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

The NEC SNICS II (Source of Negative Ions by Cesium Sputtering) generates ion beams by accelerating cesium ions onto a sample target (cathode), which sputters out negative particles from the sample. Contact us to learn more.
The unique design of NEC’s SNICS II – including a metal/ceramic construction with no organic seals in the main housing of the source – has produced a reliable system with superior performance. The SNICS II sputter cathode source is the most versatile negative ion source presently available, producing ion beams for all elements that form a stable negative ion.



NEC manufactures negative ion sources for a variety of applications. SNICS II is designed as a heavy-ion source and is used in diverse applications, including ion implantation and damage studies. There are now over 100 SNICS II ion sources in use on Pelletron® accelerators and other tandem accelerators throughout the world.


How It Works

diagram of SNICS internal components

How It Works: The cesium sputtering operation produced by the SNICS


SNICS Design

The SNICS II has multiple design considerations that allow it to maximize beam production.

The SNICS II has an all-metal sealed main housing. The only o-rings are in the back of the cooled area on the cathode holder. This arrangement allows the body of the source to remain warm relative to the cathode.

The volume around the ionizer and cathode is fully enclosed, which keeps the cesium vapor in the volume.

Provisions are available to adjust the cathode insertion position while the source is running, optimizing beam current. Adjusting the cathode position can also allow longer runs on a single cathode by optimizing the amount of material used per run.



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 or 134 samples at a time.




A typical SNICS system includes:

NEC can provide just the source, a complete injector system, or anything in-between. Contact NEC for more information on SNICS injector systems.

SNICS Performance

The maintenance period of the SNICS II is dependent on beam type and beam current produced. However, customers reported 3-6 months between source maintenance, except for cathode change. This translates into well over 1000 hours of beam production time.
The lifetime of a cathode is highly dependent on the sputter rates. However, the source is designed to allow the change of a cathode without turning the source off. In Pelletron® systems, it is common to change a cathode within 10 minutes from beam on target to beam on target.
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.

Examples of 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

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