Noble Diode Pumps use one titanium and one tantalum cathode to increase pumping speed for noble gases. Increased speed eliminates the pressure and speed instabilities shown by standard diodes when pumping against a prolonged air leak while retaining the long life and reliability of the standard diode. These are the most stable pumps for noble gas loads.
Noble diodes were developed to pump noble gases. In every instance but one they are identical to a standard diode. The difference is the use of one tantalum cathode in place of one of the two titanium cathodes in the standard pump. The tantalum, because of its larger atomic number, produces a greater number of energetic neutrals which can bury themselves in locations which are less subject to resputtering.
Tantalum is somewhat less effective than titanium as a getter. Therefore the speed of the noble diode is approximately 5% lower than the standard diode. Another fact of note is the lessened solubility of hydrogen in tantalum at elevated temperatures. Since elevated temperatures will be encountered during prolonged starting, it would be wise to avoid applications which require this pump to handle large amounts of hydrogen. Naturally, applications differ. Should you have any questions about the applicability of a pump for your use, please give us a call. We have a wide variety of prior applications to draw upon.
* Pumping Speed Ratings for Ion Pumps
Some pumps in this table have two pumping speeds shown, i.e., 150/100. The lower number is observed when the measurement standard established by the American Vacuum Society (AVS) is followed. The higher number is observed when the same pump is measured under optimum pumping speed conditions. Some manufacturers use the optimum pumping speed, only reporting this higher number. Both ratings are provided here to allow the customer to make an informed choice.
1 All flanges ConFlat compatible except 1,000 l/sec pumps.
2 Heaters are model IH-100 Calrod heaters which fit into matching interior heater wells in most pumps.
3 IH signifies interior heater well available as option.
4 DE specifies a double-ended option.
5 No bakeout heaters available for this pump.
6 Larger pumps available on special order.