Download Tomsk state university, Tomsk, Russia.

XXXIV conference on plasma physics and CF, February 12 – 16, 2007, Zvenigorod.
CALCULATION OF THE STATE LIFETIMES OF ATOMS IN AN ALTERNATING
ELECTRIC FIELD
Koryukina E.V.
Tomsk state university, Tomsk, Russia, e-mail: [email protected]
In this paper a calculation of state lifetimes of atoms in an alternating electric field was carried
out. Of special interest is a study of lifetimes of rare gas atoms because these gases are widely used
for plasma physics. In the given work a dependence of the state lifetimes on the frequency and
strength of a circular polarized electric field is investigated for He, Ne, Ar and Kr atoms. The
electric fields of such polarization are generated in high-frequency discharge and under laser
excitation.
A theoretical method considered in details in [1] was used for calculation of the wave functions,
shift and splitting of the energy levels in the electric field and the transition probabilities between
magnetic sublevels. In calculation of the wave functions all ns-, np-, nd- and nf-states with the
main quantum number n up to 10 were taken into account for He, Ne and Ar atoms. For a Kr atom
the energy levels with n up to 13 were taken into account. The calculations for a He atom were
carried out in the LS coupling scheme, the Jl coupling scheme was used for the rest rare gas atoms.
The J-state lifetime J of an atom in the electric field was calculated using the following formulas
[2]
3
4 JM
2
1
1
, J M 




A
(
JM

J
M
)

DJM , J M  ,
, A( J  J ) 
,
J 
A
(
JM

J
M
)

3
3c
(2 J  1) MM 
 A( J  J )
J
,ns
,ns
where AJM,JM is the transition probability between magnetic sublevels M and M, and D JM,JM is the
matrix element of the transition between magnetic sublevels.
It follows from the calculation results, that for the high-frequency discharge (the frequency of
the electric field =100MHz) the state lifetimes of all rare gas
atoms depend on the electric field strength as a cubic
36,48
1
polynomial. Under laser excitation, in particular, with frequency
36,45
(4 D2)
=241.813105MHz of the CO2-laser, the state lifetimes of rare
36,42
gas atoms depend on the electric field strength as a fifth-degree
36,39
polynomial. As an illustration, a dependence of the nd1D2-state
36,36
lifetimes on the electric field strength is showed for the He atom
36,33
0,0
0,2
0,4
0,6
0,8
1,0
in the high-frequency discharge. It is obvious, that the higher
73,5
73,0
the energy level from which the transition occurs, the more
72,5
sensitive the state lifetime will be to the electric field.
1
72,0
(5 D2)
The theoretical results obtained in this work can be used for
71,5
plasma
diagnostics and an explanation of the physical processes
71,0
70,5
taking place in the plasma induced by the circular polarized
70,0
electric field. These results also can be useful for the modelling
0,0 0,2 0,4 0,6 0,8 1,0
of new excitation and light sources.
F(kV/cm)
Литература
[1]. Koryukina E.V., J.Phys.D: Appl.Phys, 2005, 38, 3296-3303
[2]. Koryukina E.V., Proc. SPIE, 2006, 6263, 175-185