LEFT PHOTO: The electrical connectors are seen for interfacing thermocouple to the DVM (left) for combustion temperature measurement, and for connection of the igniter to the ignition control box (right).
RIGHT PHOTO: Smoke issues from the top of the Combustion Chamber, taken during an actual test.
The Combustion Chamber is made from 1/2" black iron pipe, screwed into a cast iron base fitting, mounted on a steel base plated fitted with four legs.
The thermocouple is Type C, Tungsten-5% Rhenium vs Tungsten-26% Rhenium, slid through a pair of ceramic tubes epoxied inside a 1/8" black iron pipe, screwed into a tapped hole in the side of the Combustion Chamber.
A 'blowout pin', which consists of a press fit roll pin, is installed just below the thermocouple bead to protect it from damage (thermocouple is expensive!) in case of a possible ejection of the propellant sample due to failure of the bonding which attaches the sample to the base.