Guiding of high-intensity laser pulses in 100-mm-long hydrodynamic optical-field-ionized plasma channels

Editors' Suggestion
Open Access

Guiding of high-intensity laser pulses in 100-mm-long hydrodynamic optical-field-ionized plasma channels

A. Picksley, A. Alejo, J. Cowley, N. Bourgeois, L. Corner, L. Feder, J. Holloway, H. Jones, J. Jonnerby, H. M. Milchberg, L. R. Reid, A. J. Ross, R. Walczak, and S. M. Hooker

Phys. Rev. Accel. Beams 23, 081303 – Published 26 August 2020

Abstract

Hydrodynamic optically-field-ionized (HOFI) plasma channels up to 100 mm long are investigated. Optical guiding is demonstrated of laser pulses with a peak input intensity of $6 \times 10^{17} {W cm}^{- 2}$ through 100 mm long plasma channels with on-axis densities measured interferometrically to be as low as $n_{e 0} = (1.0 \pm 0.3) \times 10^{17} {cm}^{- 3}$ . Guiding is also observed at lower axial densities, which are inferred from magneto-hydrodynamic simulations to be approximately $7 \times 10^{16} {cm}^{- 3}$ . Measurements of the power attenuation lengths of the channels are shown to be in good agreement with those calculated from the measured transverse electron density profiles. To our knowledge, the plasma channels investigated in this work are the longest, and have the lowest on-axis density, of any free-standing waveguide demonstrated to guide laser pulses with intensities above $> 1 0^{17} {W cm}^{- 2}$ .

Received 29 May 2020
Accepted 13 August 2020

DOI:https://doi.org/10.1103/PhysRevAccelBeams.23.081303

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.

Published by the American Physical Society

Physics Subject Headings (PhySH)

High intensity laser-plasma interactions Laser driven electron acceleration Laser wakefield acceleration

Accelerators & Beams

Authors & Affiliations

A. Picksley¹, A. Alejo ¹, J. Cowley¹, N. Bourgeois², L. Corner ³, L. Feder⁴, J. Holloway¹, H. Jones ³, J. Jonnerby¹, H. M. Milchberg⁴, L. R. Reid ³, A. J. Ross ¹, R. Walczak¹, and S. M. Hooker ^1,*

¹John Adams Institute for Accelerator Science and Department of Physics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH, United Kingdom
²Central Laser Facility, STFC Rutherford Appleton Laboratory, Didcot OX11 0QX, United Kingdom
³Cockcroft Institute for Accelerator Science and Technology, School of Engineering, The Quadrangle, University of Liverpool, Brownlow Hill, Liverpool L69 3GH, United Kingdom
⁴Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland 20742, USA

^*simon.hooker@physics.ox.ac.uk

Article Text

Click to Expand

Supplemental Material

Click to Expand

References

Click to Expand

Issue

Vol. 23, Iss. 8 — August 2020

Reuse & Permissions

Author publication services for translation and copyediting assistance advertisement

Images

Figure 1
(a) Schematic diagram of the experiment layout. (b) Longitudinal variation of the transverse intensity profile of the axicon focus, measured in vacuo by a camera in the vacuum chamber. The red curve shows the axial intensity $I_{a x} (0)$ as a function of longitudinal position. (c) Time-integrated image of the visible plasma emission produced by the channel-forming beam focused into the gas cell at a fill pressure $P = 26 mbar$ . The scale visible at the bottom of the image is in cm. Note that the apparent decrease in plasma brightness near a scale reading of 2.5 cm arises from blackening of the cell window in that region, not from nonuniformity of the plasma.
Reuse & Permissions
Figure 2
(a) Deduced electron density profiles of HOFI channels for several initial fill pressures and $τ = 3.0 ns$ . For each plot the light bands show the standard deviation obtained from averaging approximately 10 shots. (b) Variation of the measured matched spot size $W_{M}$ with fill pressure.
Reuse & Permissions
Figure 3
Measured transverse fluence profiles of the guided beam at: (a) focus, in vacuum; (b) $z = 50 mm$ , in vacuum; (c) $z = 50 mm$ , for $P = 68 mbar$ and $τ = 3.0 ns$ ; (d) $z = 100 mm$ , for $P = 26 mbar$ and $τ = 2.7 ns$ . The transverse scale is the same for all plots, as indicated by the scale bar shown in (a). For plots (a), (c), and (d) the fluence is normalized to the peak value in that plot; the fluence scale for (b) is the same as in (a). Compared to (a), the fluence scales of (c) and (d) were increased by factors of approximately 4 and 7 respectively.
Reuse & Permissions
Figure 4
(a) Measured transverse fluence profile of the guided beam at the exit of a 50 mm long HOFI plasma channel formed at $τ = 3.0 ns$ and $P = (17 \pm 1) mbar$ . (b) Comparison of the on-axis electron density measured by interferometry (symbols) and that calculated by MHD simulations (solid line) for $τ = 3.0 ns$ and $P = 17 mbar$ . The axial electron density calculated by the MHD simulations for $P = 17 mbar$ is $7 \times 10^{16} {cm}^{- 3}$ .
Reuse & Permissions
Figure 5
Comparison of the measured and simulated energy transmission for plasma channels formed at $P = 26 mbar$ and $τ = 2.7 ns$ . The measured data is shown as open black circles, with error bars with a total length equal to one standard deviation. The dashed black line shows a fit of the function $T_{theory} (z) = T (0) \exp (- z / L_{att})$ to the experimental data. The open red circles show the calculated transmission for a Gaussian input beams with a spot size matched to the lowest-order mode of the channel. The solid red circles show the calculated energy transmission for an input beam with a transverse intensity profile equal to the experimentally measured profile [see Fig. 3]; the red shading shows the uncertainty in $T (z)$ arising from the uncertainties in the electron density profile. The red dash-dot line shows a fit of the function $T_{theory} (z)$ to the calculated transmission for the realistic input spot in the region $z > 50 mm$ .
Reuse & Permissions

Physical Review Accelerators and Beams