Discovery TGA™ Getting Started Guide
Page 16
Infrared (IR) Furnace for TGA 5500
The IR furnace (shown below) uses quartz halogen lamps as the heat source. Four lamps are arranged in a
circular pattern surrounding the quartz tube that encloses the sample area. Infrared energy from the lamps
is directed toward the sample area by a water-cooled, gold-plated reflector consisting of four elliptical
surfaces.
The sample area is enclosed by a cylinder inside of the quartz tube. This cylinder absorbs radiation from
the lamps and heats the sample, pan, and thermocouple.
Figure 4
IR furnace cut-away diagram.
Temperature is measured and controlled by a thermocouple assembly under the sample pan. The thermo-
couple assembly includes a second independent thermocouple to protect the furnace from excessive
temperature.
Heat shield assemblies above and below the energy-absorbing tube reduce heat losses from the ends of the
furnace.
Purge gas enters the sample area through a tube within the quartz tube, passes through a hole in the wall of
the absorber across the top of the sample pan, through another hole in the wall of the absorber, and exits via
a second tube in the quartz tube.
A magnetic coil surrounding the furnace generates a field that acts on magnetic samples in the sample pan.
This facilitates automated temperature calibration using Curie point standards and Curie point studies.
Rapid cooling of the furnace at the end of an experiment is facilitated by air that enters the furnace cham-
ber through the bottom of the furnace.
Heat shields
Sample pan
Purge gas outlet
Thermocouple
Energy-absorbing
Purge gas inlet
Quartz tube
cylinder
