| 1. |
- Batani, D., et al.
(författare)
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Effects of laser prepulse on proton generation
- 2010
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. - : Elsevier BV. - 0168-9002. ; 620:1, s. 76-82
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Konferensbidrag (refereegranskat)abstract
- Low-intensity laser prepulse ( < 10(13) W/cm(2), ns duration) are a major issue in experiments on laser-generation of protons, often limiting the performances of proton sources produced by high-intensity lasers (approximate to 10(19) W/cm(2), ps or fs duration) Several effects are associated to the prepulse and are discussed in this contribution: i) Destruction of thin foil targets by the shock generated by the laser prepulse ii) Creation of preplasma on target front side affecting laser absorption iii) Deformation of target rear side iv) Whole displacement of thin foil targets affecting focusing condition In particular, we show that under oblique high-intensity irradiation and for low prepulse intensities, the proton beam is directed away from the target normal. Deviation is towards the laser forward direction, with an angle that increases with the level and duration of the ASE pedestal. Also, for a given laser pulse, beam deviation increases with proton energy. The observations are discussed in terms of Target Normal Sheath Acceleration, in combination with a laser-controllable shock wave locally deforming the target surface. (C) 2010 Elsevier B.V. All rights reserved.
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| 2. |
- Batani, D., et al.
(författare)
-
Effects of laser prepulse on proton generation
- 2010
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Ingår i: Radiation Effects and Defects in Solids. - : Informa UK Limited. - 1042-0150 .- 1029-4953. ; 165:6-10, s. 794-802
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Konferensbidrag (refereegranskat)abstract
- Prepulse is a major issue for laser generation of protons, often limiting the performances of laser sources. Here, we show the use of prepulse (1013W/cm2, ns duration) to actively manipulate the proton beam direction. Under oblique high-intensity irradiation (approximate to 1019W/cm2, ps duration) of the thin foil target, and for low prepulse intensities, the proton beam is directed away from the ounperturbedo target normal. Observations are discussed in terms of target normal sheath acceleration, in combination with a laser-controllable shock locally deforming the target surface.
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| 3. |
- Carroll, DC, et al.
(författare)
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Active manipulation of the spatial energy distribution of laser-accelerated proton beams
- 2007
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Ingår i: Physical Review E (Statistical, Nonlinear, and Soft Matter Physics). - 1539-3755. ; 76:065401(R), s. 1-065401
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Tidskriftsartikel (refereegranskat)abstract
- The spatial energy distributions of beams of protons accelerated by ultrahigh intensity (>10^19 W/cm2) picosecond laser pulse interactions with thin foil targets are investigated. Using separate, low intensity (<10^13 W/cm2) nanosecond laser pulses, focused onto the front surface of the target foil prior to the arrival of the high intensity pulse, it is demonstrated that the proton beam profile can be actively manipulated. In particular, results obtained with an annular intensity distribution at the focus of the low intensity beam are presented, showing smooth proton beams with a sharp circular boundary at all energies, which represents a significant improvement in the beam quality compared to irradiation with the picosecond beam alone.
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| 4. |
- Lindau, Filip, et al.
(författare)
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Laser-accelerated protons with energy dependent beam direction
- 2005
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Ingår i: Physical Review Letters. - 1079-7114. ; 95:175002, s. 1-175002
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Tidskriftsartikel (refereegranskat)abstract
- The spatial distribution of protons, accelerated by intense femtosecond laser pulses interacting with thin target foils under oblique irradiation are investigated. Under certain conditions, the proton beams are directed away from the target normal. This deviation is towards the laser forward direction, with an angle that increases with the level and duration of the amplified spontaneous emission pedestal before the main laser pulse. In addition, for a given laser pulse, this beam deviation increases with proton energy. The observations are discussed in terms of different electron acceleration mechanisms and target normal sheath acceleration, in combination with a laser-controllable shock wave locally deforming the target rear surface.
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| 5. |
- Lundh, Olle, et al.
(författare)
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Influence of shock waves on laser-driven proton acceleration
- 2007
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Ingår i: Physical Review E (Statistical, Nonlinear, and Soft Matter Physics). - 1539-3755. ; 76:2
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Tidskriftsartikel (refereegranskat)abstract
- The influence of shock waves, driven by amplified spontaneous emission (ASE), on laser-accelerated proton beams is investigated. A local deformation, produced by a cold shock wave launched by the ablation pressure of the ASE pedestal, can under oblique laser irradiation significantly direct the proton beam toward the laser axis. This can be understood in the frame of target normal sheath acceleration as proton emission from an area of the target where the local target normal is shifted toward the laser axis. Hydrodynamic simulations and experimental data show that there exists a window in laser and target parameter space where the target can be significantly deformed and yet facilitate efficient proton acceleration. The dependence of the magnitude of the deflection on target material, foil thickness, and ASE pedestal intensity and duration is experimentally investigated. The deflection angle is found to increase with increasing ASE intensity and duration and decrease with increasing target thickness. In a comparison between aluminum and copper target foils, aluminum is found to yield a larger proton beam deflection. An analytic model is successfully used to predict the proton emission direction.
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