-a diameter of lazer bunch on the lens,
- angular spread of lazer bunch before the lens(Ðiñ.2)
. Dependencies
h(F) on the formula (9)reduce on the drawing 3 at values
of parameters of experiment: =1.7ñì, =6
·1000 for different temperatures of liquid Ò
=100 , 80 , 20 ,P = 85âò. Dependencies
are build for the position of centre an êàóñòèêè
on surfaces of liquid. Dependency (9) allows to calculate
values of focal length ,under
which value - h - reaches a maximum value and value ,approximately
answer threshold of forming a channel:
On same Ðiñ.3 are brought experimental dependencies (dotted line).
As was
it already note, at the temperature of liquid Ò =100°C
practically the whole energy of radiating must go on the evaporation.
Naturally,that at the building of dependencies on the formula (9)(Ðiñ.3)
for this temperatures was use value
=1.
Dependency of
parameter from the temperature
of liquid is unknown.So corresponding values of parameter were defined
from the condition of best consent with the experiment.
I.e., as far as
from molded (10) is known dependency(T)
calculate as follows:
.
The Dependency(T)
normalize on the value
, which
we have take as 1,
is submit for the
Pic .4.
4. Discussing the results.
Discuss
a correlation of theoretical and experimental results. First, within the
framework of stated here simplify models is reached satisfactory consent
of theory and experiment on the nature of dependencies h(F)
and even on quantitative values (Pèñ
.3).
Secondly,
within the framework of this models is well explained dependency of depth
of channel from defocusing . In the experiment for all focal lengths and
temperatures a depth of channel depends only from the relations of values
an defocusing to the focal length F , i.e. moreover
value h , noticeably ñïàäàåò
at values |D
F/ F|@
0.15 . I.e.
in rough drawing near a diameter of focused bunch of radiating near a constrction
is changed under the law
, easy
value that values answer |D
F/ F|@
0.15
threshold of diameter of lazer bunch
d = 1.7
´
0.15 = 0.25sm.
Discuss now nature of unbalance of theoretical and ýêñïåðèìåíòàëüíûõ
results. In the first place follows to note high sensitivity of theoretical
dependencies to the value of parameter
, (but signifies and to values of share 
and
powers deliver 
on
the bottom).
In particular, 
and
presence 50% absorbing in the channel is capable to reduce a value
h on 35% . Possible exactly additional absorption a ferry,
sharply increase with increasing a depth of channel h
, brings about the restriction of depth of channel and difference
of theory and experiment for T =100 under greater values
of focal length F . Note , that influence of this factor
particularly greatly for lenses with the big focal length, for which even
small veriation of the value
bring about the observable âàðèàöèÿì
h , under which this is
reach:
For revision present models highly useful was measure absorption a pair,
which enough difficult correctly value theoreticaly , because of the profusion
of factors, on it affecting. Possible measurement scheme is a drive çîíäèðóþùåãî
lazer bunch along the surface of water through the formation a pair, expire
from the channel . The most essential divergence theoretical models with
the experimentals value is difference of ranges of existance vepour - gas
channel on the parameter F . According to theoretical
models greatly for forming a channel a value of focal length
powerfully depends (through
the dependency
) from the temperature of liquid. Then extrapolation of experimental dependencies
under different temperatures in area greater focal
distances
- (Pic .3) allows to assume,approximately
under all values of temperature equally, =
50sì . Note herewith , that predict by the theoretical model a de-emphasis
answer maximum h(F) under the fixed temperature, has
and in the experiment:
,though
offset of experimental maximums noticeably more weak theoretical . Expansion
of area of existance of channel on the parameter F
under low temperatures possible to explain as follows.
In theoretical
models , but more exactly at the building of dependencies (Pic.
3), was expect that parameter depends from the temperature
only. However from physicists of process is known that share of energy,
which disperses on the evaporation, depends on efficiency of a convection
motion . As far as of a convection moving a liquid most powerful
for big depth channels and practically are absent under h --->
0 , naturally consider that in areas of nondeep channels , when convection
does not to carry away from beneath the tip overheated liquid, share
eve x an
under Ò < 100°
tends to the
value T (100°
C ) . On edges
of area of existance of channel for this reason, under F< 5sì
and F>; 30sì , for low temperatures theoretical dependencies
on Ðiñ.3 give lowered
values. In particular, as far as on the threshold of arising a channel
of a convection motion practically is absence , possible expect that on
the threshold doe xs
not depend on temperatures, but this means an absence of dependencies or
highly weakenning dependency from the temperature of threshold of arising
a channel and F(limit.).
5.Conclusion.
Demonstrate
possibility to explain available experimental ïàðîãàçîâîãî
channel studies within the framework of simple models , based on that,
that in the field of äîíûøêà
channel power of return of vapours indemnifies a difference of curvature
of walls of channel and äîíûøêà,
i.e. power shallow stretching.
Received
evaluations of threshold of forming a channel, dependencies of its depth
from the focal length of lens F and dependencies of share
of the lazer energy x
, walking on the evaporation,
from the temperature of liquid.
Main òhåoretilaly
predictions models, which important check experiment
.
Predictions
models for 
require
adjustments, take ýêðàíèðîâêó
of radiating into account by vapours a water in the channel, which possible
do at presence experimental çíàåíèé
for the factor of absorbing fly from the crater a pair.
The thåîretical
dependency (Pic.
3) for low temperatures in the field of F<3;
>25ñì are distinguish from experimental dependencies of value
x from
the focal length under the fixed temperature.
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