Multi-MeV ion beams from terawatt laser thin-foil interactions

We have conducted investigations of a collimated beam of fast protons, produced by a 10TW laser with frequencies of either ω₀ (corresponding to 1.053 micron light) or 2ω ₀ (corresponding to 532 nm light) focused to an intensity of more the 3×10¹⁹ W/cm² onto the surface of a thin-film target. Energies as high as 10 MeV and total number of 10⁹, confined in a cone angle of 40°±10° have been observed. The protons, which originate form impurities on the front side of the target and exit out the backside in a direction normal to the target surface. Acceleration field gradients of ~10 GeV/cm have been inferred. The maximum proton energy for 2ω₀ can be explained by the charge-separation electrostatic-field acceleration due to "vacuum heating". In another set of experiments when a deuterated polystyrene layer was deposited on a surface of a Mylar film and a ¹⁰B sample was placed behind the target, we observed the production of ~10⁵ atoms of positron active isotope ¹¹ C from the nuclear fusion reaction ¹⁰B(d,n)¹¹C. No activation was detected when only the proton beam was used. We also discuss the use of ions from these table-top sources for medical applications such as cancer radiotherapy and fundamental studies in radio-biology