presents the change of frequency measurement uncertainties
for the experimental results given in Fig. 4. For each
current I, the uncertainty grows with the pressure but it presents
small values in the pressure range where the micro-thermocouple
is sensitive (between 100 and 1000 Pa). The frequency versus
pressure curve presents the lowest relative uncertainties
Df/f for
the current I ¼ 12 mA in the pressure range 10
2
Pae10
Pa.