Thermionics manufactures a full line of sputter ion pumps.

  • Standard Diode Pumps (IP Series)
  • Noble Diode Pumps (NP Series)
  • Hydrogen Diode (HP Series)
  • Triode Pumps (TP Series)

Each pump features:

  • Specific application design
  • Able to provide continuous and contaminant free pumping
  • Reliable from one micron to 2 x 10-11 Torr (measured)
  • Free from backstreaming
  • Bakeable to 300°C assembled
  • Bakeable to 450°C magnets removed
  • Able to act as its own vacuum gauge

All pumps are manufactured to exacting UHV standards. Pump bodies, flanges and element anodes are made of 304 stainless steel, bakeable to 450°C. Double reentrant electrical insulators are made of high-quality aluminum oxide, bakeable to 450°C, and are equipped with sputter shields. Pump magnets are high-strength ferrites bakeable to 300°C.


Pump Characteristics Normalized to the Standard Diode

Pump
Type
Air
Speed
Argon Speed
(% of air)
Hydrogen
Speed
Starting
Performance
Life Time at 
1 x 10-6 Torr
Standard
Diode
100% 1% 200–270%
Light duty only
Average
10µ
5 x 104
hours
Noble
Diode
95% 6 to 20% Not
Recommended
Below average
5 x 104
hours
Hydrogen
Diode
100% 1% 200–270%
Light duty only
Average
10µ
7.5 x 104
hours
Triode 85% 21% 200–270%
Light duty only
Average
10µ
5 x 104
hours

 


Ion Pumps

Choosing the Right Pump for Your Application


Standard Diode Pumps use two titanium cathodes in each pumping element. They are the pump of choice for most applications for their long life, reliability and high speed per unit . These pumps are not recommended when significant amounts of hydrogen or noble gases are to be pumped or where frequent high-starting loads are encountered.


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.


Hydrogen Diode Pumps are also similar to standard diodes. There are two differences in construction. The first is a thicker cathode. Because hydrogen diffuses into titanium like water into a sponge, the more titanium, the more capacity for hydrogen the pump has. This absorption of hydrogen can lead to a structural problem, however. Titanium swells and distorts as it absorbs large amounts of hydrogen. Therefore, hydrogen pumps have special structural modifications to prevent distortion from causing electrical shorts.

These extra construction details make the hydrogen diode a good choice for long pump life applications. Examples might be pumps operating in radioactive environments or operation at remote locations. Recommended when the major gas load is hydrogen or hydrogen-containing gases such as water va. It also pumps other non-noble gases.


Triode Pumps use reverse electrical polarity and a radically different cathode design to achieve two important advantages over the diode pumps: (1) an electrically isolated cathode allows the starting glow discharge to be confined at significantly higher pressures, resulting in shorter starting times; (2) the sputter cathode design allows noble and non-noble gases sputtering. Triodes have the highest speeds for noble gases and freedom from argon instability in the event of an air leak. Disadvantage: because of the sputter cathode design, the triode pumps require more frequent service.