60 years of Ion Pumps from invention to the latest development.

Alessandro Abatecola

Ion Pump Marketing Manager

Agilent Technologies Vacuum Product Division

Une immersion dans le monde de l’Ultra Haut Vide : 60 années de pompes ioniques, de ses origines à ses dernières innovations.

Présentateur : Alessandro Abatecola

Depuis la fin des années 50, lorsque la pompe ionique fut inventée chez Varian (maintenant Agilent Technologies), de nombreuses

évolutions techniques ont vu le jour.

Agilent Technologies fut à l’origine de toutes les innovations majeures apparues sur le marché : de la première pompe ionique Diode

à la pompe ionique Triode, puis StarCell; de la gamme de pompes ioniques VacIon Plus à l’unité de contrôle 4UHV pouvant alimenter

jusqu’à 4 pompes ioniques indépendamment et assurer une lecture de la mesure de vide pour chaque pompe, tout en optimisant les

vitesses de pompage grâce à une tension variable.

Bien que les pompes ioniques soient largement et principalement utilisées dans les conditions UHV, la vitesse de pompage maximale

des pompes ioniques se situe aux environs de 10-6 mbar (10-4 Pa). L’intensité de la décharge dans la cellule penning de la pompe

ionique (nombre d’ions qui bombardent la cathode par unité de temps) est fonction de la pression, et est le principal paramètre de la

vitesse de pompage.

Une nouvelle pompe ionique de 200 l/s spécifiquement conçue pour opérer en UHV incorpore ces découvertes pour obtenir une

vitesse de pompage maximale vers 10-8 mbar (10-6 Pa). Nous vous décrirons comment les différents composants de cette pompe

sont traités thermiquement avant assemblage afin d’obtenir le vide limite le plus bas du marché.

Après plus de 60 ans, la pompe ionique reste une pompe inégalable pour l’Ultra Haut Vide, et Agilent reste à la pointe de

l’innovation.

60 years of Varian/Agilent Ion pumps ...AFTER INVENTION OF KLYSTRON BY RUSSEL VARIAN.....

• 1948: VARIAN BROTHERS CO-FOUNDED VARIAN ASSOCIATES

Original activities were focused on MICROWAVE ELECTRON TUBES

Ion pump was invented as the solution for clean pumping of electron tubes

• 1957: INVENTION OF SIP BY R. JEPSEN, L. HALL, J. HELMER

From a single cell to a multi-cell anode

• 1959: VACUUM DIVISION OF VARIAN

Production of Ion pumps starts - VacIon® Pumps

• 1960 – INVENTION OF TRIODE PUMP

Then commercialized by Varian in late 1960 under name “Noble Ion pump” (changed into Triode Ion pump in early 1979)

• 1967- Ion pump manufacturing site in Torino -Italy

In the same years the first installation of large SIP was at CERN in Geneva from 1971 – 1984

• INTEGRATION OF TSP and NEG CARTRIDGE WITHIN SIP BODY

Used since early history to improve UHV performance of SIP

Equipped with cooling and shields

• TURBOMOLECULAR PUMPS OVERCOME HV OPERATION OF SIP

Complimentary of SIP toward the higher pressure

All the attempts to improve high pressure operation were stopped and obsoleted by the introduction of TMPs

SIP starts below 10-6 mbar this create a «clean» alternative for high pressure

• STARCELL SIP (1983): RE-DESIGN OF TRIODE ELEMENT

After two decades of experience – same triode electrode and anode configuration -

but developing a new cathode structure

Extended life time, hydrogen pumping, Ar stability

• HOMOGENEITY OF MAGNETIC FIELD (I.B)

All cell operative at low pressure

Additional secondary manget with Axial-simmetric design

Enhanced homogenity

Higher pumping speed (especially at low pressure) / no increased in the overall dimension

• OPTIMIZED VOLTAGE AT EACH PRESSURE RANGE (Multivac/DUAL C.U. (1990) Through the «STEP» option

Benefit:

Change the voltage according to pressure (read throguht Ion current)

Optimized pumping speed in the whole pressure range

Reduced leakage current

• SEM SPUTTER ION PUMP (2002)

Desinged for E-GUN OF scanning electron microscopes

Less dendride (wiskers) formation, less field emission

less leakage current spike

Reliable pressure reading

• A NEW ERA IN THE CONTROLLER UNIT: 4UHV introduction (2009)

Up to 4 pumps driven simultaneously and indipendently

Any type of element (SC-DI-ND) and mixed combination

Variable voltage (STEP mode) ensures optimum pumping speed and pressure reading

Different Power

• STANDARD PUMP FOR PARTICLE ACCELERATOR:

ESRF (FR)- SOLEIL (FR) – PSI (CH)- DESY (DE) – POSTECH (KR) – FERMILAB (US)-

Special customized pumps: -DESY-XFEL (DE)- LIGO-(2500l/s)- NSRRC (100l/s - TW)

Ie. DESY: Together with DESY, Agilent Technologies developed an

inline vacuum pump that can be directly mounted into

a beamline, improving effective pumping speed and

Shielding.

Have you ever seen a pump with maximum pumping speed at low

pressure ?

What new features can be still introduced?

What else can be still invented?

Ion Pump design for improved speed at low pressure

Scope of the work:

Ion pumps are normally used at low pressure , 10-8 mbar ( 10-6 Pa ) and below.

Existing ion pumps have maximum pumping speed in the 10-6 mbar (10-4 Pa ) range.

Analyze influence of design parameters on pumping speed of an ion pump.

Experimental test of elements with different parameteres in different operating conditions.

Goal is to optimize these parameters to improve the overall pumping speed

and improve it at lower pressures

Ion Pumps main pumping principle (for getterable gases)

Penning Cell , crossed B and V act as an electron trap

Electrons ionizes gas molecules through collisions

Ions are created in order to bombard the Titanium cathode

Even if some ions diffuse into the cathode, this is not the main pumping effect

Sputtering of chemically active Titanium film on the anode

Neutral Gas molecules stick to the Titanium film (chemisorption) and are buried in the anode

This is the main pumping effect and the only stable one

We can summarize that:

Ion pumps do not pump ions by diffusion into the cathode , but pump neutral molecules by

chemisorption by the sputtered cathode material on the anode

Discharge intensity in Low Magnetic Field and High Magnetic Field modes

Low pressure

High pressure

P (mbar) @ 7 kV @ 5 kV @ 3 kV 1,00E-06 1256 1061 823 1,00E-07 1409 1191 922 1,00E-08 1580 1336 1035

1,00E-09 1774 1499 1161 050

637.

a

a

transitionPr

V.B

20 mm dia cell

I/P measurements - Experimental set up

Rough Valve

1

2 3

4

5

Vacuum chamber: UHV gauge,

variable leak valve, independent ion

pump

“special” ion pump body with HV

feedthrough

Electromagnet poles

Ion Pump element to be tested

Pump Parameter Design

Dia , mm Area , mm2 No of Cells

16 201 75

20 314 48

24 452 33

28 615 24

Optimum Magnetic Field for I/P 1400 / 1600 Gauss

Present Ion Pumps work with 1100/1200 Gauss, obtainable with commercially available magnets and

conventional design

Optimum cell diameter 20 to 24 mm

We have to work on Magnetic Field

Present Ion Pumps have cells from 15 to 25 mm diameter

Ion Pump Magnetic field

Conventional, 150 l/S New design, 200 l/s

Ion Pump Magnetic field

Conventional

New design

Red 900 G

Orange 1000 G

Yellow 1250 G

Grey > 1500 G

Pumping speed after saturation, Nitrogen

0

50

100

150

200

250

300

350

1,E-11 1,E-10 1,E-09 1,E-08 1,E-07 1,E-06 1,E-05

S (

l/s

)

P (mbar)

7 kV - N2 Diode

5 kV - N2 Diode

3 kV - N2 Diode

Unsaturated

Innovative Vacuum Treatment process -XHV

Innovative application of Vacuum Firing* process

Applied to ALL surfaces exposed to vacuum

(before pump’s assembly)

Effectively reduces the Hydrogen outgassing rate (up to 90%)

Boost capability to reach eXtreme High Vacuum (XHV) levels.

Process largerly used in the WW research Centers

Applied to VIP200 pump’s family only: first Pump in the market

Vacuum

Firing

Summary

I/P values have been measured for a wide range of Ion Pumps key design parameters such as V , B , cell dimensions

The influence of B on I/P has been experimentally measured and a value higher than the one used in existing ion pumps has been proved to be necessary to improve the performances, especially at lower pressures.

With optimized design parameters it is possible to design an ion pump with the highest pumping speed per unit volume ( 200 l/s in the same dimensions of conventional 150 l/s).

Even more important, the maximum pumping speed of 200 l/s is reached in the 10-8 mbar (10-6 Pa ) range, where a conventional 150 l/s usually provides 125 l/s

Next step: to extend the same design to different sizes of ion pumps

New Agilent VIP200 eXtreme High Vacuum Performance

Courtesy of CERN

The first ion pump with maximum pumping speed at low pressure