Energetic proton generation from intense Coulomb explosion of large-size ethane clusters

Abstract

An experimental investigation is performed on the interaction of intense femtosecond laser pulses at the intensity of 6 × 1017 W/cm2 (55 fs, 160 mJ at 800 nm) with ethane cluster (C2H6)N jets prepared under the backing pressure of 30 bars at room temperature (298 K). The experiment results indicate the generation of energetic protons, whose average and maximum kinetic energies are 12.2 and 138.1 keV, respectively, by Coulomb explosion of (C2H6)N clusters. (C2H6)N clusters of 5 nm in radius are generated in the experiment, which are 1.7 times larger than that of (CH4)N clusters prepared in the same conditions. Empirical estimation suggests that (C2H6)N clusters with radius of about 9.6 nm can be prepared at 80-bars backing pressure at 308 K. While (C2H6)N clusters of so large size are irradiated by sufficiently intense laser pulses, the average energy of protons will be increased up to 50 keV. It is inferred that such large-size deuterated ethane clusters (C2D6)N will favor more efficient neutron generation due to the significant increase of the D-D nuclear reaction cross section in laser-driven cluster nuclear fusion.