|
We propose a semi-analytical model for non-relativistic Coulomb explosion of a uniformly charged spheroid
[1], applicable to the so-called vertical ionization regime where electrons are expelled on a time much shorter
than the characteristic time of ion motion. The model allows one to derive the time-dependent particle energy
distributions. Simple expressions are given for the characteristic explosion time and maximum particle
energies in the limits of extreme prolate and oblate spheroids as well as for the sphere. Our theoretical
predictions are found to be in remarkably good agreement with particle (both molecular-dynamics and
particle-in-cell) simulations. Our results may give simple design guidelines how to optimize target properties;
for example, for inertial fusion applications [2] or for ion acceleration from laser-solid interaction
which is characterized by the emission of short, compact, and highly-charged ion bunches. Propagation of
these bunches (e.g., through a vacuum) is strongly affected by space charge effects [3,4]. By approximating
the accelerated ion bunches as uniformly charged spheroids, the results presented here allows to derive the
conditions required for limited energy and angular dispersions.
References [1] M. Grech, R. Nuter, A. Mikaberidze, P.F. Di Cintio, L. Gremillet, E. Lefebvre, U. Saalmann, J.M. Rost, and S. Skupin, Phys. Rev. E 84, 056404 (2011). [2] T. Desai, J. T. Mendonca, D. Batani, and A. Bernadinello, Cluster Induced IgnitionA New Approach to Inertial Fusion Energy, 18th Fusion Energy Conference, 2000, Sorrento, Italy; proceedings available at [www.iaea.org/programmes/ ripc/physics/fec2000/html/node273.html]. [3] M. Grech, S. Skupin, R. Nuter, L. Gremillet, and E. Lefebvre, New J. Phys. 11, 093035 (2009); Nucl. Instrum. Methods Phys. Res., Sect. A 620, 63 (2010). [4] V. T. Tikhonchuk, Nucl. Instrum. Methods Phys. Res., Sect. A 620, 1 (2010). |
|