The characteristics of a plasma formed by a focused ultrashort laser in atmospheric-pressure air are studied with linear and circular pulses. We show that the ionization threshold for circular pulses is 1.36 times higher than for that linear pulses. Using an intensified CCD camera, we study plasma emission over seven orders of magnitude in a dynamic range. In spite of possessing a lower total ion number, plasmas produced by circular pulses are found to be brighter visible-light emitters than those produced by linear pulses of the same energy. This indicates that circular pulses produce plasmas with more electron kinetic energy than linear pulses and that kinetic energy plays a role in the optical emission intensity. The presence of high energy electrons is verified by demonstrating that a high-ionization-potential gas can be made to radiate more brightly by the addition of a low-ionization-potential gas even though the second gas lowers the achievable focal intensity.

1.
I. Y.
Dodin
and
N. J.
Fisch
,
Phys. Plasmas
17
,
112113
(
2010
).
2.
P.
Pulsifer
,
J. P.
Apruzese
,
J.
Davis
, and
P.
Kepple
,
Phys. Rev. A
49
,
3958
3965
(
1994
).
3.
W. M.
Wood
,
C.
Siders
, and
M.
Downer
,
Phys. Rev. Lett.
67
,
3523
3526
(
1991
).
4.
N. H.
Burnett
and
P. B.
Corkum
,
J. Opt. Soc. Am. B
6
,
1195
1199
(
1989
).
5.
P. B.
Corkum
,
Phys. Rev. Lett.
71
,
1994
1997
(
1993
).
6.
T. E.
Glover
,
J. K.
Crane
,
M. D.
Perry
,
R. W.
Lee
, and
R. W.
Falcone
,
Phys. Rev. Lett.
75
,
445
448
(
1995
).
7.
T. E.
Glover
,
J. K.
Crane
,
M. D.
Perry
,
R. W.
Lee
, and
R. W.
Falcone
,
Phys. Rev. E
57
,
982
993
(
1998
).
8.
B.
He
and
T.-q.
Chang
,
Phys. Rev. E
71
,
066411
(
2005
).
9.
B. M.
Penetrante
and
J. N.
Bardsley
,
Phys. Rev. A
43
,
3100
3113
(
1991
).
10.
J.
Peyraud
and
N.
Peyraud
,
J. Appl. Phys.
43
,
2993
2996
(
1972
).
11.
P. H.
Bucksbaum
,
M.
Bashkansky
,
R. R.
Freeman
,
T. J.
McIlrath
, and
L. F.
DiMauro
,
Phys. Rev. Lett.
56
,
2590
2593
(
1986
).
12.
S. J.
McNaught
,
J. P.
Knauer
, and
D. D.
Meyerhofer
,
Phys. Rev. A
58
,
1399
1411
(
1998
).
13.
U.
Mohideen
,
M. H.
Sher
,
H. W. K.
Tom
,
G. D.
Aumiller
,
O. R.
Wood
 II
,
R. R.
Freeman
,
J.
Boker
, and
P. H.
Bucksbaum
,
Phys. Rev. Lett.
71
,
509
512
(
1993
).
14.
S. C.
Wilks
,
J. M.
Dawson
, and
W. B.
Mori
,
Phys. Rev. Lett.
61
,
337
340
(
1988
).
15.
P. M.
Bellan
,
Fundamentals of Plasma Physics
(
Cambridge University Press
,
New York
,
2006
).
16.
T. R.
Clark
and
H. M.
Milchberg
,
Phys. Rev. Lett.
78
,
2373
2376
(
1997
).
17.
T. R.
Clark
and
H. M.
Milchberg
,
Phys. Plasmas
7
,
2192
2197
(
2000
).
18.
P.
Volfbeyn
,
E.
Esarey
, and
W.
Leemans
,
Phys. Plasmas
6
,
2269
(
1999
).
19.
J.
Zweiback
and
T.
Ditmire
,
Phys. Plasmas
8
,
4545
(
2001
).
20.
V.
Bukin
,
S. V.
Garnov
,
A.
Malyutin
, and
V.
Strelkov
,
Quantum Electron.
37
,
961
(
2007
).
21.
R.
Rankin
,
C.
Capjack
,
N.
Burnett
, and
P. B.
Corkum
,
Opt. Lett.
16
,
835
837
(
1991
).
22.
A.
Couairon
and
A.
Mysyrowicz
,
Phys. Rep.
441
,
47
189
(
2007
).
23.
F.
Théberge
,
W.
Liu
,
P. T.
Simard
,
A.
Becker
, and
S. L.
Chin
,
Phys. Rev. E
74
,
036406
(
2006
).
24.
F.
Martin
,
R.
Mawassi
,
F.
Vidal
,
I.
Gallimberti
,
D.
Comtois
,
H.
Pepin
,
J.
Kieffer
, and
H.
Mercure
,
Appl. Spectrosc.
56
,
1444
1452
(
2002
).
25.
H. R.
Reiss
,
Phys. Rev. A
54
,
R1765
R1768
(
1996
).
26.
C.
Guo
and
G. N.
Gibson
,
Phys. Rev. A
63
,
040701
(
2001
).
27.
A.
Heins
and
C.
Guo
,
Opt. Lett.
37
,
599
601
(
2012
).
28.
A.
Heins
and
C. L.
Guo
,
Opt. Express
21
,
29401
29411
(
2013
).
29.
J.
Hermann
,
S.
Bruneau
, and
M.
Sentis
,
Thin Solid Films
453
,
377
382
(
2004
).
30.
J. B.
Hasted
,
Physics of Atomic Collisions
, 2nd ed. (
Elsevier
,
New York
,
1972
).
31.
S. S.
Harilal
,
B. E.
Brumfield
, and
M. C.
Phillips
,
Phys. Plasmas
22
,
063301
(
2015
).
32.
W.
Liu
and
S.
Chin
,
Opt. Express
13
,
5750
5755
(
2005
).
33.
J.
Schwarz
,
P.
Rambo
,
M.
Kimmel
, and
B.
Atherton
,
Opt. Express
20
,
8791
8803
(
2012
).
34.
P.
Whalen
,
J.
Moloney
, and
M.
Kolesik
,
Opt. Lett.
36
,
2542
(
2011
).
35.
M. D.
Feit
and
J. J. A.
Fleck
, “
Effect of refraction on spot-size dependence of laser-induced breakdown
,”
Appl. Phys. Lett.
24
,
169
172
(
1974
).
36.
M.
Mlejnek
,
E. M.
Wright
, and
J. V.
Moloney
,
Opt. Lett.
23
,
382
384
(
1998
).
37.
P.
Monot
,
T.
Auguste
,
L.
Lompré
,
G.
Mainfray
, and
C.
Manus
,
J. Opt. Soc. Am. B
9
,
1579
1584
(
1992
).
38.
A.
Iwasaki
,
N.
Aközbek
,
B.
Ferland
,
Q.
Luo
,
G.
Roy
,
C. M.
Bowden
, and
S. L.
Chin
,
Appl. Phys. B
76
,
231
236
(
2003
).
39.
S. P. L.
Blanc
and
R.
Sauerbrey
,
J. Opt. Soc. Am. B
13
,
72
88
(
1996
).
40.
A.
Becker
,
N.
Aközbek
,
K.
Vijayalakshmi
,
E.
Oral
,
C.
Bowden
, and
S.
Chin
,
Appl. Phys. B
73
,
287
290
(
2001
).
42.
S.
Rae
and
K.
Burnett
,
Phys. Rev. A
46
,
1084
(
1992
).
43.
S. C.
Rae
,
Opt. Commun.
104
,
330
335
(
1994
).
44.
E.
Yablonovitch
,
Phys. Rev. A
10
,
1888
1895
(
1974
).
45.
M.
Ammosov
,
N. B.
Delone
, and
V. P.
Krainov
,
Sov. Phys. JETP
64
,
1191
1194
(
1986
).
46.
A.
Perelomov
,
V.
Popov
, and
M.
Terent'ev
,
Sov. Phys. JETP
23
,
924
934
(
1966
).
47.
A.
Talebpour
,
J.
Yang
, and
S.
Chin
,
Opt. Commun.
163
,
29
32
(
1999
).
48.
P.
Béjot
,
J.
Kasparian
,
S.
Henin
,
V.
Loriot
,
T.
Vieillard
,
E.
Hertz
,
O.
Faucher
,
B.
Lavorel
, and
J.-P.
Wolf
,
Phys. Rev. Lett.
104
,
103903
(
2010
).
49.
N.
Aközbek
,
M.
Scalora
,
C.
Bowden
, and
S.
Chin
,
Opt. Commun.
191
,
353
362
(
2001
).
50.
A.
Couairon
,
E.
Gaižauskas
,
D.
Faccio
,
A.
Dubietis
, and
P.
Di Trapani
,
Phys. Rev. E
73
,
016608
(
2006
).
51.
A.
Couairon
,
J.
Biegert
,
C.
Hauri
,
W.
Kornelis
,
F.
Helbing
,
U.
Keller
, and
A.
Mysyrowicz
,
J. Mod. Opt.
53
,
75
85
(
2006
).
52.
B.
Alonso
,
Í. J.
Sola
,
J. S.
Román
,
Ó.
Varela
, and
L.
Roso
,
J. Opt. Soc. Am. B
28
,
1807
1816
(
2011
).
53.
A.
Kramida
,
Y.
Ralchenko
,
J.
Reader
, and
N. A.
Team
,
NIST Atomic Spectra Database (Version 5.0)
(
National Institute of Standards and Technology, Gaithersburg, MD
,
2012
), p.
2
.
You do not currently have access to this content.