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Dulat A, Aparajit C, Choudhary A, Lad AD, Ved YM, Paradkar BS, Ravindra Kumar G. Subpicosecond pre-plasma dynamics of a high contrast, ultraintense laser-solid target interaction. OPTICS LETTERS 2022; 47:5684-5687. [PMID: 37219303 DOI: 10.1364/ol.461452] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Accepted: 10/03/2022] [Indexed: 05/24/2023]
Abstract
Using the spectral interferometry technique, we measured subpicosecond time-resolved pre-plasma scale lengths and early expansion (<12 ps) of the plasma produced by a high intensity (6 × 1018 W/cm2) pulse with high contrast (109). We measured pre-plasma scale lengths in the range of 3-20 nm, before the arrival of the peak of the femtosecond pulse. This measurement plays a crucial role in understanding the mechanism of laser coupling its energy to hot electrons and is hence important for laser-driven ion acceleration and the fast ignition approach to fusion.
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Tata S, Mondal A, Sarkar S, Jha J, Ved Y, Lad AD, Colgan J, Pasley J, Krishnamurthy M. Recombination of Protons Accelerated by a High Intensity High Contrast Laser. PHYSICAL REVIEW LETTERS 2018; 121:134801. [PMID: 30312093 DOI: 10.1103/physrevlett.121.134801] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Indexed: 06/08/2023]
Abstract
Short pulse, high contrast, intense laser pulses incident onto a solid target are not known to generate fast neutral atoms. Experiments carried out to study the recombination of accelerated protons show a 200 times higher neutralization than expected. Fast neutral atoms can contribute to 80% of the fast particles at 10 keV, falling rapidly for higher energy. Conventional charge transfer and electron-ion recombination in a high density plasma plume near the target is unable to explain the neutralization. We present a model based on the copropagation of electrons and ions wherein recombination far away from the target surface accounts for the experimental measurements. A novel experimental verification of the model is also presented. This study provides insights into the closely linked dynamics of ions and electrons by which neutral atom formation is enhanced.
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Affiliation(s)
- Sheroy Tata
- Tata Institute of Fundamental Research, Mumbai 400 005, India
| | - Angana Mondal
- Tata Institute of Fundamental Research, Mumbai 400 005, India
| | - Soubhik Sarkar
- Tata Institute of Fundamental Research, Mumbai 400 005, India
| | - Jagannath Jha
- Tata Institute of Fundamental Research, Mumbai 400 005, India
| | - Yash Ved
- Tata Institute of Fundamental Research, Mumbai 400 005, India
| | - Amit D Lad
- Tata Institute of Fundamental Research, Mumbai 400 005, India
| | - James Colgan
- Los Alamos National Laboratory, New Mexico 87544, USA
| | - John Pasley
- York Plasma Institute, Department of Physics, University of York, York, YO10 5DD, United Kingdom
| | - M Krishnamurthy
- Tata Institute of Fundamental Research, Mumbai 400 005, India
- TIFR Centre for Interdisciplinary Sciences, Hyderabad 500 075, India
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Abstract
Recent advances in high-intensity laser-produced plasmas have demonstrated their potential as compact charge particle accelerators. Unlike conventional accelerators, transient quasi-static charge separation acceleration fields in laser produced plasmas are highly localized and orders of magnitude larger. Manipulating these ion accelerators, to convert the fast ions to neutral atoms with little change in momentum, transform these to a bright source of MeV atoms. The emittance of the neutral atom beam would be similar to that expected for an ion beam. Since intense laser-produced plasmas have been demonstrated to produce high-brightness-low-emittance beams, it is possible to envisage generation of high-flux, low-emittance, high energy neutral atom beams in length scales of less than a millimeter. Here, we show a scheme where more than 80% of the fast ions are reduced to energetic neutral atoms and demonstrate the feasibility of a high energy neutral atom accelerator that could significantly impact applications in neutral atom lithography and diagnostics.
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Contrasting levels of absorption of intense femtosecond laser pulses by solids. Sci Rep 2015; 5:17870. [PMID: 26648399 PMCID: PMC4673463 DOI: 10.1038/srep17870] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Accepted: 11/05/2015] [Indexed: 11/08/2022] Open
Abstract
The absorption of ultraintense, femtosecond laser pulses by a solid unleashes relativistic electrons, thereby creating a regime of relativistic optics. This has enabled exciting applications of relativistic particle beams and coherent X-ray radiation, and fundamental leaps in high energy density science and laboratory astrophysics. Obviously, central to these possibilities lies the basic problem of understanding and if possible, manipulating laser absorption. Surprisingly, the absorption of intense light largely remains an open question, despite the extensive variations in target and laser pulse structures. Moreover, there are only few experimental measurements of laser absorption carried out under very limited parameter ranges. Here we present an extensive investigation of absorption of intense 30 femtosecond laser pulses by solid metal targets. The study, performed under varying laser intensity and contrast ratio over four orders of magnitude, reveals a significant and non-intuitive dependence on these parameters. For contrast ratio of 10−9 and intensity of 2 × 1019 W cm−2, three observations are revealed: preferential acceleration of electrons along the laser axis, a ponderomotive scaling of electron temperature, and red shifting of emitted second-harmonic. These point towards the role of J × B absorption mechanism at relativistic intensity. The experimental results are supported by particle-in-cell simulations.
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Adak A, Robinson APL, Singh PK, Chatterjee G, Lad AD, Pasley J, Kumar GR. Terahertz acoustics in hot dense laser plasmas. PHYSICAL REVIEW LETTERS 2015; 114:115001. [PMID: 25839282 DOI: 10.1103/physrevlett.114.115001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Indexed: 06/04/2023]
Abstract
We present a hitherto unobserved facet of hydrodynamics, namely the generation of an ultrahigh frequency acoustic disturbance in the terahertz frequency range, whose origins are purely hydrodynamic in nature. The disturbance is caused by differential flow velocities down a density gradient in a plasma created by a 30 fs, 800 nm high-intensity laser (∼5×10(16) W/cm(2)). The picosecond scale observations enable us to capture these high frequency oscillations (1.9±0.6 THz) which are generated as a consequence of the rapid heating of the medium by the laser. Adoption of two complementary techniques, namely pump-probe reflectometry and pump-probe Doppler spectrometry provides unambiguous identification of this terahertz acoustic disturbance. Hydrodynamic simulations well reproduce the observations, offering insight into this process.
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Affiliation(s)
- Amitava Adak
- Tata Institute of Fundamental Research, Dr. Homi Bhabha Road, Colaba, Mumbai-400005, India
| | - A P L Robinson
- Central Laser Facility, Rutherford Appleton Laboratory, Chilton, Didcot OX10 0QX, United Kingdom
| | - Prashant Kumar Singh
- Tata Institute of Fundamental Research, Dr. Homi Bhabha Road, Colaba, Mumbai-400005, India
| | - Gourab Chatterjee
- Tata Institute of Fundamental Research, Dr. Homi Bhabha Road, Colaba, Mumbai-400005, India
| | - Amit D Lad
- Tata Institute of Fundamental Research, Dr. Homi Bhabha Road, Colaba, Mumbai-400005, India
| | - John Pasley
- Tata Institute of Fundamental Research, Dr. Homi Bhabha Road, Colaba, Mumbai-400005, India
- Central Laser Facility, Rutherford Appleton Laboratory, Chilton, Didcot OX10 0QX, United Kingdom
- York Plasma Institute, University of York, Heslington, York YO10 5DQ, United Kingdom
| | - G Ravindra Kumar
- Tata Institute of Fundamental Research, Dr. Homi Bhabha Road, Colaba, Mumbai-400005, India
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Peltz C, Varin C, Brabec T, Fennel T. Time-resolved x-ray imaging of anisotropic nanoplasma expansion. PHYSICAL REVIEW LETTERS 2014; 113:133401. [PMID: 25302885 DOI: 10.1103/physrevlett.113.133401] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2013] [Indexed: 06/04/2023]
Abstract
A complete time-resolved x-ray imaging experiment of laser heated solid-density hydrogen clusters is modeled by microscopic particle-in-cell simulations that account self-consistently for the microscopic cluster dynamics and electromagnetic wave evolution. A technique is developed to retrieve the anisotropic nanoplasma expansion from the elastic and inelastic x-ray scattering data. Our method takes advantage of the self-similar evolution of the nanoplasma density and enables us to make movies of ultrafast nanoplasma dynamics from pump-probe x-ray imaging experiments.
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Affiliation(s)
- Christian Peltz
- Institut für Physik, Universität Rostock, 18051 Rostock, Germany
| | - Charles Varin
- Department of Physics, University of Ottawa, 150 Louis Pasteur, Ontario K1N 6N5, Canada
| | - Thomas Brabec
- Department of Physics, University of Ottawa, 150 Louis Pasteur, Ontario K1N 6N5, Canada
| | - Thomas Fennel
- Institut für Physik, Universität Rostock, 18051 Rostock, Germany
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Chatterjee G, Singh PK, Adak A, Lad AD, Kumar GR. High-resolution measurements of the spatial and temporal evolution of megagauss magnetic fields created in intense short-pulse laser-plasma interactions. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2014; 85:013505. [PMID: 24517763 DOI: 10.1063/1.4861535] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
A pump-probe polarimetric technique is demonstrated, which provides a complete, temporally and spatially resolved mapping of the megagauss magnetic fields generated in intense short-pulse laser-plasma interactions. A normally incident time-delayed probe pulse reflected from its critical surface undergoes a change in its ellipticity according to the magneto-optic Cotton-Mouton effect due to the azimuthal nature of the ambient self-generated megagauss magnetic fields. The temporal resolution of the magnetic field mapping is typically of the order of the pulsewidth, limited by the laser intensity contrast, whereas a spatial resolution of a few μm is achieved by this optical technique. High-harmonics of the probe can be employed to penetrate deeper into the plasma to even near-solid densities. The spatial and temporal evolution of the megagauss magnetic fields at the target front as well as at the target rear are presented. The μm-scale resolution of the magnetic field mapping provides valuable information on the filamentary instabilities at the target front, whereas probing the target rear mirrors the highly complex fast electron transport in intense laser-plasma interactions.
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Affiliation(s)
- Gourab Chatterjee
- Tata Institute of Fundamental Research, 1 Homi Bhabha Road, Mumbai 400 005, India
| | - Prashant Kumar Singh
- Tata Institute of Fundamental Research, 1 Homi Bhabha Road, Mumbai 400 005, India
| | - Amitava Adak
- Tata Institute of Fundamental Research, 1 Homi Bhabha Road, Mumbai 400 005, India
| | - Amit D Lad
- Tata Institute of Fundamental Research, 1 Homi Bhabha Road, Mumbai 400 005, India
| | - G Ravindra Kumar
- Tata Institute of Fundamental Research, 1 Homi Bhabha Road, Mumbai 400 005, India
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Ping Y, Kemp AJ, Divol L, Key MH, Patel PK, Akli KU, Beg FN, Chawla S, Chen CD, Freeman RR, Hey D, Higginson DP, Jarrott LC, Kemp GE, Link A, McLean HS, Sawada H, Stephens RB, Turnbull D, Westover B, Wilks SC. Dynamics of relativistic laser-plasma interaction on solid targets. PHYSICAL REVIEW LETTERS 2012; 109:145006. [PMID: 23083255 DOI: 10.1103/physrevlett.109.145006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2011] [Indexed: 06/01/2023]
Abstract
A novel time-resolved diagnostic is used to record the critical surface motion during picosecond-scale relativistic laser interaction with a solid target. Single-shot measurements of the specular light show a redshift decreasing with time during the interaction, corresponding to a slowing-down of the hole boring process into overdense plasma. On-shot full characterization of the laser pulse enables simulations of the experiment without any free parameters. Two-dimensional particle-in-cell simulations yield redshifts that agree with the data, and support a simple explanation of the slowing-down of the critical surface based on momentum conservation between ions and reflected laser light.
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Affiliation(s)
- Y Ping
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
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Direct observation of turbulent magnetic fields in hot, dense laser produced plasmas. Proc Natl Acad Sci U S A 2012; 109:8011-5. [PMID: 22566660 DOI: 10.1073/pnas.1200753109] [Citation(s) in RCA: 129] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Turbulence in fluids is a ubiquitous, fascinating, and complex natural phenomenon that is not yet fully understood. Unraveling turbulence in high density, high temperature plasmas is an even bigger challenge because of the importance of electromagnetic forces and the typically violent environments. Fascinating and novel behavior of hot dense matter has so far been only indirectly inferred because of the enormous difficulties of making observations on such matter. Here, we present direct evidence of turbulence in giant magnetic fields created in an overdense, hot plasma by relativistic intensity (10(18) W/cm(2)) femtosecond laser pulses. We have obtained magneto-optic polarigrams at femtosecond time intervals, simultaneously with micrometer spatial resolution. The spatial profiles of the magnetic field show randomness and their k spectra exhibit a power law along with certain well defined peaks at scales shorter than skin depth. Detailed two-dimensional particle-in-cell simulations delineate the underlying interaction between forward currents of relativistic energy "hot" electrons created by the laser pulse and "cold" return currents of thermal electrons induced in the target. Our results are not only fundamentally interesting but should also arouse interest on the role of magnetic turbulence induced resistivity in the context of fast ignition of laser fusion, and the possibility of experimentally simulating such structures with respect to the sun and other stellar environments.
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