Fyzikální ústav Akademie věd ČR

Study of atomic ion acceleration in laser plasma, laser ion sources

Generation and acceleration of highly-charged heavy atomic ions during expansion of laser plasma induced by a nanosecond laser pulse occur at a plasmatic corona produced by electron collisions. Therefore, the observed properties of ion beams depend on a kinetic of an electron gas in the plasma. We use carbon, fluor, copper, iron, gold, and tantalum targets, particularly. The highest kinetic energy of a proton beam was up to 2 MeV and of the other ions was about 1MeV/nucleon [1,2]. Heavy ion charge numbers of the gold and tantalum were near to 50+ or even higher.

We believe to be the first, who proved experimentally that an unexpected high efficiency of the laser-pumped ion source is caused by a self-focusing or filamentation of the laser beam and thus we helped to explain a structure of emitted ion groups. We also showed experimentally that proposed high repetition hybrid ion sources for common particle accelerators really can be pumped by a high repetition lasers in spite of a relatively weak pump intensity.

Touching a physical field of laser astrophysics, there was a surprising discovery of spontaneous plasma jets from targets of heavier elements against a direction of laser beam, which persisted many nanoseconds after a decay time of the laser pulse. The jets had many hydrodynamic similarity conditions very close to near jets of planetary nebulae and similar objects of our Galaxy.

Our new detectors of laser-generated fast ions, developed in a collaboration with the institutes of IPPLM Varsaw and INFN Catania, are used also for a diagnostics of other fast plasma ion sources, e.g. plasma focus.

[1] L. Láska, S. Cavallaro, K. Jungwirth, J. Krása, E. Krouský, D. Margarone, A. Mezzasalma, M. Pfeifer, K. Rohlena, L. Ryc, J. Skála, L. Torrisi, J. Ullschmied, A. Velyhan, G. Verona-Rinati
Experimental studies of emission of highly charged Au-ions and of X-rays from the laser-produced plasma at high laser intensities
Eur. Phys. J. D 54 (2009) 487 - 492. doi: 10.1140/epjd/e2008-00226-8

[2] L. Láska, J. Krása, A. Velyhan, K. Jungwirth, E. Krouský, D. Margarone, M. Pfeifer, K. Rohlena, L. Ryc, J. Skála, L. Torrisi, J. Ullschmied
Experimental studies of generation of similar to 100 MeV Au-ions from the laser-produced plasma
Laser Part. Beams 27 (2009) 137 - 147. doi: 10.1017/S0263034609000202