Occasionally Ion Pumps can short out from the flakes that accumulate over the years because of using titanium sublimation pumps (TSP). An old trick is to use a high potter (high voltage potential generator) to create an arc which can sometimes (if you are lucky) burn off the short. High potting can work well for ion pumps, ion guns and practically any electrical feedthrough on a vacuum chamber where flakes or deposition build up is an issue.
High potting will only work on small flakes as the current generated is low (100uA max). But the voltage generated is extremely high at 20,000 to 50,000 volts. Think of this as a small Van der Graaf generator where you can direct the arc towards the electrical feedthrough on the vacuum chamber. The voltage from the arc is applied to the shorted electrical feed though and will work it’s way to the short inside the vacuum chamber and if you are lucky, will melt the short.
High potting does not always work but when it does it buys you some time before you need to vent the chamber and perform the necessary maintenance to fix the underlying shorting issue.
Back in the 80s it was common to see high potters in labs that had vacuum chambers for analytical instruments or deposition systems. These days you do not see high potters as often due to more stringent electrical safety standards. Used properly a high potter is perfectly safe. Although it is a little bit exhilarating to be pointing a device that has a 50,000-volt arc coming out of the end. 😊
Electro-Technic Products, Inc. provides an assortment of high frequency generator testers that work well as high-potters (high voltage potential) to melt away small particles and flakes that can cause shorts in high and ultrahigh vacuum applications. In particular, these are useful for high-potting shorted ion pumps and ion guns.
We prefer the BD-10AS as it has an ON-OFF switch. As with all high voltage, only qualified personnel should use this device. Check with your organizations’ electrical safety officer to make sure that your organization allows high potter use before purchasing a high potter.
For more information or to place an order, contact Electro-Technic at http://www.electrotechnicproduct.com/pinhole.html
Or by phone at 773-561-2349