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Enhancing laser-driven proton acceleration by using micro-pillar arrays at high drive energy. Sci Rep 2017; 7:11366. [PMID: 28900164 PMCID: PMC5596005 DOI: 10.1038/s41598-017-11589-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Accepted: 08/23/2017] [Indexed: 11/09/2022] Open
Abstract
The interaction of micro- and nano-structured target surfaces with high-power laser pulses is being widely investigated for its unprecedented absorption efficiency. We have developed vertically aligned metallic micro-pillar arrays for laser-driven proton acceleration experiments. We demonstrate that such targets help strengthen interaction mechanisms when irradiated with high-energy-class laser pulses of intensities ~1017–18 W/cm2. In comparison with standard planar targets, we witness strongly enhanced hot-electron production and proton acceleration both in terms of maximum energies and particle numbers. Supporting our experimental results, two-dimensional particle-in-cell simulations show an increase in laser energy conversion into hot electrons, leading to stronger acceleration fields. This opens a window of opportunity for further improvements of laser-driven ion acceleration systems.
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Lübcke A, Andreev AA, Höhm S, Grunwald R, Ehrentraut L, Schnürer M. Prospects of target nanostructuring for laser proton acceleration. Sci Rep 2017; 7:44030. [PMID: 28290479 PMCID: PMC5349587 DOI: 10.1038/srep44030] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Accepted: 01/31/2017] [Indexed: 11/24/2022] Open
Abstract
In laser-based proton acceleration, nanostructured targets hold the promise to allow for significantly boosted proton energies due to strong increase of laser absorption. We used laser-induced periodic surface structures generated in-situ as a very fast and economic way to produce nanostructured targets capable of high-repetition rate applications. Both in experiment and theory, we investigate the impact of nanostructuring on the proton spectrum for different laser-plasma conditions. Our experimental data show that the nanostructures lead to a significant enhancement of absorption over the entire range of laser plasma conditions investigated. At conditions that do not allow for efficient laser absorption by plane targets, i.e. too steep plasma gradients, nanostructuring is found to significantly enhance the proton cutoff energy and conversion efficiency. In contrast, if the plasma gradient is optimized for laser absorption of the plane target, the nanostructure-induced absorption increase is not reflected in higher cutoff energies. Both, simulation and experiment point towards the energy transfer from the laser to the hot electrons as bottleneck.
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Affiliation(s)
- Andrea Lübcke
- Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie, Max-Born-Strasse 2a, 12489 Berlin, Germany
| | - Alexander A. Andreev
- Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie, Max-Born-Strasse 2a, 12489 Berlin, Germany
| | - Sandra Höhm
- Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie, Max-Born-Strasse 2a, 12489 Berlin, Germany
| | - Ruediger Grunwald
- Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie, Max-Born-Strasse 2a, 12489 Berlin, Germany
| | - Lutz Ehrentraut
- Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie, Max-Born-Strasse 2a, 12489 Berlin, Germany
| | - Matthias Schnürer
- Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie, Max-Born-Strasse 2a, 12489 Berlin, Germany
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Laser-Driven Ion Acceleration from Plasma Micro-Channel Targets. Sci Rep 2017; 7:42666. [PMID: 28218247 PMCID: PMC5316955 DOI: 10.1038/srep42666] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Accepted: 01/13/2017] [Indexed: 12/03/2022] Open
Abstract
Efficient energy boost of the laser-accelerated ions is critical for their applications in biomedical and hadron research. Achiev-able energies continue to rise, with currently highest energies, allowing access to medical therapy energy windows. Here, a new regime of simultaneous acceleration of ~100 MeV protons and multi-100 MeV carbon-ions from plasma micro-channel targets is proposed by using a ~1020 W/cm2 modest intensity laser pulse. It is found that two trains of overdense electron bunches are dragged out from the micro-channel and effectively accelerated by the longitudinal electric-field excited in the plasma channel. With the optimized channel size, these “superponderomotive” energetic electrons can be focused on the front surface of the attached plastic substrate. The much intense sheath electric-field is formed on the rear side, leading to up to ~10-fold ionic energy increase compared to the simple planar geometry. The analytical prediction of the optimal channel size and ion maximum energies is derived, which shows good agreement with the particle-in-cell simulations.
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Gopal R, Kumar R, Anand M, Kulkarni A, Singh DP, Krishnan SR, Sharma V, Krishnamurthy M. A source to deliver mesoscopic particles for laser plasma studies. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2017; 88:023301. [PMID: 28249480 DOI: 10.1063/1.4974973] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Intense ultrashort laser produced plasmas are a source for high brightness, short burst of X-rays, electrons, and high energy ions. Laser energy absorption and its disbursement strongly depend on the laser parameters and also on the initial size and shape of the target. The ability to change the shape, size, and material composition of the matter that absorbs light is of paramount importance not only from a fundamental physics point of view but also for potentially developing laser plasma sources tailored for specific applications. The idea of preparing mesoscopic particles of desired size/shape and suspending them in vacuum for laser plasma acceleration is a sparsely explored domain. In the following report we outline the development of a delivery mechanism of microparticles into an effusive jet in vacuum for laser plasma studies. We characterise the device in terms of particle density, particle size distribution, and duration of operation under conditions suitable for laser plasma studies. We also present the first results of x-ray emission from micro crystals of boric acid that extends to 100 keV even under relatively mild intensities of 1016 W/cm2.
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Affiliation(s)
- R Gopal
- Tata Institute of Fundamental Research, 21, Brundhavan Colony, Hyderabad 500075, India
| | - R Kumar
- Department of Physics, Indian Institute of Technology Hyderabad, Kandi, Sangareddy 502285, India
| | - M Anand
- Tata Institute of Fundamental Research, 21, Brundhavan Colony, Hyderabad 500075, India
| | - A Kulkarni
- Tata Institute of Fundamental Research, 21, Brundhavan Colony, Hyderabad 500075, India
| | - D P Singh
- Tata Institute of Fundamental Research, 21, Brundhavan Colony, Hyderabad 500075, India
| | - S R Krishnan
- Department of Physics, Indian Institute of Technology Madras, Chennai 600036, India
| | - V Sharma
- Department of Physics, Indian Institute of Technology Hyderabad, Kandi, Sangareddy 502285, India
| | - M Krishnamurthy
- Tata Institute of Fundamental Research, 21, Brundhavan Colony, Hyderabad 500075, India
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Dalui M, Wang WM, Trivikram TM, Sarkar S, Tata S, Jha J, Ayyub P, Sheng ZM, Krishnamurthy M. Preferential enhancement of laser-driven carbon ion acceleration from optimized nanostructured surfaces. Sci Rep 2015; 5:11930. [PMID: 26153048 PMCID: PMC4495568 DOI: 10.1038/srep11930] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Accepted: 04/28/2015] [Indexed: 11/20/2022] Open
Abstract
High-intensity ultrashort laser pulses focused on metal targets readily generate hot dense plasmas which accelerate ions efficiently and can pave way to compact table-top accelerators. Laser-driven ion acceleration studies predominantly focus on protons, which experience the maximum acceleration owing to their highest charge-to-mass ratio. The possibility of tailoring such schemes for the preferential acceleration of a particular ion species is very much desired but has hardly been explored. Here, we present an experimental demonstration of how the nanostructuring of a copper target can be optimized for enhanced carbon ion acceleration over protons or Cu-ions. Specifically, a thin (≈0.25 μm) layer of 25–30 nm diameter Cu nanoparticles, sputter-deposited on a polished Cu-substrate, enhances the carbon ion energy by about 10-fold at a laser intensity of 1.2×1018 W/cm2. However, particles smaller than 20 nm have an adverse effect on the ion acceleration. Particle-in-cell simulations provide definite pointers regarding the size of nanoparticles necessary for maximizing the ion acceleration. The inherent contrast of the laser pulse is found to play an important role in the species selective ion acceleration.
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Affiliation(s)
- Malay Dalui
- Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400 005, India
| | - W-M Wang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.,Forschungszentrum Jülich GmbH, Institute for Advanced Simulation, Jülich Supercomputing Centre, D-52425 Jülich, Germany.,IFSA Collaborative Innovation Center, Shanghai Jiao Tong University, Shanghai 200240, China
| | - T Madhu Trivikram
- Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400 005, India
| | - Subhrangsu Sarkar
- Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400 005, India
| | - Sheroy Tata
- Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400 005, India
| | - J Jha
- Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400 005, India
| | - P Ayyub
- Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400 005, India
| | - Z M Sheng
- IFSA Collaborative Innovation Center, Shanghai Jiao Tong University, Shanghai 200240, China.,SUPA, Department of Physics, University of Strathclyde, Glasgow G4 0NG, United Kingdom.,Key Laboratory for Laser Plasmas (MoE), Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
| | - M Krishnamurthy
- Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400 005, India.,TIFR Centre for Interdisciplinary Sciences, 21 Brundavan Colony, Narsingi, Hyderabad 500075, India
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