Velocity Selectors

EXB Velocity Selector The NEC E x B velocity selectors provide mass and charge state separation of ion beams. Charged particles passing through orthogonal electric (E) and magnetic (B) fields are deflected unless their velocity equals E/B.

Several models are available. All models use permanent magnets to feature "one knob" control of E/B settings and to minimize power requirements. A 0-10 V input signal controls a pair of power supplies for providing the positive and negative voltages to the electric field plates. The following table provides data for our standard models. NEC can also provide customers with custom solutions, such as different aperture sizes, for their applications.



Velocity Selector Models
VS5-502 VS5-504 VS5-506 VS5-508
Electric Field Plates
(L x W x Gap)
3 x 7/8 x 5/8 (in.)
7.6 x 2.2 x 1.6 (cm)
6 x 7/8 x 5/8 (in.)
15.2 x 2.2 x 1.6 (cm)
4-7/16 x 1 x 5/8 (in.)
11.3 x 2.5 x 1.6 (cm)
2 x 7/8 x 5/8 (in.)
5.1 cm x 2.2 x 1.6 (cm)
Plate Power Supplies
(one pos., one neg.)
0 to 2.5 kV
1 mA
0 to 2.5 kV
1 mA
0 to 10 kV
7.5 mA
0 to 2.5 kV
1 mA
Magnet Poles
(L x W x Gap)
2.9 x 1.9 x 1.23 (in.)
7.4 x 4.8 x 3.1 (cm)
6 x 1.9 x 1.23 (in.)
15.2 x 4.8 x 3.1 (cm)
4.2 x 2.1 x 1.5 (in.)
10.7 x 5.3 x 3.8 (cm)
2 x 2.1 x 1.25 (in.)
5.1 x 5.3 x 3.2 (cm)
Magnet Type
Max Field (on axis)
Ceramic
1200 Gauss
Ceramic
1500 Gauss
Samarium Cobalt
2300 Gauss
Samarium Cobalt
3300 Gauss
Entrance Aperture
Exit Aperture
3/8 in. (0.95 cm)
3/64 in. (0.12 cm)
3/8 in. (0.95 cm)
3/64 in. (0.12 cm)
9/16 in. (1.4 cm)
3/8 in. (0.95 cm)
5/8 in. (1.6 cm)
3/8 in. (0.95 cm)
Mass Resolution Depends on ion beam/species and aperture sizes.

For orders, inquiries, comments and more information about our products, please contact our sales department at nec@pelletron.com

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National Electrostatics Corporation
Last revised December 3, 2001 by Tim Davis, nec@pelletron.com
Comments and suggestions about this website are welcome.
URL: http://www.pelletron.com/velsel.htm