Interaction of Short Petawatt Laser Pulses with Plasma
- Theory and Simulations

Laserlab Europe Workshop

Georg-Christoph-Lichtenberg-Haus, Darmstadt
October 14 - 17, 2007 -
Registered Participants Information

Title:	Dr.
Last Name:	Kostenko
First Name:	Oleg
E-Mail:	olegkostihed.ras.ru
Affiliation for Badge:	JIHT RAS, Moscow
Institute:	Joint Institute for High Temperatures of RAS
Address (Street):	Izhorskaya, 13/19
Postal Code, City:	125412 Moscow
Country:	Russia
Phone:	+7-495-485-9722
Fax:	+7-495-485-7990
Author(s):	KOSTENKO Oleg and ANDREEV Nikolay
Institute(s):	Joint Institute for High Temperatures, Russian Academy of Sciences, Moscow, Russia
Title:	Inverse bremsstrahlung heating of large metal clusters by intense femtosecond laser field
Abstract:	Spatial field structure and absorption cross-section analysis permits one to point out region of laser pulse and metal clusters parameters at which effective inverse bremsstrahlung heating play predominant role [1]. It is shown that usually used quasi-static expression for electric field inside a cluster and corresponding absorption cross-section are valid only in the zero order approximation on the ratio of cluster radius R to laser wavelength under the condition that skin depth d >> R. Even if d >> R, substantial contribution to the metal cluster heating can be made by induction electric field. In the opposite case (d << R) the use of quasi-static approximation can lead to strong underestimation of absorption cross-section. Models of the dense plasma dielectric function and ionization including ionization potential lowering are under discussion. Optimal for heating iron cluster radius (about 25 nm) is determined. Electron temperature at this radius amounts up to 3 keV at intensity about 10^18 W/cm^2 and pulse duration 100 fs. X-ray bremsstrahlung yield in the range of 1 - 2 keV is determined. The system of hydrodynamic equations for ion motion and Poisson-Boltzmann equation for electrons distribution was solved. At indicated parameters the outer field ionization of the cluster is small, so thermal electron pressure is greater than Coulomb pressure at the cluster surface. At the same time, the maximum ions energy is determined mainly by Coulomb energy of charged cluster. [1] Kostenko O.F., Andreev N.E. // Plasma Physics Reports. 2007. V. 33. N 6. P. 503.