Have you checked for shorts between filament/trap and the source block?
The 1.5mA you are seeing is probably the emission current limit coming
in. If the source collimating magnets are in the wrong way round then
this will also give high emission.
Incidentally when you cleaned the source did you replace the titanium
ion exit slit or just clean it? They get sputtered from the ion beam and
then the slit elongates into an "S" shape. According to Thermo they
should be changed every few years and are very expensive.
University College London
On 14/07/2010 16:53, France, Christine wrote:
> Hello Isogeochemers,
> I recently cleaned the source and replaced the filament on my Delta V
> Advantage. The original symptoms included jumpiness and variability in
> the box and trap over the last couple weeks leading up to a complete
> loss of emission and a trap value of 0mA. I pulled the source, cleaned
> everything, and installed a new filament.
> When I turned it on my box reads 1.5mA and my trap also reads 1.5mA. I
> am seeing an emission signal, but these values are much higher than the
> expected 0.7-0.8mA range. I’ve dealt with issues where my box was 1.5mA
> and the trap 0 due to a short in the source, but I’ve never seen them
> both so high. Could this be due to a similar cause (i.e. a short or
> leads touching in the source array) or am I dealing with something
> completely different? Naturally my vacuum came down quickly and it looks
> great – I’d hate to break vacuum again unless I absolutely have to. Any
> advice would be appreciated.