Simulation of the interaction of high-energy C60 cluster ions with amorphous targets

Detailed simulations of the interaction of energetic C-60 beams with amorphous targets are presented here. The spatial evolution of the cluster components is calculated accounting for multiple scattering and Coulomb explosion by means of Monte Carlo and molecular dynamics, respectively. The charge states of the individual cluster components (atoms, atomic ions, fragment cluster ions) as a function of penetration depth are also calculated in tandem with the above calculations by means of the Monte Carlo method. The relative importance of scattering versus Coulomb repulsion is studied as a function of the C-60 cluster energy. The effect of the neighboring cluster constituents on the average charge state of the cluster atoms is calculated as a function of the depth of penetration for a C-60 cluster of 40 MeV. The calculation accounts for the increase in ionization energy of the atom due to the other constituents. Relative track radii are calculated as a function of penetration depth and good agreement with the experimental results is obtained for the interaction of a 30 MeV carbon cluster with silicon. Track splitting observed well into the target as measured by Dunlop in yttrium iron garnet is obtained in the simulations described here for the case of amorphous carbon, provided the Coulomb repulsion is screened by the four valence electrons. Collective energy deposition enhancement is calculated for the 720 MeV cluster. Here the cluster constituents are nearly fully ionized, thereby minimizing the ambiguity related to the value of the ionic charge in the calculation

DIAGNOSTIC TECHNIQUES FOR INTENSE PARTICLE BEAM-TARGET INTERACTION USING K[MATH] RADIATION

On propose comme diagnostic les rayonnements x/Kα émis durant l'interaction d'un faisceau intense d'ions avec une cible. Les expériences proposées mettent en jeu un pouvoir d'arrêt amplifié. Les mesures de température et l'opacité de la raie Kα sont simulées en détail. Les techniques expérimentales ont déjà été utilisées pour des faisceaux intenses d'électrons. Elles sont décrites ici.Kα x rays emitted during the interaction of an intense ion beam with a target is proposed as a diagnostic. Tne proposed experiments which deal with enhanced stopping power, temperature measurements and Kα line opacity were simulated in detail. The experimental techniques were used in intense electron beam experiments and are also described here

PLASMA EFFECTS IN ION BEAM TARGET INTERACTION

On présente trois exemples où les processus mis en jeu dans l'interaction de faisceaux de particules chargées sont affectés par le fait que la cible est un plasma à forte densité d'énergie : 1. Effets de plasma sur le pouvoir d'arrêt. 2. Effets de plasma sur l'état de charge des ions rapides. 3. Effets de l'opacité du plasma importants pour l'interprétation des mesures spectroscopiques.We point out three examples of cases in which processes involved in the interaction of charged particle beams are affected by the fact that the target is a high energy density plasma : 1. Plasma effects on the stopping power. 2. Plasma effects on the charge state of fast ions. 3. Plasma opacity effects important in the interpretation of spectroscopic measurements

DIELECTRONIC RECOMBINATION IN THE AVERAGE-ATOM MODEL

Autoionization and dielectronic attachment are usually omitted from rate equations for the non-LTE average-atom model, causing systematic errors in predicted ionization states and electronic populations for atoms in hot dense plasmas produced by laser irradiation of solid targets. We formulate a method by which dielectronic recombination can be included in average-atom calculations without conflict with the principle of detailed balance. The essential new feature in this extended average atom model is a treatment of strong correlations of electron populations induced by the dielectronic attachment proces

HEATING OF SOLIDS WITH ULTRA-SHORT LASER PULSES

Cet article présente une analyse théorique du chauffage des solides par des impulsions laser ultra-courtes, de l'ordre de la femtoseconde. Les profils spatio-temporels de température sont déterminés et des techniques de diagnostic proposées. Il est possible d'obtenir des plasmas chauds avec de fortes densités, connues de manière précise. Ce qui rend possible la détermination des propriétés des matériaux dans un nouveau domaine intéressant de paramètres.This paper gives a theoretical analysis of the heating of solids by ultra short-pulse lasers in the femtosecond time domain. Time and space profiles of the temperature are calculated and diagnostic techniques are proposed. It is found that one can produce hot plasmas of accurately known high density, making possible the measurement of material properties in an interesting new parameter range