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Ter-Avetisyan, S.*; Schn
rer, M.*; Nickles, P. V.*; Sandner, W.*; Borghesi, M.*; Nakamura, Tatsufumi; Mima, Kunioki*
Physics of Plasmas, 17(6), p.063101_1 - 063101_6, 2010/06
Times Cited Count：8 Percentile：31.2(Physics, Fluids & Plasmas)Using a multichannel Thomson spectrometer we have implemented a tomographic approach allowing the reconstruction of the emission characteristics of a laser driven proton source with high energy and spatial resolution. The results demonstrate the complexity of the temporal and spatial characteristics of such a source. The emitted proton beam, which is laminar and divergent ant high energies, becomes convergent at low energies. This implies that a fraction of the proton beam having this kinetic energy is emitted in a collimated way from the target at the turning point between these tow behaviors. Only a finite fraction of the target surface is contributing to the ion spectrum, which is measured at a specific angle within the beam cone. Therefore the momentum distribution of the protons in the emitted beam at any point in space can be controlled by determining the proton source area.
Ter-Avetisyan, S.*; Schnrer, M.*; Nickles, P. V.*; Sandner, W.*; Nakamura, Tatsufumi; Mima, Kunioki*
Physics of Plasmas, 16(4), p.043108_1 - 043108_6, 2009/04
Times Cited Count：26 Percentile：69.11(Physics, Fluids & Plasmas)The laser driven ion source is highly organized dynamical system. It relies on a well defined interaction between the spatial and momentum distributions of emitted ions. This correlation is found by a consecutive spectral characterization of distinct proton beamlets emitted from different spatial target positions and under different angles. In case of a flat target and a perfectly round laser focal spot, the proton source is circular symmetric and each source point behaves similarly: the higher the proton energy the smaller the source size and the larger the emission angle for a similar source extension. Only the symmetry axis is unique; here all protons are emitted at 0
to the target normal.
Nakamura, Tatsufumi; Mima, Kunioki*; Ter-Avetisyan, S.*; Schnrer, M.*; Sokollic, T.*; Nickles, P.*; Sandner, W.*
Physical Review E, 77(3), p.036407_1 - 036407_5, 2008/03
Times Cited Count：13 Percentile：59.36(Physics, Fluids & Plasmas)The spatial dependence of proton acceleration at the rear surface of a target which is irradiated by high contrast and ultra-intense laser pulses is investigated. Lateral movement of proton acceleration position at the rear surface is observed, which is proofed by two-pinhole measurement which results in the observation of protons with narrow energy band. This drifting is uniquely observed when relativistic intensity laser pulses irradiate targets with small pre-plasma with oblique incidence, which is confirmed by 2D-PIC simulations. This proton acceleration scenario by the fast moving sheath field leads to the energy selection of accelerated protons as a function of observing position.
