56 research outputs found
Efficient laser-driven proton acceleration from cylindrical and planar cryogenic hydrogen jets.
We report on recent experimental results deploying a continuous cryogenic hydrogen jet as a debris-free, renewable laser-driven source of pure proton beams generated at the 150 TW ultrashort pulse laser Draco. Efficient proton acceleration reaching cut-off energies of up to 20 MeV with particle numbers exceeding 109 particles per MeV per steradian is demonstrated, showing for the first time that the acceleration performance is comparable to solid foil targets with thicknesses in the micrometer range. Two different target geometries are presented and their proton beam deliverance characterized: cylindrical (∅ 5 μm) and planar (20 μm × 2 μm). In both cases typical Target Normal Sheath Acceleration emission patterns with exponential proton energy spectra are detected. Significantly higher proton numbers in laser-forward direction are observed when deploying the planar jet as compared to the cylindrical jet case. This is confirmed by two-dimensional Particle-in-Cell (2D3V PIC) simulations, which demonstrate that the planar jet proves favorable as its geometry leads to more optimized acceleration conditions
Observation of ultrafast solid-density plasma dynamics using femtosecond X-ray pulses from a free-electron laser
The complex physics of the interaction between short pulse high intensity
lasers and solids is so far hardly accessible by experiments. As a result of
missing experimental capabilities to probe the complex electron dynamics and
competing instabilities, this impedes the development of compact laser-based
next generation secondary radiation sources, e.g. for tumor therapy
[Bulanov2002,ledingham2007], laboratory-astrophysics
[Remington1999,Bulanov2015], and fusion [Tabak2014]. At present, the
fundamental plasma dynamics that occur at the nanometer and femtosecond scales
during the laser-solid interaction can only be elucidated by simulations. Here
we show experimentally that small angle X-ray scattering of femtosecond X-ray
free-electron laser pulses facilitates new capabilities for direct in-situ
characterization of intense short-pulse laser plasma interaction at solid
density that allows simultaneous nanometer spatial and femtosecond temporal
resolution, directly verifying numerical simulations of the electron density
dynamics during the short pulse high intensity laser irradiation of a solid
density target. For laser-driven grating targets, we measure the solid density
plasma expansion and observe the generation of a transient grating structure in
front of the pre-inscribed grating, due to plasma expansion, which is an
hitherto unknown effect. We expect that our results will pave the way for novel
time-resolved studies, guiding the development of future laser-driven particle
and photon sources from solid targets
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Observation of Ultrafast Solid-Density Plasma Dynamics Using Femtosecond X-Ray Pulses from a Free-Electron Laser
The complex physics of the interaction between short-pulse ultrahigh-intensity lasers and solids is so far difficult to access experimentally, and the development of compact laser-based next-generation secondary radiation sources, e.g., for tumor therapy, laboratory astrophysics, and fusion, is hindered by the lack of diagnostic capabilities to probe the complex electron dynamics and competing instabilities. At present, the fundamental plasma dynamics that occur at the nanometer and femtosecond scales during the laser-solid interaction can only be elucidated by simulations. Here we show experimentally that small-angle x-ray scattering of femtosecond x-ray free-electron laser pulses facilitates new capabilities for direct in situ characterization of intense short-pulse laser-plasma interactions at solid density that allows simultaneous nanometer spatial and femtosecond temporal resolution, directly verifying numerical simulations of the electron density dynamics during the short-pulse high-intensity laser irradiation of a solid density target. For laser-driven grating targets, we measure the solid density plasma expansion and observe the generation of a transient grating structure in front of the preinscribed grating, due to plasma expansion. The density maxima are interleaved, forming a double frequency grating in x-ray free-electron laser projection for a short time, which is a hitherto unknown effect. We expect that our results will pave the way for novel time-resolved studies, guiding the development of future laser-driven particle and photon sources from solid targets
Recommended from our members
Efficient laser-driven proton acceleration from cylindrical and planar cryogenic hydrogen jets
We report on recent experimental results deploying a continuous cryogenic hydrogen jet as a debris-free, renewable laser-driven source of pure proton beams generated at the 150 TW ultrashort pulse laser Draco. Efficient proton acceleration reaching cut-off energies of up to 20 MeV with particle numbers exceeding 109 particles per MeV per steradian is demonstrated, showing for the first time that the acceleration performance is comparable to solid foil targets with thicknesses in the micrometer range. Two different target geometries are presented and their proton beam deliverance characterized: cylindrical (∅ 5 μm) and planar (20 μm × 2 μm). In both cases typical Target Normal Sheath Acceleration emission patterns with exponential proton energy spectra are detected. Significantly higher proton numbers in laser-forward direction are observed when deploying the planar jet as compared to the cylindrical jet case. This is confirmed by two-dimensional Particle-in-Cell (2D3V PIC) simulations, which demonstrate that the planar jet proves favorable as its geometry leads to more optimized acceleration conditions
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