Instrumentation & Measurement Magazine 24-9 - 38

temperatures. It was only
possible to test two connectors
out of eight because
of the small geometry of
the support inserted in the
tank. An optical fiber with
an FBG was connected on
both FC/APC connectors
to be tested on flange n°1.
The connection of the box
to the optical interrogator
was done with a Fischer FiberOptic
4 channels cable,
as shown in Fig. 5.
The mechanism containing
the optical feedthrough was plunged in the tank, and then
it was sealed. After that, the tank was purged to remove air and
it was filled with liquid He. It was possible to track the Bragg
peak during the cooling down to 4 K in both optical channels.
Application of Strain Measurements
in High-field and Low-temperature
Environments with Long Models
After the study, realized thanks to the mirror instrumentation
on the short models LTS magnets, the coils of the long models
LTS magnets (7.15 m) were only equipped with optical strain
gauges. FBGs were bonded on the coils both longitudinally
and azimuthally at three different locations; lead end (LE),
middle (MI) and return end (RE). Thus, each coil was equipped
with six FBGs. The optical feedthrough box was installed close
to the lead end of the magnet.
The FBG signals were monitored during cool-down to 1.9 K
and the temperature was measured with a temperature sensor
installed close to the magnet cold mass. Fig. 6 shows the
temperature profile and azimuthal strain measurements (not
compensated thermally) observed on the four coils (CO110,
CO111, CO112 and, CO113) of the magnet at the three different
locations (LE, MI and, RE) during cool-down.
The thermal compensation on the FBG signals at 1.9 K is
done once the magnet's temperature is stable and before beginning
the powering tests at 1.9 K. The calibration of the thermal
compensation is done thanks to the results provided in [5],
where the apparent strain of optical sensors based on FBG were
measured. Fig. 7 shows examples of strain profiles measured on
one coil (Coil 113) of the long LTS magnet during two powering
tests up to 15 kA at 1.9 K. It was possible to measure the strain
profiles of the coils during different current ramps trainings.
Table 1 - Statistical study on the agreement between electrical and optical sensor
bonded on coils of different short model LTS magnets (azimuthal direction)
LTS Magnet
Short model 1
Short model 2
Short model 3
Magnet's coil
Coil 1
Coil 2
Coil 3
Coil 1
Coil 2
Coil 1
Number of powering
tests used in the
statistical study
25
25
25
42
42
51
Mean slope
(with std. deviation)
0.99 ± 0.04
1.02 ± 0.02
1.01 ± 0.02
0.92 ± 0.03
1.07 ± 0.03
0.99 ± 0.04
Fig. 7. Examples of strain profile measured on one coil (Coil 113) of the long LTS magnet during two different powering tests at 1.9 K.
38
IEEE Instrumentation & Measurement Magazine
December 2021

Instrumentation & Measurement Magazine 24-9

Table of Contents for the Digital Edition of Instrumentation & Measurement Magazine 24-9

Instrumentation & Measurement Magazine 24-9 - Cover1
Instrumentation & Measurement Magazine 24-9 - Cover2
Instrumentation & Measurement Magazine 24-9 - 1
Instrumentation & Measurement Magazine 24-9 - 2
Instrumentation & Measurement Magazine 24-9 - 3
Instrumentation & Measurement Magazine 24-9 - 4
Instrumentation & Measurement Magazine 24-9 - 5
Instrumentation & Measurement Magazine 24-9 - 6
Instrumentation & Measurement Magazine 24-9 - 7
Instrumentation & Measurement Magazine 24-9 - 8
Instrumentation & Measurement Magazine 24-9 - 9
Instrumentation & Measurement Magazine 24-9 - 10
Instrumentation & Measurement Magazine 24-9 - 11
Instrumentation & Measurement Magazine 24-9 - 12
Instrumentation & Measurement Magazine 24-9 - 13
Instrumentation & Measurement Magazine 24-9 - 14
Instrumentation & Measurement Magazine 24-9 - 15
Instrumentation & Measurement Magazine 24-9 - 16
Instrumentation & Measurement Magazine 24-9 - 17
Instrumentation & Measurement Magazine 24-9 - 18
Instrumentation & Measurement Magazine 24-9 - 19
Instrumentation & Measurement Magazine 24-9 - 20
Instrumentation & Measurement Magazine 24-9 - 21
Instrumentation & Measurement Magazine 24-9 - 22
Instrumentation & Measurement Magazine 24-9 - 23
Instrumentation & Measurement Magazine 24-9 - 24
Instrumentation & Measurement Magazine 24-9 - 25
Instrumentation & Measurement Magazine 24-9 - 26
Instrumentation & Measurement Magazine 24-9 - 27
Instrumentation & Measurement Magazine 24-9 - 28
Instrumentation & Measurement Magazine 24-9 - 29
Instrumentation & Measurement Magazine 24-9 - 30
Instrumentation & Measurement Magazine 24-9 - 31
Instrumentation & Measurement Magazine 24-9 - 32
Instrumentation & Measurement Magazine 24-9 - 33
Instrumentation & Measurement Magazine 24-9 - 34
Instrumentation & Measurement Magazine 24-9 - 35
Instrumentation & Measurement Magazine 24-9 - 36
Instrumentation & Measurement Magazine 24-9 - 37
Instrumentation & Measurement Magazine 24-9 - 38
Instrumentation & Measurement Magazine 24-9 - 39
Instrumentation & Measurement Magazine 24-9 - 40
Instrumentation & Measurement Magazine 24-9 - 41
Instrumentation & Measurement Magazine 24-9 - 42
Instrumentation & Measurement Magazine 24-9 - 43
Instrumentation & Measurement Magazine 24-9 - 44
Instrumentation & Measurement Magazine 24-9 - 45
Instrumentation & Measurement Magazine 24-9 - 46
Instrumentation & Measurement Magazine 24-9 - 47
Instrumentation & Measurement Magazine 24-9 - 48
Instrumentation & Measurement Magazine 24-9 - 49
Instrumentation & Measurement Magazine 24-9 - 50
Instrumentation & Measurement Magazine 24-9 - 51
Instrumentation & Measurement Magazine 24-9 - 52
Instrumentation & Measurement Magazine 24-9 - 53
Instrumentation & Measurement Magazine 24-9 - 54
Instrumentation & Measurement Magazine 24-9 - 55
Instrumentation & Measurement Magazine 24-9 - 56
Instrumentation & Measurement Magazine 24-9 - 57
Instrumentation & Measurement Magazine 24-9 - 58
Instrumentation & Measurement Magazine 24-9 - 59
Instrumentation & Measurement Magazine 24-9 - 60
Instrumentation & Measurement Magazine 24-9 - 61
Instrumentation & Measurement Magazine 24-9 - 62
Instrumentation & Measurement Magazine 24-9 - 63
Instrumentation & Measurement Magazine 24-9 - 64
Instrumentation & Measurement Magazine 24-9 - 65
Instrumentation & Measurement Magazine 24-9 - 66
Instrumentation & Measurement Magazine 24-9 - 67
Instrumentation & Measurement Magazine 24-9 - 68
Instrumentation & Measurement Magazine 24-9 - 69
Instrumentation & Measurement Magazine 24-9 - 70
Instrumentation & Measurement Magazine 24-9 - 71
Instrumentation & Measurement Magazine 24-9 - 72
Instrumentation & Measurement Magazine 24-9 - 73
Instrumentation & Measurement Magazine 24-9 - 74
Instrumentation & Measurement Magazine 24-9 - 75
Instrumentation & Measurement Magazine 24-9 - 76
Instrumentation & Measurement Magazine 24-9 - 77
Instrumentation & Measurement Magazine 24-9 - 78
Instrumentation & Measurement Magazine 24-9 - 79
Instrumentation & Measurement Magazine 24-9 - 80
Instrumentation & Measurement Magazine 24-9 - Cover3
Instrumentation & Measurement Magazine 24-9 - Cover4
https://www.nxtbookmedia.com