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Guided post-acceleration of laser-driven ions by a miniature modular structure.

Kar S, Ahmed H, Prasad R, Cerchez M, Brauckmann S, Aurand B, Cantono G, Hadjisolomou P, Lewis CL, Macchi A, Nersisyan G, Robinson AP, Schroer AM, Swantusch M, Zepf M, Willi O, Borghesi M - Nat Commun (2016)

Bottom Line: All-optical approaches to particle acceleration are currently attracting a significant research effort internationally.Here we introduce the concept of a versatile, miniature linear accelerating module, which, by employing laser-excited electromagnetic pulses directed along a helical path surrounding the laser-accelerated ion beams, addresses these shortcomings simultaneously.These results open up new opportunities for the development of extremely compact and cost-effective ion accelerators for both established and innovative applications.

View Article: PubMed Central - PubMed

Affiliation: School of Mathematics and Physics, Queen's University Belfast, Belfast BT7 1NN, UK.

ABSTRACT
All-optical approaches to particle acceleration are currently attracting a significant research effort internationally. Although characterized by exceptional transverse and longitudinal emittance, laser-driven ion beams currently have limitations in terms of peak ion energy, bandwidth of the energy spectrum and beam divergence. Here we introduce the concept of a versatile, miniature linear accelerating module, which, by employing laser-excited electromagnetic pulses directed along a helical path surrounding the laser-accelerated ion beams, addresses these shortcomings simultaneously. In a proof-of-principle experiment on a university-scale system, we demonstrate post-acceleration of laser-driven protons from a flat foil at a rate of 0.5 GeV m(-1), already beyond what can be sustained by conventional accelerator technologies, with dynamic beam collimation and energy selection. These results open up new opportunities for the development of extremely compact and cost-effective ion accelerators for both established and innovative applications.

No MeSH data available.


Effect of helical coil on TNSA beam.In comparison with the typical proton-beam profile obtained from a flat-foil target in the experiment shown in (a), (b) shows the beam profile obtained from the helical coil target. Au foils (10 μm thick) were used as the laser interaction target in both cases. The coil was made of 100 μm aluminium wire and had internal diameter, pitch and length of 0.7, ∼0.28 and 8.7 mm, respectively. The RCF stack was placed at 35 mm from the target. RCF images of 50 mm × 50 mm size are shown in a, which are five times larger compared with the RCF images shown in b (the black scale bar on the last piece of RCF in a and b correspond to 10 and 2 mm respectively), in order to account for the large divergence of the TNSA beam produced from the flat foils. The black-dashed circles on the first RCF layer for both a and b correspond to the projection of the exit ring of the coil on the RCF (∼2.8 mm diameter circle corresponding to ∼5° full cone angle). (c) shows the comparison between proton spectra from the reference flat-foil target and the helical coil target shown in b obtained by spectral deconvolution of the RCF signals described in refs 37, 38. The error bars were estimated from the possible error in dose conversion21 and uncertainties in background substraction. Since the flat-foil proton signal at ∼8 MeV was below the detection threshold, the solid black circle shows the upper bound for proton signal calculated by considering the detection threshold of the RCF (∼105 protons per MeV mm−2) and an overly generous beam size (10 mm diameter on the RCF, which is similar to the beam size at 6.6 MeV shown in a) for protons at that energy. (d) Three-dimensional profile of the pencil beam of protons obtained in the RCF corresponding to ∼9 MeV, where the inset shows the two-dimensional dose map of the central part of the beam. The white dashed circle in the insert represents the internal diameter of the helical coil.
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f3: Effect of helical coil on TNSA beam.In comparison with the typical proton-beam profile obtained from a flat-foil target in the experiment shown in (a), (b) shows the beam profile obtained from the helical coil target. Au foils (10 μm thick) were used as the laser interaction target in both cases. The coil was made of 100 μm aluminium wire and had internal diameter, pitch and length of 0.7, ∼0.28 and 8.7 mm, respectively. The RCF stack was placed at 35 mm from the target. RCF images of 50 mm × 50 mm size are shown in a, which are five times larger compared with the RCF images shown in b (the black scale bar on the last piece of RCF in a and b correspond to 10 and 2 mm respectively), in order to account for the large divergence of the TNSA beam produced from the flat foils. The black-dashed circles on the first RCF layer for both a and b correspond to the projection of the exit ring of the coil on the RCF (∼2.8 mm diameter circle corresponding to ∼5° full cone angle). (c) shows the comparison between proton spectra from the reference flat-foil target and the helical coil target shown in b obtained by spectral deconvolution of the RCF signals described in refs 37, 38. The error bars were estimated from the possible error in dose conversion21 and uncertainties in background substraction. Since the flat-foil proton signal at ∼8 MeV was below the detection threshold, the solid black circle shows the upper bound for proton signal calculated by considering the detection threshold of the RCF (∼105 protons per MeV mm−2) and an overly generous beam size (10 mm diameter on the RCF, which is similar to the beam size at 6.6 MeV shown in a) for protons at that energy. (d) Three-dimensional profile of the pencil beam of protons obtained in the RCF corresponding to ∼9 MeV, where the inset shows the two-dimensional dose map of the central part of the beam. The white dashed circle in the insert represents the internal diameter of the helical coil.

Mentions: Figure 3 shows proof-of-principle results using the helical coil target. In contrast to the typical divergent proton beam produced by a flat foil (Fig. 3a), the helical coil target (Fig. 3b) produced a highly collimated beam of protons of energy significantly higher than from a flat foil, as clearly observed in the RCF stack diagnostic. In the flat-foil proton spectrum shown in Fig. 3c, the proton number after 7 MeV falls below the detection threshold of the RCF—one can estimate 107 protons per MeV as an absolute maximum for 8 MeV protons, while assuming a very generous beam diameter (see caption of Fig. 3 for details). On the other hand, a spectral peak at ∼9 MeV (with ∼108 protons per MeV at the peak), with detectable RCF signal up to 10 MeV is observed in the case of Fig. 3b, providing a clear indication of an increase in proton energy resulting from the helical coil. Furthermore, as shown in Fig. 3d, the diameter of the focussed, narrow-band, 9 MeV beam at 35 mm from the target is less than the internal diameter of the coil, which indicates nearly collimated (<0.5° divergence) propagation of the protons after exiting the coil structure.


Guided post-acceleration of laser-driven ions by a miniature modular structure.

Kar S, Ahmed H, Prasad R, Cerchez M, Brauckmann S, Aurand B, Cantono G, Hadjisolomou P, Lewis CL, Macchi A, Nersisyan G, Robinson AP, Schroer AM, Swantusch M, Zepf M, Willi O, Borghesi M - Nat Commun (2016)

Effect of helical coil on TNSA beam.In comparison with the typical proton-beam profile obtained from a flat-foil target in the experiment shown in (a), (b) shows the beam profile obtained from the helical coil target. Au foils (10 μm thick) were used as the laser interaction target in both cases. The coil was made of 100 μm aluminium wire and had internal diameter, pitch and length of 0.7, ∼0.28 and 8.7 mm, respectively. The RCF stack was placed at 35 mm from the target. RCF images of 50 mm × 50 mm size are shown in a, which are five times larger compared with the RCF images shown in b (the black scale bar on the last piece of RCF in a and b correspond to 10 and 2 mm respectively), in order to account for the large divergence of the TNSA beam produced from the flat foils. The black-dashed circles on the first RCF layer for both a and b correspond to the projection of the exit ring of the coil on the RCF (∼2.8 mm diameter circle corresponding to ∼5° full cone angle). (c) shows the comparison between proton spectra from the reference flat-foil target and the helical coil target shown in b obtained by spectral deconvolution of the RCF signals described in refs 37, 38. The error bars were estimated from the possible error in dose conversion21 and uncertainties in background substraction. Since the flat-foil proton signal at ∼8 MeV was below the detection threshold, the solid black circle shows the upper bound for proton signal calculated by considering the detection threshold of the RCF (∼105 protons per MeV mm−2) and an overly generous beam size (10 mm diameter on the RCF, which is similar to the beam size at 6.6 MeV shown in a) for protons at that energy. (d) Three-dimensional profile of the pencil beam of protons obtained in the RCF corresponding to ∼9 MeV, where the inset shows the two-dimensional dose map of the central part of the beam. The white dashed circle in the insert represents the internal diameter of the helical coil.
© Copyright Policy - open-access
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4837447&req=5

f3: Effect of helical coil on TNSA beam.In comparison with the typical proton-beam profile obtained from a flat-foil target in the experiment shown in (a), (b) shows the beam profile obtained from the helical coil target. Au foils (10 μm thick) were used as the laser interaction target in both cases. The coil was made of 100 μm aluminium wire and had internal diameter, pitch and length of 0.7, ∼0.28 and 8.7 mm, respectively. The RCF stack was placed at 35 mm from the target. RCF images of 50 mm × 50 mm size are shown in a, which are five times larger compared with the RCF images shown in b (the black scale bar on the last piece of RCF in a and b correspond to 10 and 2 mm respectively), in order to account for the large divergence of the TNSA beam produced from the flat foils. The black-dashed circles on the first RCF layer for both a and b correspond to the projection of the exit ring of the coil on the RCF (∼2.8 mm diameter circle corresponding to ∼5° full cone angle). (c) shows the comparison between proton spectra from the reference flat-foil target and the helical coil target shown in b obtained by spectral deconvolution of the RCF signals described in refs 37, 38. The error bars were estimated from the possible error in dose conversion21 and uncertainties in background substraction. Since the flat-foil proton signal at ∼8 MeV was below the detection threshold, the solid black circle shows the upper bound for proton signal calculated by considering the detection threshold of the RCF (∼105 protons per MeV mm−2) and an overly generous beam size (10 mm diameter on the RCF, which is similar to the beam size at 6.6 MeV shown in a) for protons at that energy. (d) Three-dimensional profile of the pencil beam of protons obtained in the RCF corresponding to ∼9 MeV, where the inset shows the two-dimensional dose map of the central part of the beam. The white dashed circle in the insert represents the internal diameter of the helical coil.
Mentions: Figure 3 shows proof-of-principle results using the helical coil target. In contrast to the typical divergent proton beam produced by a flat foil (Fig. 3a), the helical coil target (Fig. 3b) produced a highly collimated beam of protons of energy significantly higher than from a flat foil, as clearly observed in the RCF stack diagnostic. In the flat-foil proton spectrum shown in Fig. 3c, the proton number after 7 MeV falls below the detection threshold of the RCF—one can estimate 107 protons per MeV as an absolute maximum for 8 MeV protons, while assuming a very generous beam diameter (see caption of Fig. 3 for details). On the other hand, a spectral peak at ∼9 MeV (with ∼108 protons per MeV at the peak), with detectable RCF signal up to 10 MeV is observed in the case of Fig. 3b, providing a clear indication of an increase in proton energy resulting from the helical coil. Furthermore, as shown in Fig. 3d, the diameter of the focussed, narrow-band, 9 MeV beam at 35 mm from the target is less than the internal diameter of the coil, which indicates nearly collimated (<0.5° divergence) propagation of the protons after exiting the coil structure.

Bottom Line: All-optical approaches to particle acceleration are currently attracting a significant research effort internationally.Here we introduce the concept of a versatile, miniature linear accelerating module, which, by employing laser-excited electromagnetic pulses directed along a helical path surrounding the laser-accelerated ion beams, addresses these shortcomings simultaneously.These results open up new opportunities for the development of extremely compact and cost-effective ion accelerators for both established and innovative applications.

View Article: PubMed Central - PubMed

Affiliation: School of Mathematics and Physics, Queen's University Belfast, Belfast BT7 1NN, UK.

ABSTRACT
All-optical approaches to particle acceleration are currently attracting a significant research effort internationally. Although characterized by exceptional transverse and longitudinal emittance, laser-driven ion beams currently have limitations in terms of peak ion energy, bandwidth of the energy spectrum and beam divergence. Here we introduce the concept of a versatile, miniature linear accelerating module, which, by employing laser-excited electromagnetic pulses directed along a helical path surrounding the laser-accelerated ion beams, addresses these shortcomings simultaneously. In a proof-of-principle experiment on a university-scale system, we demonstrate post-acceleration of laser-driven protons from a flat foil at a rate of 0.5 GeV m(-1), already beyond what can be sustained by conventional accelerator technologies, with dynamic beam collimation and energy selection. These results open up new opportunities for the development of extremely compact and cost-effective ion accelerators for both established and innovative applications.

No MeSH data available.