Time-resolved Rayleigh scattering measurements of methane clusters for laser-cluster fusion experiments

We present a time-resolved analysis of Rayleigh scattering measurements to determine the average size of methane clusters and find the optimum timing for laser-cluster fusion experiments. We measure Rayleigh scattering and determine the average size of methane clusters varying the backing pressure ( P 0 ) from 11 bar to 69 bar. Regarding the onset of clustering, we estimate that the average size of methane clusters at the onset of clustering is N c0 ≅20 at 11 bar. According to our measurements, the average cluster radius r follows the power law of r ∝ P 0 1.86 . Our ion time-of-flight measurements indicate that we have produced energetic deuterium ions with kT = 52±2 keV after laser-cluster interaction using CD 4 gas at 50 bar. We find that this ion temperature agrees with the predicted temperature from CD 4 clusters at 50 bar with r = 14 nm assuming the Coulomb explosion model.