maximum and minimum absorption rate in the range of 10
18 W/cm
2 ~ 10
22 W/cm
2
with this conservation law. The absorption rate is not given by a line; however, it is
given by the upper and lower bands as seen in Fig. 7.21 [16], and the micro-physics
of absorption is still open question.
Let us briefly survey the theory giving Fig. 7.21. In the conservation law, a
stationary propagating hole-boring system is assumed to be seen in simple
evaluation of hole-boring velocity such as in [14]. The conservation law in [15] is
derived by stating with the kinetic description of hole-boring ions, bulk electrons,
and hot electrons. The hole pushing boundary is assumed the interface of solid and
vacuum as schematically shown in Fig. 7.22. This model is an extended RankineHugoniot relation for a stationary propagating piston front and rear. The incident
laser deposits its energy partially to the hot electrons and hole-boring electrons, and
the reflecting light also deposits momentum to the electrons. The hole-boring ions
are pulled by the stationary electrostatic field produced by both of the hole-boring
electrons and hot electrons. The leakage of the charge of the hot electrons is assumed
to be supplied by slowly drifting return current electrons.
After a precise mathematics, the following energy and momentum conservation
relations are derived [15]:
1.0
0.8
0.6
Simulation >15° incidence
Simulation oblique incidence
Experiment >15° incidence
Experiment oblique incidence
Experiment fit
f *
f *
0.4
Forbidden
Forbidden
I 1 λ 1
2 (W μm
2 cm
-2 )
Total absorption
0.2
0.0
10
19
10
20
10
21
10
22
Fig. 7.21 Comparison between absorption bounds and published data. The complete data set
compiled in [40] is reproduced here, spanning experimental and simulation data published over
the past two decades, across a variety of laser and plasma conditions. Dashed lines corresponding to
fits of selected experimental data are shown to guide the eye. Additional high-intensity simulation
data are reproduced from [17]. The upper limit on absorption f* is depicted in red and the lower
limit f * in blue, with forbidden regions indicated using shading. [Figure 3 in Ref. 16]
7.6 Absorption Efficiency Based on Conservation Laws
261
18 W/cm
2 ~ 10
22 W/cm
2
with this conservation law. The absorption rate is not given by a line; however, it is
given by the upper and lower bands as seen in Fig. 7.21 [16], and the micro-physics
of absorption is still open question.
Let us briefly survey the theory giving Fig. 7.21. In the conservation law, a
stationary propagating hole-boring system is assumed to be seen in simple
evaluation of hole-boring velocity such as in [14]. The conservation law in [15] is
derived by stating with the kinetic description of hole-boring ions, bulk electrons,
and hot electrons. The hole pushing boundary is assumed the interface of solid and
vacuum as schematically shown in Fig. 7.22. This model is an extended RankineHugoniot relation for a stationary propagating piston front and rear. The incident
laser deposits its energy partially to the hot electrons and hole-boring electrons, and
the reflecting light also deposits momentum to the electrons. The hole-boring ions
are pulled by the stationary electrostatic field produced by both of the hole-boring
electrons and hot electrons. The leakage of the charge of the hot electrons is assumed
to be supplied by slowly drifting return current electrons.
After a precise mathematics, the following energy and momentum conservation
relations are derived [15]:
1.0
0.8
0.6
Simulation >15° incidence
Simulation oblique incidence
Experiment >15° incidence
Experiment oblique incidence
Experiment fit
f *
f *
0.4
Forbidden
Forbidden
I 1 λ 1
2 (W μm
2 cm
-2 )
Total absorption
0.2
0.0
10
19
10
20
10
21
10
22
Fig. 7.21 Comparison between absorption bounds and published data. The complete data set
compiled in [40] is reproduced here, spanning experimental and simulation data published over
the past two decades, across a variety of laser and plasma conditions. Dashed lines corresponding to
fits of selected experimental data are shown to guide the eye. Additional high-intensity simulation
data are reproduced from [17]. The upper limit on absorption f* is depicted in red and the lower
limit f * in blue, with forbidden regions indicated using shading. [Figure 3 in Ref. 16]
7.6 Absorption Efficiency Based on Conservation Laws
261