A monitoring system for sensing temperature inside a process chamber 11 of processing apparatus comprises a fluid flow duct 12 extending through the chamber 11 and temperature sensors 16 for sensing the temperature of fluid flowing along the duct 12. A mica-based layer is wrapped around a length of the wire bundle and a fiberglass layer is disposed over the mica-based layer. The forward arm supports a mailbox platform, to which a mailbox can be attached. The rotor is rotatable within the cavity.