Selective deuterium ion acceleration using the Vulcan petawatt laser

Abstract

We report on the successful demonstration of selective acceleration of deuterium ions by targetnormal sheath acceleration (TNSA) with a high-energy petawatt laser. TNSA typically produces a multi-species ion beam that originates from the intrinsic hydrocarbon and water vapor contaminants on the target surface. Using the method first developed by Morrison et al. [Phys. Plasmas 19, 030707 (2012)], an ion beam with >99% deuterium ions and peak energy 14 MeV/nucleon is produced with a 200 J, 700 fs, >10 20 W=cm 2 laser pulse by cryogenically freezing heavy water (D 2 O) vapor onto the rear surface of the target prior to the shot. Within the range of our detectors (0 -8.5 ), we find laser-to-deuterium-ion energy conversion efficiency of 4.3% above 0.7 MeV/ nucleon while a conservative estimate of the total beam gives a conversion efficiency of 9.4%. V C 2015 AIP Publishing LLC. [http://dx.

High flux, beamed neutron sources employing deuteron-rich ion beams from D2O-ice layered targets

“…As shown in ref. [33], the ice-layered target typically produced deuterons upto 30 MeV/nucleon, which, based on the reaction kinematics, is consistent with the highest energy neutrons observed along the beam axis (see Fig. 3(b)).…”

“…[8]. According to the kinematic of the d(d,n) 3 He reaction (E n = (E d /8) 8,43], where E d and E n represent the deuterium and neutron energies respectively along the axis and Q the Q-value of the reaction), such neutron energy would be expected from a beam-fusion scenario employing ∼ 36 MeV deuterons, which is similar to the maximum deuterium energy measured experimentally from the ice-layered targets [33].…”

“…In our case the hydrocarbon contaminants were buried underneath a D 2 O ice layer, which produced ion beams highly dominated by deuterons, as shown in Fig. 2(c), with an estimated laser-to-deuteron energy conversion efficiency of ∼ 9% and a maximum deuteron energy up to 29 MeV [33]. The absolute spectra for both proton and deuterium ions obtained from the icelayered target are shown in Fig.…”

“…The ice layer buries the proton-rich contaminant layers and therefore optimises the acceleration of deuterium, being the lightest ion species at the rearmost surface of the laser-irradiated target. A 99%-pure deuteron beam was demonstrated recently by Krygier et al [33] using D 2 O ice covered targets at Vulcan petawatt laser, with a laser-to-deuteron energy conversion efficiency above 9%.…”

Recent developments in the Thomson Parabola Spectrometer diagnostic for laser-driven multi-species ion sources

“…2(c-2)). This technique has been successfully implemented in a number of experiments studying laser driven deuterons produced under different conditions [40,43].…”