The attached files display the results of the most recent DME ageing
tests.  Brief descriptions and comments on each test follow:

E29 REF - reference chamber (no ageing)

E30 PRH (TEF) - Pure DME (no deliberate contaminants), hi-rate to
Q=0.666 C/cm.  After that a corregated Teflon tube was inserted in gas
stream.  No significant damage in either case.

E31 PLG - Plug Valve (a type of valve considered for gas system)
inserted in gas stream.  Obvious extreme damage ... this type of valve
was not used in gas system.

E32 BLV - Ball Valve inserted in gas stream.  This type of valve is used
in gas system.  Some minor ( <10%) damage after ~ 0.4 C/cm (probably ~5
times more charge than expected over life of experiment).

E33 LDP (NEO) - low density polyethylene straw (as used in chambers) in
gas stream to 0.276 C/cm.  After that straw removed and replaced with
corregated neoprene tube.  No significant damage in either case.

E34 LTX (LTT) - latex compound (as used in chambers) in gas stream to
0.288 C/cm.  After that replaced with latex tube.  No significant damage
in either case.

E35 RTV - RTV silicone rubber in gas stream.  Used to compare with E36
below.  Extreme damage evident.

E36 RTF - gas stream was split after passing over the RTV of E35, one
stream continued thru E35, other stream passed thru R3-11/sieve filter
then thru E36.  Minor damage (<10%) evident after ~ 0.229 C/cm.  Filter
appears to trap "damaging" component of RTV outgassing.

E37 PRL - "pure" DME (no deliberate contaminants) low-rate. No
significant damage until >0.05 C/cm.  Then fairly rapid damage between
0.05< Q <0.11 C/cm.  No further damage 0.11< Q <0.19 C/cm.  I intend to
investigate if these periods correlate to particular source gas
cylinders, or other commonalities.  It's interesting (confusing) that
E38 (below) which had same source gas and same current density (i.e.
adjacent cell) does not show a similar pattern of damage.

E38 AWL - AWL3100V electronic flowmeter in gas stream, low-rate.  No
significant damage.

E39 UV1 - "pure" DME to 0.008 C/cm, after that "9-911" UV curing
adhesive in gas stream.  Extreme and rapid damage after insertion of UV
adhesive.  This test represents my personal record for fastest and most
complete damage ever seen.  Recommended that this glue not be used in
the chambers.

E40 UV2 - "pure" DME to 0.008 C/cm after that "X-306-96-A" UV curing
adhesive inserted in gas stream.  Rapid initial damage (~ 50%)  at
Q=0.027 C/cm.  Damaged area then got significantly better and stayed
that way ( ~ 10%) 0.027< Q < 0.086.  May indicate an initial "liquid-like"
deposit which subsequently dries up leaving a small residue on the wire.

     Future proposed tests:

Ageing test of PPP
Repeat low rate "pure" DME test
Repeat Ball Valve test at low rate
Test HR3 distribution needle valve (we have 56 in gas system)
Test AWM3100V.  We have tested the AWL which is the unamplified version
of the AWM which we'll actually be using 56 of.   Specs say they have
the same materials exposed to gas, but maybe should test anyways.

Filename: e29_32.ps

Filename: E33_36.ps

Filename: e37_40.ps

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