The collimating effect of self-generated magnetic fields on fastelectron transport in solid aluminium targets irradiated by ultra-intense, picosecond laser pulses is investigated in this study. As the target thickness is varied in the range of 25μm to 1.4 mm, the maximum energies of protons accelerated from the rear surface are measured to infer changes in the fast-electron density and therefore the divergence of the fast-electron beam transported through the target. Purely ballistic spreading of the fast-electrons would result in a much faster decrease in the maximum proton energy with increasing target thickness than that measured. This implies that some degree of ‘global’ magnetic pinching of the fast-electrons occurs, particularly for thick (>400μm) targets. Numerical simulations of electron transport are in good agreement with the experimental data and show that the pinching effect of the magnetic field in thin targets is significantly reduced due to disruption of the field growth by refluxing fast-electrons.
Effect of self-generated magnetic fields on fast-electron beam divergence in solid targets / X. H., Yuan; A. P. L., Robinson; M. N., Quinn; D. C., Carroll; M., Borghesi; R. J., Clarke; R. G., Evans; J., Fuchs; P., Gallegos; Lancia, Livia; D., Neely; K., Quinn; L., Romagnani; G., Sarri; P. A., Wilson; P., Mckenna. - In: NEW JOURNAL OF PHYSICS. - ISSN 1367-2630. - 12:6(2010), p. 063018. [10.1088/1367-2630/12/6/063018]
Effect of self-generated magnetic fields on fast-electron beam divergence in solid targets
LANCIA, LIVIA;
2010
Abstract
The collimating effect of self-generated magnetic fields on fastelectron transport in solid aluminium targets irradiated by ultra-intense, picosecond laser pulses is investigated in this study. As the target thickness is varied in the range of 25μm to 1.4 mm, the maximum energies of protons accelerated from the rear surface are measured to infer changes in the fast-electron density and therefore the divergence of the fast-electron beam transported through the target. Purely ballistic spreading of the fast-electrons would result in a much faster decrease in the maximum proton energy with increasing target thickness than that measured. This implies that some degree of ‘global’ magnetic pinching of the fast-electrons occurs, particularly for thick (>400μm) targets. Numerical simulations of electron transport are in good agreement with the experimental data and show that the pinching effect of the magnetic field in thin targets is significantly reduced due to disruption of the field growth by refluxing fast-electrons.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
