Gamma Vacuum
The science of advanced vacuum

Magnetic Field

Stray Magnetic Field

Directing particles can require extensive use of sensitive magnetic instruments. Coincidentally, ion pump operation utilizes a magnetic field of up to 1500 gauss. This intensive magnetic field is used to increase the mean-free path of electrons and is only needed in the element of the ion pump. The primary objective on the external sides of the ion pump is to eliminate any stray field that can affect system applications. Low Profile Ion Pumps are constructed with a closed magnetic loop that reduces stray magnetic field to near ambient levels. This is up to 10 times lower than other widely available standard designs. Eliminating stray magnetic fields reduces design effort in focusing, bending, and insertion devices that rely on the Lorentz force.

Pumping Speed and Temperature

The magnetic field directly affects the pumping speed of an ion pump. Above 85°C, the pumping speed declines with temperature. Ion pumps have difficulty maintaining operation above 250°C because of magnetic field loss. The ceramic magnets used exhibit reversible field loss of 0.2% per degree Celsius and an irreversible field loss of 7% at 350°C. This loss is non-cumulative (subsequent bakeouts to 350°C do not cause an additional irreversible loss). Above 350°C, permanent magnetic and/or physical damage can occur.


TiTan Low Profile 400
(blue = 0.2 gauss)

TiTan Tall Profile 150
(red = 3 gauss)

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