PSI - Issue 17

Kristýna Čápová et al. / Procedia Structural Integrity 17 (2019) 726 – 733 Kristýna Čápová et al. / Structural Integrity Procedia 00 (2019) 000 – 000

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• OrmocerT: bare optical fibre (primary protection material is OrmocerT) rolled onto a spool

Furthermore, the temperature sensed by the internal sensors in the interrogators and in the optoelectronic assemblies was recorded: • sys_cp_temp: cold plate temperature (a cooled plate with a spectrometer attached) • sys_internal_temp: temperature inside the interrogator, the sensor is located freely in the space above the control electronics • sys_ofls_temp: temperature deviation SLED from set value • sys_spc_int_temp: temperature on the internal sensor of the spectrometer (from the manufacturer) • sys_spc_temp: spectrometer surface temperature (added for testing purposes)

a

b

Fig. 2. (a) Interrogators placed inside the climate chamber; (b) Temperature / humidity sensor.

The aim of the testing was to verify the behaviour of the whole measuring chain and to gain knowledge for the next stages of experimental work. In particular, the temperature ranges in the first phase were limited below technically possible limits. An overview of parameters of realized and evaluated test is presented in Table 4.

Table 4. Configuration of realized and evaluated tests. No. of cycles Chamber Interrogators – temperature

Chamber Interrogators – humidity

Chamber Sensors - temperature

Chamber Sensors - humidity

Test 01: Verification of the tested configuration stability Test 02: Sensor response to ambient temperature change I Test 03: Sensor response to ambient temperature change II Test 04: Interrogator response to ambient temperature change

1

21 °C

50 %

21 °C

50 %

20 °C – 60 °C – 20°C (*) -30 °C – 70 °C – -30 °C (*)

6

21 °C

50 %

50 %

6

21 °C

50 %

50 % (no control below 0 °C)

0 °C – 40 °C – 0 °C (**)

4

50 %

21 °C

50 %

(*) hold the initial temperature for 30 min, temperature change in 1 °C/min ramp, after each 10 °C step hold for 30 min (**) hold the initial temperature for 30 min, temperature change in 0,3 °C/min ramp, after each 5 °C step hold for 30 min, hold the maximal temperature for 60 min The first phase of measurements in the environmental chambers lasted 25 days, significant results are commented in the following text. Long-term measurement stability was tested in Test 01 test file. Fig. 3 shows the time dependence of the relative temperature change measured by the internal sensor of FBGuard. The values are stable during the test, with the exception of the internal sensors of the interrogator located inside the box above the electronics. It can be seen that the internal temperature decreases shortly after the start of the measurement, and then remains constant. This is due to the cooling of the interrogator space by fans.