LI-COR LI7200RS, Инструкция по эксплуатации

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accounted for in the equivalent pressure of P
ec
. A method of doing this (LI-COR
Application Note #116) is
8-16
.
P is pressure,
α
w
is the band broadening coefficient, and m
w
is the mole fraction of
water vapor. Mole density of H
2
O is given by
CO
2
Absorptance,
α
c
, is given by
8-17
where b
1
, b
2
, and b
3
are constants (
H
2
O SD1
,
SD2
, and
SD3
on the calibration
sheet) and V
c
is cooler voltage. Uncorrected absorptance,
α∗
c
, is given by
8-18
where A
c
and A
co
are raw signals from the CO
2
absorption and reference bands,
X
wc
is the cross sensitivity coefficient for water on CO
2
(
CO
2
XS
on the calibration
sheet), A
w
and A
wo
are the raw signals for the water absorption and reference
bands, Z
co
is the zeroing parameter (
CO2 Zero
), Z
c
is the temperature drift coef-
ficient (
CO
2
Z
on the calibration sheet), and T
block
is the block temperature.
Mole density of CO
2
,
ρ
c
, is given by
8-19
The coefficients for the 5th order polynomial f
c
( ) are given on the calibration
sheet. The polynomial has the form Ax + Bx
2
+ Cx
3
+ Dx
4
+ Ex
5
, where x =
α
c
S
c
/ P
ec
.
S
c
is the span parameter for CO
2
and P
ec
is equivalent pressure, and is the span-drift
corrected absorptance for CO
2
.
The value the LI-7550 needs to output for CO
2
absorptance is
α
w
(equation 8-17),
and for H
2
O absorptance is (equation 8-13). The span drift correction, implemented
in this manner, should leave the span setting algorithms unchanged.
Section 8. Theory of Operation
8-5 Equation Summary