HELEN Laser target interaction chamber showing the beam path of the short-pulse (CPA) beam and the beam cones for the long pulse beams.
(a) Predicted focal spot intensity distribution calculated from aberration corrected beam wave front data, (b) line profile through calculated focal spot diameter showing diameter of the first dark ring of the Airy-disk like intensity distribution.
X-ray pinhole image of laser heat spot of CPA beam at best focus on an aluminium target foil. Pinhole diameter is filtered by a thick aluminium foil.
Horizontal diameter line profile through x-ray pinhole image of laser heated spot. Raw data—gray and fit to data—solid.
Maximum proton energy from time of flight measurements as a function of . HELEN CPA beam data in blocked in diamonds.
(Color online) Scanned images of radiochromic film (upper) and CR39 (lower) stack for a focused intensity of on thick aluminium foil showing signal principally due to energetic protons. Stack sequence from front to back: Al/RCF(a)/CR39(a)/⋯/RCF(f)/CR39(f).
Proton energy spectrum from calibrated radiochromic film/CR39 stack for a focused intensity of on thick aluminium foil target.
Layout of TLD tungsten collimator array relative to the short-pulse laser axis. Each collimator contains five filtered capsules containing TLD powder.
Relative spectral response of TLD detectors used in collimated array.
Angular absorbed dose in filtered TLD array for at best focus incident of thick tantalum foil (HELEN—solid line) and thick tantalum (Vulcan laser—broken line).
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