Transient Interferometric Technique Research Articles

A new numerical and experimental analysis tool for ESD devices by means of the transient interferometric technique

Two different protection diodes are investigated with electrothermal simulation and transient interferometric thermal-mapping experiments in a new complementary approach. The prediction capability of the simulation tool is validated up to the thermal failure of the p-n junction. The temperature distribution and its dynamics during the application of high-current pulses are studied by comparing the calculated and experimental optical phase shifts: a quantitative agreement both in temporal evolution and space distribution of temperature is obtained up to 1100 K.

Measurement of Thermal Expansion at High Temperature by a Transient Interferometric Technique

A transient interferometric technique to measure the thermal expansion of pure metals and alloys during rapid heating is presented. The metallic specimen is resistively heated from room temperature to a high temperature close to melting within approximately 500 ms by the passage of a high electrical current pulse. The temperature of the specimen is measured and time resolved by a fast pyrometer; the thermal expansion is obtained by a high-speed laser-interferometer. The device used is a modified polarized-beam Michelson-type interferometer with a phase-quadrature detector that distinguishes between expansion and contraction. Details of its principle, the construction, adjustment, and operation are described. In addition, thermal expansion measurements performed on molybdenum and tungsten standard reference materials (SRMs) are presented and compared with results obtained by other researchers.

Thermal expansion of tungsten in the range 1500?3600 K by a transient interferometric technique

The linear thermal expansion of tungsten has been measured in the temperature range 1500–3600 K by means of a transient (subsecond) interferometric technique. The tungsten selected for these measurements was the standard reference material SRM 737 (a standard for thermal expansion measurements at temperatures up to 1800 K). The basic method involved rapidly heating the specimen from room temperature up to and through the temperature range of interest in less than 1 s by passing an electrical current pulse through it and simultaneously measuring the specimen temperature by means of a high-speed photoelectric pyrometer and the shift in the fringe pattern produced by a Michelson-type interferometer. The linear thermal expansion was determined from the cumulative shift corresponding to each measured temperature. The results for tungsten may be expressed by the relation $$\begin{gathered} (l - l_0 )/l_0 = 1.3896 \times 10^{ - 3} - 8.2797 \times 10^{ - 7} T + 4.0557 \times 10^{ - 9} T^2 \hfill \\ - 1.2164 \times 10^{ - 12} T^3 + 1.7034 \times 10^{ - 16} T^4 \hfill \\ \end{gathered} $$ whereT is in K andl0 is the specimen length at 20°C. The maximum error in the reported values of thermal expansion is estimated to be about 1% at 2000 K and approximately 2% at 3600 K.

Thermal expansion of niobium in the range 1500?2700 K by a transient interferometric technique

Thermal expansion of niobium in the range 1500?2700 K by a transient interferometric technique

Thermal expansion of molybdenum in the range 1500?2800 K by a transient interferometric technique

The linear thermal expansion of niobium has been measured in the temperature range 1500–2700 K by means of a transient (subsecond) interferometric technique. The basic method involves rapidly heating the specimen from room temperature up to and through the temperature range of interest in less than 1 s by passing an electrical current pulse through it and simultaneously measuring the specimen temperature by means of a high-speed photoelectric pyrometer and the shift in the fringe pattern produced by a Michelson-type interferometer. The linear thermal expansion is determined from the cumulative shift corresponding to each measured temperature. The results for niobium may be expressed by the relation (l-l0)/l0=5.4424×10−3−8.8553×10−6T+1.2993×10−8T2 −4.4002×10−12T3+6.3476×10−16T4 where T is in K and l0 is the specimen length at 20°C. The maximum error in the reported values of thermal expansion is estimated to be about 1% at 2000 K and not more than 2% at 2700 K.

Transient interferometric technique for measuring thermal expansion at high temperatures: Thermal expansion of tantalum in the range 1500?3200 K

The design and operational characteristics of an interferometric technique for measuring thermal expansion of metals between room temperature and temperatures in the range 1500 K to their melting points are described. The basic method involves rapidly heating the specimen from room temperature to temperatures above 1500 K in less than 1 s by the passage of an electrical current pulse through it, and simultaneously measuring the specimen expansion by the shift in the fringe pattern produced by a Michelson-type polarized beam interferometer and the specimen temperature by means of a high-speed photoelectric pyrometer. Measurements of linear thermal expansion of tantalum in the temperature range 1500–3200 K are also described. The results are expressed by the relation: $$\begin{gathered} (l - l_0 )/l_0 = 5.141{\text{ x 10}}^{ - {\text{4}}} + 1.445{\text{ x 10}}^{ - {\text{6}}} T + 4.160{\text{ x 10}}^{ - {\text{9}}} T^2 \hfill \\ {\text{ }} - 1.309{\text{ x 10}}^{ - {\text{12}}} T^3 + 1.901{\text{ x 10}}^{ - {\text{16}}} T^4 \hfill \\ \end{gathered}$$ where T is in K and l0 is the specimen length at 20°C. The maximum error in the reported values of thermal expansion is estimated to be about 1% at 2000 K and not more than 2% at 3000 K.