For this type of application you might consider using double walled
tubing (you can find copper in copper from brewery suppliers or
companies that make heat exchangers) and a recirculating chiller/heater
with antifreeze or ethylene glycol in the outer jacket and your gas mix
in the inner tube.  The nice thing about this approach is that the
temperature is set in the recirculator and it is very uniform.

-Mike Martin
  U. of Louisville


>>> "Ian Burnett"  08/24/06 12:08 PM >>>
Hi Amron, I would try to use electrical pad heaters which can be stuck
onto
the chamber outside and are very effective at heating up large areas.
They
can be temp controlled also and run off the mains supply. You can buy
then
in 10" or so strips or smaller pads and use several of them, but you
cannot
cut them as they have integral wires. Tyco make then and they are called
"Silicone pad heaters"