Browse Prior Art Database

New Probe Insert for a Thermospray Interface that Allows Rapid Replacement of Clogged Probes at Nominal Cost

IP.com Disclosure Number: IPCOM000107643D
Original Publication Date: 1992-Mar-01
Included in the Prior Art Database: 2005-Mar-22
Document File: 3 page(s) / 125K

Publishing Venue

IBM

Related People

MacMahon, T: AUTHOR

Abstract

One of the major problems encountered when operating a thermospray interface is the continual clogging of the approximately 100-micron opening in the vaporizer tip. The reason this tip clogs frequently is because of the nature of the thermospray process. The thermospray vaporization process deposits involatile species at the tip which degrade the performance and eventually clog the tip (1,2,3). There are other mechanisms that also lead to clogging. For example, if the solvent or analyte contains particles 100 microns or larger, they can lodge in the probe and clog it. To this end .2 micron filters are installed on the inlet to the probe. In the lab, compounds have been run which polymerize at about 200~C.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

New Probe Insert for a Thermospray Interface that Allows Rapid Replacement of Clogged Probes at Nominal Cost

       One of the major problems encountered when operating a
thermospray interface is the continual clogging of the approximately
100-micron opening in the vaporizer tip.  The reason this tip clogs
frequently is because of the nature of the thermospray process.  The
thermospray vaporization process deposits involatile species at the
tip which degrade the performance and eventually clog the tip
(1,2,3).  There are other mechanisms that also lead to clogging.  For
example, if the solvent or analyte contains particles 100 microns or
larger, they can lodge in the probe and clog it. To this end .2
micron filters are installed on the inlet to the probe.  In the lab,
compounds have been run which polymerize at about 200~C.  Analyzing
these compounds can result in replacement of the probe 3 or 4 times
in one day due to the polymerization reaction occurring near the tip.
Once the probe has become clogged, one can try removing the clog by
chemical means (1), but there has not been much success with those
methods.  The design adopted by a number of instrument companies
involves replaceable probe tips which can be removed and cleaned or
discarded.  If replacement of the tip does not solve the problem,
then one must replace the entire probe.  These probes are generally
expensive and, if probes have to be replaced a few times a day, the
cost becomes prohibitive.

      There have also been a number of designs in the literature
which claim to solve the clogging problem.  One uses laser drilled
apertures which can be reused after cleaning (2).  The insert closest
to the design described in this article has a very simple and
straightforward probe replacement (3).  The replacement requires the
spot welding of the TC1 and TC2 thermocouples onto a 1/16-inch piece
of capillary tubing which is then inserted through a modified
Swagelok* fitting into the vacuum chamber.

      The two probes designed are similar to each other and are shown
in Figs. 1 and 2, respectively.  (These probes were built by
Scientific Instrument Services, Ringoes, New Jersey.)  With these
designs no spot welding is needed when replacing the probe inserts,
and the capillary tubing is supported into the probe handle to
minimize vacuum leaks. In the first design, a 1/16-...