ABS tune-up / commissioning
---------------------------
Status August 10, 2002, 11pm
In the past week we have been working on setting up the ABS for
measurements of the degree of dissociation for hydrogen dependent
on O2 contribution, gas flow, RF power, and nozzle temperature.
We succeeded to set up and debug the electronics and control
devices and DAQ in a stable and reproducable way and started to
take data in a range of parameters that allows us to determine
the weeknesses of the setup and show where major fixes are needed.
As a first result we measured a degree of dissociation of 65% for
hydrogen in a wide range of parameters, which turned out to be
very stable but also a hard limit. A possible reason for this
hard limit in degree of dissociation can be a contaminated hydrogen
bottle that we will investigate tommorow.
Tonight we switched to deuterium and finally reached the goal,
a degree of dissociation of 80% immediately in the first
measurements with 20sccm and 150W delivered power at a nozzle
temperature of 100K. We were able to repeat the results at a
flow of 70 sccm and we have good indications already that this
is a general result for measuremets with deuterium. These results
show that our system is in good shape and that a possible
contamination of the hydrogen is very likely.
On Monday we will open the system and start to improve and upgrade
the system. There is work to do on the chopper geometry, the
position of the QMA and pumping in the dissociator chamber, skimmer
chambers, and the forevacuum system.
Shifts will resume next week on Tuesday or Wednesday dependent on
the status of the upgrades.
Hauke
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