We measure the emission of energetic electrons from the interaction between relativistic-intensity ultrashort laser pulses and a solid density plasma with a tunable density gradient scale length. We detect an electron beam that only appears with few-cycle pulses (<10 fs) and large plasma scale lengths (L > λ0). Numerical simulations, in agreement with the experiments, reveal that these electrons are accelerated by a laser wakefield. Plasma waves are indeed resonantly excited by the few-cycle laser pulses in the near-critical density region of the plasma. Electrons are then injected by ionization into the plasma waves and accelerated to relativistic energies. In this laser wakefield acceleration regime, the plasma waves are rotated by the plasma density gradient, which results in the electrons not being emitted in the same direction as the driving laser pulse.

1.
V.
Malka
,
J.
Faure
,
Y. A.
Gauduel
,
E.
Lefebvre
,
A.
Rousse
, and
K.
Ta Phuoc
, “
Principles and applications of compact laser–plasma accelerators
,”
Nat. Phys.
4
,
447
453
(
2008
).
2.
F.
Albert
and
A. G. R.
Thomas
, “
Applications of laser wakefield accelerator-based light sources
,”
Plasma Phys. Controlled Fusion
58
,
103001
(
2016
).
3.
O.
Lundh
,
J.
Lim
,
C.
Rechatin
,
L.
Ammoura
,
A.
Ben-Ismail
,
X.
Davoine
,
G.
Gallot
,
J.-P.
Goddet
,
E.
Lefebvre
,
V.
Malka
, and
J.
Faure
, “
Few femtosecond, few kiloampere electron bunch produced by a laser-plasma accelerator
,”
Nat. Phys.
7
,
219
(
2011
).
4.
J.
Faure
,
Y.
Glinec
,
A.
Pukhov
,
S.
Kiselev
,
S.
Gordienko
,
E.
Lefebvre
,
J.-P.
Rousseau
,
F.
Burgy
, and
V.
Malka
, “
A laser-plasma accelerator producing monoenergetic electron beams
,”
Nature
431
,
541
544
(
2004
).
5.
X.
Wang
,
R.
Zgadzaj
,
N.
Fazel
,
Z.
Li
,
S. A.
Yi
,
X.
Zhang
,
W.
Henderson
,
Y. Y.
Chang
,
R.
Korzekwa
,
H. E.
Tsai
,
C. H.
Pai
,
H.
Quevedo
,
G.
Dyer
,
E.
Gaul
,
M.
Martinez
,
A. C.
Bernstein
,
T.
Borger
,
M.
Spinks
,
M.
Donovan
,
V.
Khudik
,
G.
Shvets
,
T.
Ditmire
, and
M. C.
Downer
, “
Quasi-monoenergetic laser-plasma acceleration of electrons to 2 GeV
,”
Nat. Commun.
4
,
1988
(
2013
).
6.
W. P.
Leemans
,
A. J.
Gonsalves
,
H.-S.
Mao
,
K.
Nakamura
,
C.
Benedetti
,
C. B.
Schroeder
,
C.
Tóth
,
J.
Daniels
,
D. E.
Mittelberger
,
S. S.
Bulanov
,
J.-L.
Vay
,
C. G. R.
Geddes
, and
E.
Esarey
, “
Multi-GeV electron beams from capillary-discharge-guided subpetawatt laser pulses in the self-trapping regime
,”
Phys. Rev. Lett.
113
,
245002
(
2014
).
7.
D.
Guénot
,
D.
Gustas
,
A.
Vernier
,
B.
Beaurepaire
,
F.
Böhle
,
M.
Bocoum
,
M.
Lozano
,
A.
Jullien
,
R.
Lopez-Martens
,
A.
Lifschitz
, and
J.
Faure
, “
Relativistic electron beams driven by khz single-cycle light pulses
,”
Nat. Photonics
11
,
293
296
(
2017
).
8.
D.
Gustas
,
D.
Guénot
,
A.
Vernier
,
S.
Dutt
,
F.
Böhle
,
R.
Lopez-Martens
,
A.
Lifschitz
, and
J.
Faure
, “
High-charge relativistic electron bunches from a kHz laser-plasma accelerator
,”
Phys. Rev. Accel. Beams
21
,
013401
(
2018
).
9.
F.
Salehi
,
A. J.
Goers
,
G. A.
Hine
,
L.
Feder
,
D.
Kuk
,
B.
Miao
,
D.
Woodbury
,
K. Y.
Kim
, and
H. M.
Milchberg
, “
MeV electron acceleration at 1 kHz with <10 MJ laser pulses
,”
Opt. Lett.
42
,
215
218
(
2017
).
10.
E.
Esarey
,
C. B.
Schroeder
, and
W. P.
Leemans
, “
Physics of laser-driven plasma-based electron accelerators
,”
Rev. Mod. Phys.
81
,
1229
1285
(
2009
).
11.
A.
Macchi
,
M.
Borghesi
, and
M.
Passoni
, “
Ion acceleration by superintense laser-plasma interaction
,”
Rev. Mod. Phys.
85
,
751
793
(
2013
).
12.
C.
Thaury
and
F.
Quéré
, “
High-order harmonic and attosecond pulse generation on plasma mirrors: Basic mechanisms
,”
J. Phys. B: At., Mol. Opt. Phys.
43
,
213001
(
2010
).
13.
S. C.
Wilks
and
W. L.
Kruer
, “
Absorption of ultrashort, ultra-intense laser light by solids and overdense plasmas
,”
IEEE J. Quantum Electron.
33
,
1954
1968
(
1997
).
14.
Y.
Sentoku
,
V.
Bychenkov
,
K.
Flippo
,
A.
Maksimchuk
,
K.
Mima
,
G.
Mourou
,
Z.
Sheng
, and
D.
Umstadter
, “
High-energy ion generation in interaction. of short laser pulse with high-density plasma
,”
Appl. Phys. B
74
,
207
215
(
2002
).
15.
P.
McKenna
,
D.
Carroll
,
O.
Lundh
,
F.
Nürnberg
,
K.
Markey
,
S.
Bandyopadhyay
,
D.
Batani
,
R.
Evans
,
R.
Jafer
,
S.
Kar
 et al., “
Effects of front surface plasma expansion on proton acceleration in ultraintense laser irradiation of foil targets
,”
Laser Part. Beams
26
,
591
596
(
2008
).
16.
A. J.
Kemp
,
Y.
Sentoku
, and
M.
Tabak
, “
Hot-electron energy coupling in ultraintense laser-matter interaction
,”
Phys. Rev. E
79
,
066406
(
2009
).
17.
S.
Kahaly
,
S.
Monchocé
,
H.
Vincenti
,
T.
Dzelzainis
,
B.
Dromey
,
M.
Zepf
,
P.
Martin
, and
F.
Quéré
, “
Direct observation of density-gradient effects in harmonic generation from plasma mirrors
,”
Phys. Rev. Lett.
110
,
175001
(
2013
).
18.
G. G.
Scott
,
V.
Bagnoud
,
C.
Brabetz
,
R. J.
Clarke
,
J. S.
Green
,
R. I.
Heathcote
,
H. W.
Powell
,
B.
Zielbauer
,
T. D.
Arber
,
P.
McKenna
, and
D.
Neely
, “
Optimization of plasma mirror reflectivity and optical quality using double laser pulses
,”
New J. Phys.
17
,
033027
(
2015
).
19.
F.
Brunel
, “
Not-so-resonant, resonant absorption
,”
Phys. Rev. Lett.
59
,
52
55
(
1987
).
20.
A. A.
Gonoskov
,
A. V.
Korzhimanov
,
A. V.
Kim
,
M.
Marklund
, and
A. M.
Sergeev
, “
Ultrarelativistic nanoplasmonics as a route towards extreme-intensity attosecond pulses
,”
Phys. Rev. E
84
,
046403
(
2011
).
21.
M.
Thévenet
,
H.
Vincenti
, and
J.
Faure
, “
On the physics of electron ejection from laser-irradiated overdense plasmas
,”
Phys. Plasmas
23
,
063119
(
2016
).
22.
R.
Lichters
,
J.
Meyer-ter Vehn
, and
A.
Pukhov
, “
Short-pulse laser harmonics from oscillating plasma surfaces driven at relativistic intensity
,”
Phys. Plasmas
3
,
3425
3437
(
1996
).
23.
T.
Baeva
,
S.
Gordienko
, and
A.
Pukhov
, “
Theory of high-order harmonic generation in relativistic laser interaction with overdense plasma
,”
Phys. Rev. E
74
,
046404
(
2006
).
24.
M.
Thévenet
,
A.
Leblanc
,
S.
Kahaly
,
H.
Vincenti
,
A.
Vernier
,
F.
Quéré
, and
J.
Faure
, “
Vacuum laser acceleration of relativistic electrons using plasma mirror injectors
,”
Nat. Phys.
12
,
355
(
2016
).
25.
L.
Chopineau
,
A.
Leblanc
,
G.
Blaclard
,
A.
Denoeud
,
M.
Thévenet
,
J.-L.
Vay
,
G.
Bonnaud
,
P.
Martin
,
H.
Vincenti
, and
F.
Quéré
, “
Identification of coupling mechanisms between ultraintense laser light and dense plasmas
,” preprint arXiv:1809.03903 (
2018
); Phys. Rev. X (to be published).
26.
S.
Bastiani
,
A.
Rousse
,
C. Q. J.-P.
Geindre
,
P.
Audebert
,
G.
Harmoniaux
,
A.
Antonetti
, and
J.-C.
Gauthier
, “
Experimental study of the interaction of subpicosecond laser pulses with solid targets of varying initial scalelengths
,”
Phys. Rev. E
56
,
7179
7185
(
1997
).
27.
A. G.
Mordovanakis
,
J.
Easter
,
N.
Naumova
,
K.
Popov
,
P.-E.
Masson-Laborde
,
B.
Hou
,
I.
Sokolov
,
G.
Mourou
,
I. V.
Glazyrin
,
W.
Rozmus
,
V.
Bychenkov
,
J.
Nees
, and
K.
Krushelnick
, “
Quasimonoenergetic electron beams with relativistic energies and ultrashort duration from laser-solid interactions at 0.5 kHz
,”
Phys. Rev. Lett.
103
,
235001
(
2009
).
28.
Y.
Tian
,
J.
Liu
,
W.
Wang
,
C.
Wang
,
A.
Deng
,
C.
Xia
,
W.
Li
,
L.
Cao
,
H.
Lu
,
H.
Zhang
,
Y.
Xu
,
Y.
Leng
,
R.
Li
, and
Z.
Xu
, “
Electron emission at locked phases from the laser-driven surface plasma wave
,”
Phys. Rev. Lett.
109
,
115002
(
2012
).
29.
M.
Bocoum
,
M.
Thévenet
,
F.
Böhle
,
B.
Beaurepaire
,
A.
Vernier
,
A.
Jullien
,
J.
Faure
, and
R.
Lopez-Martens
, “
Anticorrelated emission of high harmonics and fast electron beams from plasma mirrors
,”
Phys. Rev. Lett.
116
,
185001
(
2016
).
30.
A.
Yogo
,
H.
Daido
,
S. V.
Bulanov
,
K.
Nemoto
,
Y.
Oishi
,
T.
Nayuki
,
T.
Fujii
,
K.
Ogura
,
S.
Orimo
,
A.
Sagisaka
,
J.-L.
Ma
,
T. Z.
Esirkepov
,
M.
Mori
,
M.
Nishiuchi
,
A. S.
Pirozhkov
,
S.
Nakamura
,
A.
Noda
,
H.
Nagatomo
,
T.
Kimura
, and
T.
Tajima
, “
Laser ion acceleration via control of the near-critical density target
,”
Phys. Rev. E
77
,
016401
(
2008
).
31.
A.
Henig
,
D.
Kiefer
,
K.
Markey
,
D. C.
Gautier
,
K. A.
Flippo
,
S.
Letzring
,
R. P.
Johnson
,
T.
Shimada
,
L.
Yin
,
B. J.
Albright
,
K. J.
Bowers
,
J. C.
Fernández
,
S. G.
Rykovanov
,
H.-C.
Wu
,
M.
Zepf
,
D.
Jung
,
V. K.
Liechtenstein
,
J.
Schreiber
,
D.
Habs
, and
B. M.
Hegelich
, “
Enhanced laser-driven ion acceleration in the relativistic transparency regime
,”
Phys. Rev. Lett.
103
,
045002
(
2009
).
32.
J. H.
Bin
,
W. J.
Ma
,
H. Y.
Wang
,
M. J. V.
Streeter
,
C.
Kreuzer
,
D.
Kiefer
,
M.
Yeung
,
S.
Cousens
,
P. S.
Foster
,
B.
Dromey
,
X. Q.
Yan
,
R.
Ramis
,
J.
Meyer-ter Vehn
,
M.
Zepf
, and
J.
Schreiber
, “
Ion acceleration using relativistic pulse shaping in near-critical-density plasmas
,”
Phys. Rev. Lett.
115
,
064801
(
2015
).
33.
H. W.
Powell
,
M.
King
,
R. J.
Gray
,
D. A.
MacLellan
,
B.
Gonzalez-Izquierdo
,
L. C.
Stockhausen
,
G.
Hicks
,
N. P.
Dover
,
D. R.
Rusby
,
D. C.
Carroll
,
H.
Padda
,
R.
Torres
,
S.
Kar
,
R. J.
Clarke
,
I. O.
Musgrave
,
Z.
Najmudin
,
M.
Borghesi
,
D.
Neely
, and
P.
McKenna
, “
Proton acceleration enhanced by a plasma jet in expanding foils undergoing relativistic transparency
,”
New J. Phys.
17
,
103033
(
2015
).
34.
Y. T.
Li
,
J.
Zhang
,
L. M.
Chen
,
Y. F.
Mu
,
T. J.
Liang
,
Z. Y.
Wei
,
Q. L.
Dong
,
Z. L.
Chen
,
H.
Teng
,
S. T.
Chun-Yu
,
W. M.
Jiang
,
Z. J.
Zheng
, and
X. W.
Tang
, “
Hot electrons in the interaction of femtosecond laser pulses with foil targets at a moderate laser intensity
,”
Phys. Rev. E
64
,
046407
(
2001
).
35.
D. F.
Cai
,
Y. Q.
Gu
,
Z. J.
Zheng
,
W. M.
Zhou
,
X. D.
Yang
,
C. Y.
Jiao
,
H.
Chen
,
T. S.
Wen
, and
S. T.
Chunyu
, “
Double-peak emission of hot electrons generated by femtosecond laser interaction with solid targets
,”
Phys. Rev. E
70
,
066410
(
2004
).
36.
G.
Malka
and
J. L.
Miquel
, “
Experimental confirmation of ponderomotive-force electrons produced by an ultrarelativistic laser pulse on a solid target
,”
Phys. Rev. Lett.
77
,
75
78
(
1996
).
37.
J.
Zhang
,
J.
Zhang
,
Z. M.
Sheng
,
Y. T.
Li
,
Y.
Qiu
,
Z.
Jin
, and
H.
Teng
, “
Emission direction of fast electrons in laser-solid interactions at intensities from the nonrelativistic to the relativistic
,”
Phys. Rev. E
69
,
046408
(
2004
).
38.
R.
Tommasini
,
E.
Fill
,
R.
Bruch
, and
G.
Pretzler
, “
Generation of monoenergetic ultrashort electron pulses from a fs laser plasma
,”
Appl. Phys. B
79
,
923
926
(
2004
).
39.
S.
Feister
,
D. R.
Austin
,
J. T.
Morrison
,
K. D.
Frische
,
C.
Orban
,
G.
Ngirmang
,
A.
Handler
,
J. R. H.
Smith
,
M.
Schillaci
,
J. A.
LaVerne
,
E. A.
Chowdhury
,
R. R.
Freeman
, and
W. M.
Roquemore
, “
Relativistic electron acceleration by MJ-class kHz lasers normally incident on liquid targets
,”
Opt. Express
25
,
18736
18750
(
2017
).
40.
Y. T.
Li
,
X. H.
Yuan
,
M. H.
Xu
,
Z. Y.
Zheng
,
Z. M.
Sheng
,
M.
Chen
,
Y. Y.
Ma
,
W. X.
Liang
,
Q. Z.
Yu
,
Y.
Zhang
,
F.
Liu
,
Z. H.
Wang
,
Z. Y.
Wei
,
W.
Zhao
,
Z.
Jin
, and
J.
Zhang
, “
Observation of a fast electron beam emitted along the surface of a target irradiated by intense femtosecond laser pulses
,”
Phys. Rev. Lett.
96
,
165003
(
2006
).
41.
T.
Toncian
,
C.
Wang
,
E.
McCary
,
A.
Meadows
,
A.
Arefiev
,
J.
Blakeney
,
K.
Serratto
,
D.
Kuk
,
C.
Chester
,
R.
Roycroft
,
L.
Gao
,
H.
Fu
,
X.
Yan
,
J.
Schreiber
,
I.
Pomerantz
,
A.
Bernstein
,
H.
Quevedo
,
G.
Dyer
,
T.
Ditmire
, and
B.
Hegelich
, “
Non-maxwellian electron distributions resulting from direct laser acceleration in near-critical plasmas
,”
Matter Radiat. Extremes
1
,
82
87
(
2016
).
42.
Y.
Ma
,
J.
Zhao
,
Y.
Li
,
D.
Li
,
L.
Chen
,
J.
Liu
,
S. J. D.
Dann
,
Y.
Ma
,
X.
Yang
,
Z.
Ge
,
Z.
Sheng
, and
J.
Zhang
, “
Ultrahigh-charge electron beams from laser-irradiated solid surface
,”
Proc. Natl. Acad. Sci.
115
,
6980
(
2018
).
43.
J. Y.
Mao
,
L. M.
Chen
,
K.
Huang
,
Y.
Ma
,
J. R.
Zhao
,
D. Z.
Li
,
W. C.
Yan
,
J. L.
Ma
,
M.
Aeschlimann
,
Z. Y.
Wei
, and
J.
Zhang
, “
Highly collimated monoenergetic target-surface electron acceleration in near-critical-density plasmas
,”
Appl. Phys. Lett.
106
,
131105
(
2015
).
44.
A.
Jullien
,
A.
Ricci
,
F.
Böhle
,
J.-P.
Rousseau
,
S.
Grabielle
,
N.
Forget
,
H.
Jacqmin
,
B.
Mercier
, and
R.
Lopez-Martens
, “
Carrier-envelope-phase stable, high-contrast, double chirped-pulse-amplification laser system
,”
Opt. Lett.
39
,
3774
3777
(
2014
).
45.
F.
Böhle
,
M.
Kretschmar
,
A.
Jullien
,
M.
Kovacs
,
M.
Miranda
,
R.
Romero
,
H.
Crespo
,
U.
Morgner
,
P.
Simon
,
R.
Lopez-Martens
, and
T.
Nagy
, “
Compression of CEP-stable multi-mJ laser pulses down to 4 fs in long hollow fibers
,”
Laser Phys. Lett.
11
,
095401
(
2014
).
46.
M.
Ouillé
,
F.
Böhle
,
A.
Vernier
,
M.
Bocoum
,
A.
Jullien
,
M.
Lozano
,
J.-P.
Rousseau
,
D.
Gustas
,
D.
Guénot
,
M.
Kovacs
,
A.
Blumenstein
,
P.
Simon
,
J.
Faure
,
S.
Haessler
,
T.
Nagy
, and
R.
Lopez-Martens
, “
Relativistic near-single-cycle light waves at 1 kHz
” (unpublished).
47.
M.
Bocoum
,
F.
Böhle
,
A.
Vernier
,
A.
Jullien
,
J.
Faure
, and
R.
Lopez-Martens
, “
Spatial-domain interferometer for measuring plasma mirror expansion
,”
Opt. Lett.
40
,
3009
3012
(
2015
).
48.
See http://warp.lbl.gov for more information concerning the code WARP.
49.
J.-L.
Vay
,
D. P.
Grote
,
R. H.
Cohen
, and
A.
Friedman
, “
Novel methods in the particle-in-cell accelerator code-framework Warp
,”
Comput. Sci. Discovery
5
,
014019
(
2012
).
50.
See https://www.picsar.net for more information concerning the high performance PICSAR library.
51.
H.
Vincenti
and
J.-L.
Vay
, “
Detailed analysis of the effects of stencil spatial variations with arbitrary high-order finite-difference Maxwell solver
,”
Comput. Phys. Commun.
200
,
147
167
(
2016
).
52.
H.
Vincenti
,
M.
Lobet
,
R.
Lehe
,
R.
Sasanka
, and
J.-L.
Vay
, “
An efficient and portable simd algorithm for charge/current deposition in particle-in-cell codes
,”
Comput. Phys. Commun.
210
,
145
154
(
2017
).
53.
H.
Vincenti
and
J.-L.
Vay
, “
Ultrahigh-order maxwell solver with extreme scalability for electromagnetic PIC simulations of plasmas
,”
Comput. Phys. Commun.
228
,
22
29
(
2018
).
54.
P.
Gibbon
,
Short Pulse Laser Interactions with Matter
(
World Scientific Publishing Company
,
2004
).
55.
J. P.
Colombier
,
P.
Combis
,
A.
Rosenfeld
,
I. V.
Hertel
,
E.
Audouard
, and
R.
Stoian
, “
Optimized energy coupling at ultrafast laser-irradiated metal surfaces by tailoring intensity envelopes: Consequences for material removal from Al samples
,”
Phys. Rev. B
74
,
224106
(
2006
).
56.
W. L.
Kruer
,
The Physics of Laser Plasma Interactions
(
Addison-Wesley
,
New York
,
1988
).
57.
C.
McGuffey
,
A. G. R.
Thomas
,
W.
Schumaker
,
T.
Matsuoka
,
V.
Chvykov
,
F. J.
Dollar
,
G.
Kalintchenko
,
V.
Yanovsky
,
A.
Maksimchuk
,
K.
Krushelnick
,
V. Y.
Bychenkov
,
I. V.
Glazyrin
, and
A. V.
Karpeev
, “
Ionization induced trapping in a laser wakefield accelerator
,”
Phys. Rev. Lett.
104
,
025004
(
2010
).
58.
A.
Pak
,
K. A.
Marsh
,
S. F.
Martins
,
W.
Lu
,
W. B.
Mori
, and
C.
Joshi
, “
Injection and trapping of tunnel-ionized electrons into laser-produced wakes
,”
Phys. Rev. Lett.
104
,
025003
(
2010
).

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