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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.


Related in: MedlinePlus

Helical coil working principle.(a) Schematic representation of the target designed for optimizing the beam parameters of laser-driven protons. In this configuration a helical coil, made of a metallic wire, is attached to the laser-irradiated thin foil at one end and grounded at the other end. The helical coil design guides the EM pulse carrying the neutralizing charge around the proton-beam axis and allows synchronizing its longitudinal propagation (that is, along z) with protons having a given energy within the beam. (b) Schematic representation snapshot showing the electric field configuration inside the coil. The red section of the coil represents the segment charged by the travelling pulse at a given moment of time, where the red arrows represent the electric field (E) lines originating from the coil, the black and blue arrows represent radial (Er) and longitudinal (Ez) components of the electric field, respectively. The length of the black and blue arrows represents the relative strength of the field at different locations. (c,d) Ez/(r=0) and Er/(z=0) profiles inside the coil at a given time, where z=0 corresponds to the location of the peak of charge density along the coil at that time. The field profiles are calculated by the subroutine that defines the input electric field configuration for particle tracing in the PTRACE simulation (see Methods). Dynamics are modelled using an asymmetric Gaussian pulse profile of 5 ps rise and 10 ps decay, as obtained in the experiment shown in Fig. 1e, travelling along a helical coil with the same dimensions as the one used in the experiment illustrated in Fig. 3.
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f2: Helical coil working principle.(a) Schematic representation of the target designed for optimizing the beam parameters of laser-driven protons. In this configuration a helical coil, made of a metallic wire, is attached to the laser-irradiated thin foil at one end and grounded at the other end. The helical coil design guides the EM pulse carrying the neutralizing charge around the proton-beam axis and allows synchronizing its longitudinal propagation (that is, along z) with protons having a given energy within the beam. (b) Schematic representation snapshot showing the electric field configuration inside the coil. The red section of the coil represents the segment charged by the travelling pulse at a given moment of time, where the red arrows represent the electric field (E) lines originating from the coil, the black and blue arrows represent radial (Er) and longitudinal (Ez) components of the electric field, respectively. The length of the black and blue arrows represents the relative strength of the field at different locations. (c,d) Ez/(r=0) and Er/(z=0) profiles inside the coil at a given time, where z=0 corresponds to the location of the peak of charge density along the coil at that time. The field profiles are calculated by the subroutine that defines the input electric field configuration for particle tracing in the PTRACE simulation (see Methods). Dynamics are modelled using an asymmetric Gaussian pulse profile of 5 ps rise and 10 ps decay, as obtained in the experiment shown in Fig. 1e, travelling along a helical coil with the same dimensions as the one used in the experiment illustrated in Fig. 3.

Mentions: Data presented in this paper were collected by using two different target geometries. The propagation of the ultra-short, high-amplitude EM pulse along a thin wire connected to the laser-irradiated target was initially characterized by using the target geometry shown by the schematic representation in Fig. 1a. In this case, the TNSA proton beam generated at the rear of the laser-irradiated target was used as a particle probe in a point-projection arrangement to obtain time resolved snapshots (see Methods section for additional information) of the pulse propagation along the wire (0.1 mm diameter Al wire), which was folded to a square wave pattern in front of and parallel to the interaction foil. The folded wire design was chosen to enable us to follow, in the diagnostic field of view, the pulse propagation along the wire over an extended distance (up to ∼35 mm). The second part of the experiment, which demonstrates the technique of using the EM pulse for control and optimization of the proton-beam parameters, was carried out by using a target that comprises a helical coil of suitable dimensions connected to the rear side of the laser irradiated foil, as shown in the Fig. 2a. The details of the target geometries and dimensions are discussed in the respective sections and figure captions.


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)

Helical coil working principle.(a) Schematic representation of the target designed for optimizing the beam parameters of laser-driven protons. In this configuration a helical coil, made of a metallic wire, is attached to the laser-irradiated thin foil at one end and grounded at the other end. The helical coil design guides the EM pulse carrying the neutralizing charge around the proton-beam axis and allows synchronizing its longitudinal propagation (that is, along z) with protons having a given energy within the beam. (b) Schematic representation snapshot showing the electric field configuration inside the coil. The red section of the coil represents the segment charged by the travelling pulse at a given moment of time, where the red arrows represent the electric field (E) lines originating from the coil, the black and blue arrows represent radial (Er) and longitudinal (Ez) components of the electric field, respectively. The length of the black and blue arrows represents the relative strength of the field at different locations. (c,d) Ez/(r=0) and Er/(z=0) profiles inside the coil at a given time, where z=0 corresponds to the location of the peak of charge density along the coil at that time. The field profiles are calculated by the subroutine that defines the input electric field configuration for particle tracing in the PTRACE simulation (see Methods). Dynamics are modelled using an asymmetric Gaussian pulse profile of 5 ps rise and 10 ps decay, as obtained in the experiment shown in Fig. 1e, travelling along a helical coil with the same dimensions as the one used in the experiment illustrated in Fig. 3.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4837447&req=5

f2: Helical coil working principle.(a) Schematic representation of the target designed for optimizing the beam parameters of laser-driven protons. In this configuration a helical coil, made of a metallic wire, is attached to the laser-irradiated thin foil at one end and grounded at the other end. The helical coil design guides the EM pulse carrying the neutralizing charge around the proton-beam axis and allows synchronizing its longitudinal propagation (that is, along z) with protons having a given energy within the beam. (b) Schematic representation snapshot showing the electric field configuration inside the coil. The red section of the coil represents the segment charged by the travelling pulse at a given moment of time, where the red arrows represent the electric field (E) lines originating from the coil, the black and blue arrows represent radial (Er) and longitudinal (Ez) components of the electric field, respectively. The length of the black and blue arrows represents the relative strength of the field at different locations. (c,d) Ez/(r=0) and Er/(z=0) profiles inside the coil at a given time, where z=0 corresponds to the location of the peak of charge density along the coil at that time. The field profiles are calculated by the subroutine that defines the input electric field configuration for particle tracing in the PTRACE simulation (see Methods). Dynamics are modelled using an asymmetric Gaussian pulse profile of 5 ps rise and 10 ps decay, as obtained in the experiment shown in Fig. 1e, travelling along a helical coil with the same dimensions as the one used in the experiment illustrated in Fig. 3.
Mentions: Data presented in this paper were collected by using two different target geometries. The propagation of the ultra-short, high-amplitude EM pulse along a thin wire connected to the laser-irradiated target was initially characterized by using the target geometry shown by the schematic representation in Fig. 1a. In this case, the TNSA proton beam generated at the rear of the laser-irradiated target was used as a particle probe in a point-projection arrangement to obtain time resolved snapshots (see Methods section for additional information) of the pulse propagation along the wire (0.1 mm diameter Al wire), which was folded to a square wave pattern in front of and parallel to the interaction foil. The folded wire design was chosen to enable us to follow, in the diagnostic field of view, the pulse propagation along the wire over an extended distance (up to ∼35 mm). The second part of the experiment, which demonstrates the technique of using the EM pulse for control and optimization of the proton-beam parameters, was carried out by using a target that comprises a helical coil of suitable dimensions connected to the rear side of the laser irradiated foil, as shown in the Fig. 2a. The details of the target geometries and dimensions are discussed in the respective sections and figure captions.

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.


Related in: MedlinePlus