This document discusses different types of getter pumps used in vacuum systems. It describes flash getter pumps, which use reactive metals like barium that vaporize at high temperatures to remove gases. Titanium sublimation getter pumps use filaments coated with titanium that sublimate to deposit a reactive surface. Non-evaporable getter pumps use porous zirconium alloys that chemically bond with gases when heated, providing a permanent pump.

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CHAPTER 15
GETTER PUMP
Gigin Ginanjar
01312003

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Content
• 15.1 General
• 15.2 Flash getter
• 15.3 Titanium Sublimation Getter Pumps
• 15.4 Non-Evaporable Getters

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15.1 General
• The general Idea is that when molecule strikes the gettering surface, it forms chemical
compounds and is removed from gas phase
• Gettering surface can be generated in several way including sputtering deposition,
evaporation and sublimation
• In most cases the surface saturation and no longer effective, it is regenerated.
• Some material call bulk getter. This material the active surface regenerated by heat to
cause the gas to diffuse of the material .
• For several different type molecules H2,H2O,CO2,N2,O2 interacting in the surface.
• If n is the number of molecules strikes unit area per second
• N is number of molecules per unit volume, is average molecular velocity
• Example if the molecules stick to surface and do not return to gas phase, for nitrogen
at room temperature. It represent pumping speed 11.6 liters/sec for square centimeter
of surface area.
N2

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15.2 Flash getter
• Common application flash getter is sealed
cathode ray tube and other form of
electron tube
• Flash getter place within chamber or glass
envelope with electron component and
pump down , sealed off and getter is
activated.
• Flash getter usually chemically reactive
metal which can readily vaporized. Alloy
Barium are common used. BaAl4 alloy will
decompose at 1000 oC giving Ba vaporized
and liquid Al.
• The getter can heated by RF induction or
by joule heating

5. Flash getter video
http://www.youtube.com/watch?v=gQBmt-z0w9g
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To vacuum pump( sealed off)
Heater
Flash getter

6. 15.3 Titanium Sublimation Getter
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Pumps
• This is often used in conjunction with an
ion pump. Titanium can readily deposited
by sublimation from a heated source called
Titanium Sublimation Pump (TSP)
• Wire type is made from four to six filament
on flange that heated by passing 20 to 50
Ampere of current.
• Filament made by of molybdenum-titanium
alloy which has characteristic that
when titanium sublimed leaving only
molybdenum, the resistivity lower in that
location reduce temperature. To prevent
catastrophic failure allow more titanium to
be sublimed.

7. Titanium Sublimation Getter
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Pumps
• Titanium sources normally operated only
intermittently.
• Chemically reactive gas like O2,N2,CO are pumped
very well, gas more stable H2O,CH4 are not pump .
• Rare gas like He, Ar, Ne are not pumped
• With ion/TSP pump receiving surface must far
enough form the filament so it does not heat up
and out gas. Is often made of copper and some
time can be cooled by water or liquid nitrogen
• For prolonged us, Ti flakes begin form can be
electrostatically attract to ion pump anode. And it
make anode short to ground and the pump not
working. Is necessary to clean chemically.

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TSP Video
http://www.youtube.com/watch?v=3_PSGE5XhQk

9. 15.4 Non-Evaporable Getters
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• Non –Evaporable Getter (NEG) or bulk getter consist
very chemically active usually zirconium or a
combination Zr and another material (Fe ,V, Ni ,
Graphite)
• The material are ground into powder using
manufacturing method. They compress in to solid
form which very porous (large surface area)
• After fabrication NEG material first exposed to air,
form thin protecting film which prohibit reaction with
atmospheric gases
• After installation NEG must be activated. By heating
400-900oC for 1-30 minutes
• During operation NEGs gas phase molecule strike
and react with the surface. Although this material has
large surface area. Heating also molecules diffuse
into bulk material. Most this material heat at 200-
400oC

10. Non-Evaporable Getters (1)
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• Pumping characteristic of these
material depends on its history.
• Total pumping speed and total
quantity sorbed would depend
on the area of material used
• Interaction of NEG material with
N2,O2,CO,CO2 and H2O cause of
nitrides, oxides, carbides
• Although than oxygen, carbon,
nitrogen will not released when
material heated.

11. Non-Evaporable Getters (2)
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• H2 Hydrogen does not react chemically with the
getter alloy. Dissociation occurs and individually
forming solid solution.
• The sorption of hydrogen is reversible. The
amount its depends on the temperature and
partial pressure of H2
• H2O molecule can absorb on the surface . For
diffusing into bulk material. Resulting hydrogen
and oxygen move to bulk. The pumping limited
by rate of dissosiation of H2O molecules
• Noble Gas, not pump by gettering. It possible
operate getter pumps in noble gas atmosphere
in order to improve the purity of the gas.
• NEG material can be purchase in various form
including ring shaped container. They available
as array parallel fins. The same as flash getter
usually operate in situation pressure reduced
below atmospheric pressure

12. Non-Evaporable Getters (3)
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• Relative pumping speed of
several gas compared to N2
• It depends on how much surface
area is available.
• To achieve larger pumping speed
one simple use more material.
• For situation getter in side
chamber the constriction of
tubing my become limiting factor
• For nitrogen at room temperature
this about 11.6 liters/sec per cm2.

13. Non-Evaporable Getters Video
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http://www.youtube.com/watch?v=wTRPAUoFJqQ

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Thank You