[labnetwork] Pyrogenic internal torch

[Paolini, Steven]

Scott,
  Over the years, I have had great results with MRL external torches. The main advantage is being able to see the combustion and whether or not the torch depth is correct. The other big advantage is being able to use a flame detector that will shut off the H2 flow in a couple of seconds (adjustable) to avoid injecting  gas continuously into a cold torch. You may be seeing uniformity issues with the coaxial if you have tiny air leaks being pulled into the tube from the ground glass joints. Are you using Teflon seals? In any event, please ensure that you are running the H2/O2 mix Oxygen rich to prevent accumulating H2 downstream.
  Equipment Dood

Steve Paolini
Principal Equipment Engineer
Harvard University Center for Nanoscale Systems
11 Oxford St.
Cambridge, MA 02138
617- 496- 9816
spaolini at cns.fas.harvard.edu
www.cns.fas.harvard.edu

From: labnetwork <labnetwork-bounces at mtl.mit.edu> On Behalf Of Scott Blondell
Sent: Tuesday, August 03, 2021 3:50 PM
To: labnetwork at mtl.mit.edu
Subject: [labnetwork] Pyrogenic internal torch

Greetings Labnetters,

We're in the process of tweaking our wet ox process. Hardware changes provided an opportunity to consider
alternatives to our current internal "candy cane" torch arrangement employed in several tubes. Currently running 6" silicon
in 205/211mm quartz w/candy cane torch. This doesn't give us the luxury of a simple visual inspection without pulling the tube.

A straight coaxial torch is being qualified now, and it's presenting some challenges. Growth rates are lower than predicted and
across boat uniform is >6%.

Polling the audience: what are your preferences - cane v straight?; straight torch design details/vendors?; gas flows?
There's a lot of knobs to turn - at 2/runs per day it's slow to fine tune.

We do have an MRL external torch that served us well for lower temp processes. Space and budget precludes using it in
multiple tubes.

Appreciate any feedback, tips or outright opinions.

Regards,

Scott P. Blondell
Fac. Mgr.
RIT SMFL
315.738.4073
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