Making Measurements
Leaks
Using the LI-6400
4-45
(reference) was used for both sample and reference measurements. The re-
sults are plotted in Figure 4-10.
The diffusion effect
plotted in Figure 4-10 is equivalent to the
term in the model in Figure 4-9. Normalizing by the gradient
should make this data fall on one curve if the model is correct, and
it does to a reasonable degree (Figure 4-11). Curve fitting yields a diffusion
coefficient
k
of 0.46. (The easiest curve fit is to plot (1/
Flow
) on the X axis,
rather than
Flow
;
k
is then the slope of the line.) Note that the outliers tend to
be the data collected with the smallest gradient, so uncertainties in what the
true gradient was are largest.
Figure 4-10. CO
2
diffusion into a closed, empty LI-6400 chamber with black neo-
prene gaskets as a function of flow rate, for various reference concentrations C
r
.
C
a
(ambient CO
2
) was 400 µmol mol
-1
. Diffusion effects are highest at low flow
rates and large gradients. The lines in the figure connect data of common C
r
.
2
2
2
2
2
2
I
I
I
I
I
I
-15
-10
-5
0
5
0
100
200
300
400
500
600
C
s
- C
r
(µmol mol
-1
)
Flow Rate (µmol s
-1
)
0
250
600
2
1040
1570
I
2066
C
r
µmol mol
-1
CO
2
Diffusion Effect
C
a
= 400 µmol mol
-1
C
s
C
r
Ð
(
)
c
o
c
i
Ð
(
)
C
a
C
s
Ð
(
)
Содержание LI-6400
Страница 1: ...Using the LI 6400 Portable Photosynthesis System ...
Страница 15: ...Part I The Basics ...
Страница 16: ......
Страница 174: ...Making Measurements Answers to Questions 4 56 Using the LI 6400 4 ...
Страница 175: ...Part II Useful Details ...
Страница 176: ......
Страница 200: ...Standard Tools Power ON Hooks 5 24 Using the LI 6400 5 ...
Страница 214: ...Real Time Data Real Time Graphics 6 14 Using the LI 6400 6 ...
Страница 234: ...Environmental Control Light Control 7 20 Using the LI 6400 7 ...
Страница 244: ...Light Sensor Considerations Gallium Arsenide Phosphide GaAsP Sensor 8 10 Using the LI 6400 8 ...
Страница 288: ...Data Logging Making Your Own AutoPrograms 9 44 Using the LI 6400 9 ...
Страница 289: ...Part III Working With Files ...
Страница 290: ......
Страница 312: ...The LPL File System Troubleshooting 10 22 Using the LI 6400 10 ...
Страница 340: ...Downloading Files Using a Data Capture Program 11 28 Using the LI 6400 11 ...
Страница 375: ...Part IV Configuration Issues ...
Страница 376: ......
Страница 420: ...Defining User Variables Old Style vs New Style 15 18 Using the LI 6400 15 ...
Страница 454: ...Using an Energy Balance Further Reading 17 12 Using the LI 6400 17 ...
Страница 455: ...Part V Maintenance Troubleshooting ...
Страница 456: ......
Страница 572: ...Troubleshooting Useful Information 20 46 Using the LI 6400 20 ...
Страница 587: ...Diagnostics and Utilities Sys Utility Programs Using the LI 6400 21 15 EBVpd t C guess EBSatVap _EBvap_kPa ...
Страница 593: ...Part VI Programming ...
Страница 594: ......
Страница 622: ...Programming with LPL Compiler Directives 22 28 Using the LI 6400 22 ...
Страница 846: ...Index I 16 Using the LI 6400 ...