Computer simulations of Coulomb explosions of clusters induced by ultraintense ultrashort laser pulses
|Research Area||Plasma & Particle Physics|
|Principal Investigator(s)||Dr. Andreas Heidenreich|
Irradiation of atomic and molecular clusters by ultraintense (1015-1021 Wcm-2) and ultrashort laser pulses (10-250 fs) leads via barrier suppression ionization and electron impact ionization to extreme ionizations of all atoms, e.g. in Xe clusters up to Xe36+. The stripped electrons form, together with their parent ions, a nanoplasma within the cluster, before the highly charged cluster undergoes a Coulomb explosion. Thereby, the ion kinetic energies are so high that nuclear fusion can occur, when hydrogen isotopes are involved. Nuclear fusion can occur between ions of different clusters inside the cluster beam (intercluster fusion) or between ions of the same cluster (intracluster fusion). Intracluster fusion can occur, if ions in the cluster interior expand faster into space than ions in the cluster periphery ("nuclear overrun effect"). A nuclear overrun is observed for ions with different charge/mass ratios and/or sufficient density homogeneities in the cluster. Heavy, highly charged ions like Xe36+ increase the kinetic energy of light atoms substantially by high electrostatic repulsion and by kinematic effects ("energy boosting").
Our particle trajectory calculations describe the electron and nuclear dynamics of the cluster and its interactions with the laser field. Electrons are treated relativistically but non-quantum mechanically, which is justified by their high kinetic energies.
In our simulations we focus on the energetics and dynamics of the following systems: (1) Large xenon clusters (Xe12000), (2) Energy boosting of large helium clusters (He100000) by an embedded medium size xenon cluster (Xe1000), and (3) D(d,n)4He and 3He(d,p)4He intracluster nuclear fusion yields in (D2)k and (D2)k(3He)m clusters with an embedded Xen cluster. Since extremely large clusters (~109 atoms) are needed to achieve appreciable intracluster fusion yields, a scaled particle simulation scheme will be employed, which reduces the number of propagated particles by scaling all particle charges and masses by a uniform factor.