light. The proton beams have a very small divergence angle (less than 4 degrees). This new method allows the construction of ultra-compact proton and ion accelerators with ultra-short particle bursts.

physics.plasm-ph↗