I am not sure if you are talking about accelerating the electrons from the electron gun or the formed ions from the ion source.
As I recall, the default ionization energy (the result of acceletating electrons) is 70 eV. I have changed the voltage in a 72 or a 73 (And I am pretty sure it was a 72), but it was about 10 years ago and without access to one of those instruments now, I cann't tell you how I did it.
By the way the objective was to see if I could do soft ionization - which worked, kind of. If you drop the voltage low enough, you do get primarily the molecuar ion formed - apparently. The trouble is the signal has dropped to next to nothing...
If you want to change the accelaration of ions out of the ion source and into the analyzer, you would change the voltage on the repeller.
