# Coherent terahertz radiation emitted by wide-angle electron beams from a laser-wakefield accelerator

Research output: Chapter in Book/Report/Conference proceedingConference contribution book

### Abstract

Laser-wakefield accelerators generate femtosecond-duration electron bunches with energies from 10s of MeV to several GeV in millimetre distances by exploiting the large accelerating gradients created when a high-intensity laser pulse propagates in an underdense plasma. The process governing the formation of the accelerating structure ("bubble'') also causes the generation of sub-picosecond duration, 1-2~MeV nanocoulomb electron beams emitted obliquely into a hollow cone around the laser propagation axis. We present simulations showing that these wide-angle beams can be used to produce coherent transition radiation in the 0.1-5 THz frequency range with 10s~$\mu$J to mJ-level energy if passed through an inserted metal foil, or directly at the plasma-vacuum interface. We investigate how the properties of terahertz radiation change with foil size, position and orientation. The bunch length and size of wide-angle beams increase quickly as the electrons leave the accelerator, causing a shift of the radiation frequency peak from about 1 THz at a distance of 0.1~mm from the accelerator exit to 0.2 THz at 1~mm. If the foil size is reduced, for example to match the typical diameter of the plasma channel formed in a laser-wakefield accelerator, simulating the emission from the plasma-vacuum boundary, the low-frequency side of the spectrum is suppressed. The charge of wide-angle electron beams is expected to increase linearly with the laser intensity, with a corresponding quadratic increase of the terahertz radiation energy, potentially paving the way for mJ-level sources of coherent terahertz radiation.
Language English Proceedings Relativistic Plasma Waves and Particle Beams as Coherent and Incoherent Radiation Sources III Dino A. Jaroszynski, MinSup Hur Bellingham, WA 7 11036 9781510627383 10.1117/12.2523178 Published - 24 Apr 2019 SPIE Optics + Optoelectronics - Clarion Congress Hotel, Prague, Czech RepublicDuration: 1 Apr 2019 → 4 Apr 2019

### Publication series

Name Proceedings of SPIE SPIE 3 11036 0277-786X 1996-756X

### Conference

Conference SPIE Optics + Optoelectronics Czech Republic Prague 1/04/19 → 4/04/19

### Fingerprint

accelerators
electron beams
lasers
foils
metal foils
vacuum
high power lasers
hollow
cones
electrons
bubbles
frequency ranges
energy levels
low frequencies
propagation
energy
causes

### Keywords

• terahertz generation
• laser wakefield acceleration

### Cite this

Brunetti, E., Yang, X., & Jaroszynski, D. A. (2019). Coherent terahertz radiation emitted by wide-angle electron beams from a laser-wakefield accelerator. In D. A. Jaroszynski, & M. Hur (Eds.), Proceedings Relativistic Plasma Waves and Particle Beams as Coherent and Incoherent Radiation Sources III (Vol. 11036). [110360M] (Proceedings of SPIE; Vol. 11036, No. 3). Bellingham, WA. https://doi.org/10.1117/12.2523178
Brunetti, Enrico ; Yang, Xue ; Jaroszynski, Dino A. / Coherent terahertz radiation emitted by wide-angle electron beams from a laser-wakefield accelerator. Proceedings Relativistic Plasma Waves and Particle Beams as Coherent and Incoherent Radiation Sources III. editor / Dino A. Jaroszynski ; MinSup Hur. Vol. 11036 Bellingham, WA, 2019. (Proceedings of SPIE; 3).
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title = "Coherent terahertz radiation emitted by wide-angle electron beams from a laser-wakefield accelerator",
abstract = "Laser-wakefield accelerators generate femtosecond-duration electron bunches with energies from 10s of MeV to several GeV in millimetre distances by exploiting the large accelerating gradients created when a high-intensity laser pulse propagates in an underdense plasma. The process governing the formation of the accelerating structure ({"}bubble'') also causes the generation of sub-picosecond duration, 1-2~MeV nanocoulomb electron beams emitted obliquely into a hollow cone around the laser propagation axis. We present simulations showing that these wide-angle beams can be used to produce coherent transition radiation in the 0.1-5 THz frequency range with 10s~$\mu$J to mJ-level energy if passed through an inserted metal foil, or directly at the plasma-vacuum interface. We investigate how the properties of terahertz radiation change with foil size, position and orientation. The bunch length and size of wide-angle beams increase quickly as the electrons leave the accelerator, causing a shift of the radiation frequency peak from about 1 THz at a distance of 0.1~mm from the accelerator exit to 0.2 THz at 1~mm. If the foil size is reduced, for example to match the typical diameter of the plasma channel formed in a laser-wakefield accelerator, simulating the emission from the plasma-vacuum boundary, the low-frequency side of the spectrum is suppressed. The charge of wide-angle electron beams is expected to increase linearly with the laser intensity, with a corresponding quadratic increase of the terahertz radiation energy, potentially paving the way for mJ-level sources of coherent terahertz radiation.",
keywords = "terahertz generation, laser wakefield acceleration",
author = "Enrico Brunetti and Xue Yang and Jaroszynski, {Dino A.}",
note = "Copyright 2019 Society of Photo‑Optical Instrumentation Engineers (SPIE). One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this publication for a fee or for commercial purposes, and modification of the contents of the publication are prohibited.",
year = "2019",
month = "4",
day = "24",
doi = "10.1117/12.2523178",
language = "English",
isbn = "9781510627383",
volume = "11036",
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publisher = "SPIE",
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booktitle = "Proceedings Relativistic Plasma Waves and Particle Beams as Coherent and Incoherent Radiation Sources III",

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Brunetti, E, Yang, X & Jaroszynski, DA 2019, Coherent terahertz radiation emitted by wide-angle electron beams from a laser-wakefield accelerator. in DA Jaroszynski & M Hur (eds), Proceedings Relativistic Plasma Waves and Particle Beams as Coherent and Incoherent Radiation Sources III. vol. 11036, 110360M, Proceedings of SPIE, no. 3, vol. 11036, Bellingham, WA, SPIE Optics + Optoelectronics, Prague, Czech Republic, 1/04/19. https://doi.org/10.1117/12.2523178
Proceedings Relativistic Plasma Waves and Particle Beams as Coherent and Incoherent Radiation Sources III. ed. / Dino A. Jaroszynski; MinSup Hur. Vol. 11036 Bellingham, WA, 2019. 110360M (Proceedings of SPIE; Vol. 11036, No. 3).

Research output: Chapter in Book/Report/Conference proceedingConference contribution book

TY - GEN

T1 - Coherent terahertz radiation emitted by wide-angle electron beams from a laser-wakefield accelerator

AU - Brunetti, Enrico

AU - Yang, Xue

AU - Jaroszynski, Dino A.

N1 - Copyright 2019 Society of Photo‑Optical Instrumentation Engineers (SPIE). One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this publication for a fee or for commercial purposes, and modification of the contents of the publication are prohibited.

PY - 2019/4/24

Y1 - 2019/4/24

N2 - Laser-wakefield accelerators generate femtosecond-duration electron bunches with energies from 10s of MeV to several GeV in millimetre distances by exploiting the large accelerating gradients created when a high-intensity laser pulse propagates in an underdense plasma. The process governing the formation of the accelerating structure ("bubble'') also causes the generation of sub-picosecond duration, 1-2~MeV nanocoulomb electron beams emitted obliquely into a hollow cone around the laser propagation axis. We present simulations showing that these wide-angle beams can be used to produce coherent transition radiation in the 0.1-5 THz frequency range with 10s~$\mu$J to mJ-level energy if passed through an inserted metal foil, or directly at the plasma-vacuum interface. We investigate how the properties of terahertz radiation change with foil size, position and orientation. The bunch length and size of wide-angle beams increase quickly as the electrons leave the accelerator, causing a shift of the radiation frequency peak from about 1 THz at a distance of 0.1~mm from the accelerator exit to 0.2 THz at 1~mm. If the foil size is reduced, for example to match the typical diameter of the plasma channel formed in a laser-wakefield accelerator, simulating the emission from the plasma-vacuum boundary, the low-frequency side of the spectrum is suppressed. The charge of wide-angle electron beams is expected to increase linearly with the laser intensity, with a corresponding quadratic increase of the terahertz radiation energy, potentially paving the way for mJ-level sources of coherent terahertz radiation.

AB - Laser-wakefield accelerators generate femtosecond-duration electron bunches with energies from 10s of MeV to several GeV in millimetre distances by exploiting the large accelerating gradients created when a high-intensity laser pulse propagates in an underdense plasma. The process governing the formation of the accelerating structure ("bubble'') also causes the generation of sub-picosecond duration, 1-2~MeV nanocoulomb electron beams emitted obliquely into a hollow cone around the laser propagation axis. We present simulations showing that these wide-angle beams can be used to produce coherent transition radiation in the 0.1-5 THz frequency range with 10s~$\mu$J to mJ-level energy if passed through an inserted metal foil, or directly at the plasma-vacuum interface. We investigate how the properties of terahertz radiation change with foil size, position and orientation. The bunch length and size of wide-angle beams increase quickly as the electrons leave the accelerator, causing a shift of the radiation frequency peak from about 1 THz at a distance of 0.1~mm from the accelerator exit to 0.2 THz at 1~mm. If the foil size is reduced, for example to match the typical diameter of the plasma channel formed in a laser-wakefield accelerator, simulating the emission from the plasma-vacuum boundary, the low-frequency side of the spectrum is suppressed. The charge of wide-angle electron beams is expected to increase linearly with the laser intensity, with a corresponding quadratic increase of the terahertz radiation energy, potentially paving the way for mJ-level sources of coherent terahertz radiation.

KW - terahertz generation

KW - laser wakefield acceleration

U2 - 10.1117/12.2523178

DO - 10.1117/12.2523178

M3 - Conference contribution book

SN - 9781510627383

VL - 11036

T3 - Proceedings of SPIE

BT - Proceedings Relativistic Plasma Waves and Particle Beams as Coherent and Incoherent Radiation Sources III

A2 - Jaroszynski, Dino A.

A2 - Hur, MinSup

CY - Bellingham, WA

ER -

Brunetti E, Yang X, Jaroszynski DA. Coherent terahertz radiation emitted by wide-angle electron beams from a laser-wakefield accelerator. In Jaroszynski DA, Hur M, editors, Proceedings Relativistic Plasma Waves and Particle Beams as Coherent and Incoherent Radiation Sources III. Vol. 11036. Bellingham, WA. 2019. 110360M. (Proceedings of SPIE; 3). https://doi.org/10.1117/12.2523178