Thin-film gauges are classic fast-response sensors for very fast
transient heat flux measurements with frequency responses up to
1 MHz [13–20]. They are usually fabricated by painting or sputtering
a thin resistance layer onto an insulator substrate so they are
usually fragile due to the weak layer-substrate bonding. Coaxial thermocouples
[21–24] are more rugged than thin-film sensors and do
not require frequent maintenance for transient heat flux measurements
in harsh thermal environments. Irimpan et al. [23] designed
a fast response coaxial thermocouple for shock tunnel applications,
evaluated the coaxial thermocouple response against a
platinum thin film gauge for heat flux measurements in a shock
tunnel. However, the short working time characteristics of the thin-
film gauges and coaxial thermocouples greatly restrict their
applications