Source of Negative Ions by Cesium Sputtering (SNICS)


Product Features
  • The SNICS II is capable of creating over 60 different types of negative ion beams
  • Sources typically function for 3-6 months before requiring maintenance, except for cathode change
  • Cathode change time is within 10 minutes from beam on target to beam on target

Applications

The SNICS II is the most versatile negative ion source presently available. This sputter cathode source produces ion beams for all elements that form a stable negative ion. Its unique design and metal/ceramic construction with no organic seals in the main housing of the source has produced a reliable system with superior performance for all negative ions across the periodic table.

 

Design

diagram of SNICS internal components

A diagram showing the cesium sputtering operation produced by the SNICS

Cesium vapor flows from the cesium oven into an enclosed area between the cooled cathode and the heated ionizing surface.  Some of the cesium condenses on the front of the cathode and some of the cesium is ionized by the hot surface.  The ionized cesium accelerates toward the cathode and is focused on the front face of the cathode.  The ionized cesium sputters particles from the cathode through a condensed cesium layer on the cathode face.  In this way, negative ions are accelerated from the cathode surface.
The source is designed to allow the change of a cathode with minimal downtime.  In Pelletron systems, it is common to change a cathode within 10 minutes from beam on target to beam on target.

 

Performance

Customers report emittances of the resulting negative ion beam from a SNICS II source from 3-5 πmm mR (MeV)1/2 for 80% of the beam, depending upon the beam mass.

Some Negative Ion Beams Produced by SNICS II

 Negative Ion Current after Analysis (μA) Negative Ion Current after Analysis (μA)
 H 130 Br 60
 D  150  Zr  9.4
 Li  4  Mo  5
BeO  10  Ag  13
B2  73  I  220
C  260  Ta  9.5
CN  12  W  2.5
O  300  Au  150
Na  4  Cl  100
Al2  50  Fe  20
Si  430  Cu  160

This list is based on data from AT&T Bell Laboratories, the NEC test bench, and other contributing laboratories. All ion beam currents listed are measured after 30° or 45° mass analysis.

For a more complete list please reference the Related Documents section below

 

Options

Though the source is primarily designed for the use of solid samples, NEC offers a gas cathode assembly, which allows the insertion of gas through the center of a cathode.

NEC also offers a multi-cathode SNICS (MC-SNICS) that can handle either 40 of 134 samples at a time. Please click here for more information on our MC-SNICS, or contact NEC for more information on available configurations for the SNICS.


Related Documents
SNICS v1.pdf