Toroidal Volume Ion Source (TORVIS)
- Highest current source for H– and He–
- Stable over a wider range of conditions
- Operates with ease
- Servicing interval is over 1,000 hours of beam time
The NEC Toroidal Volume Ion Source (TORVIS) is our highest current source for negative ions of hydrogen, deuterium, and helium. It is designed for efficient injection into tandem electrostatic accelerators.
The TORVIS is designed as a high current source and is used for a variety of applications, including Ion Beam Analysis (IBA), neutron generation, and damage studies.
Toroidal Volume Ion Source Design
The TORVIS is a compact source in a 5″ diameter housing containing about 500 rare earth magnets.
How It Works
- High current H–/He– ion source with a toroidal discharge chamber, where negative protons are directly extracted from the source.
- Rubidium vapor charge exchange cell for negative helium production.
- Compact vacuum chamber completely surrounded by small permanent magnets arranged to create a surface of magnet cusps that mirror the ions and electrons away from the walls of the chamber.
- Central magnet placed on the back plate of the ion source directly opposite the beam exit aperture, producing a conical region that contains slow electrons and filters out fast electrons to reduce destruction of the negative ion.
A TORVIS injector system can be configured in three different ways depending on the desired beam species:
- H– only version: optimized for hydrogen isotopes (protons and deuterium)
- He– only version: optimized for He–. The source alone produces positive He ions, and the addition of a charge exchange cell allows the production of He–.
- H– and He– version: capable of producing protons, deuterium, and helium. Includes the charge exchange cell.
Toroidal Volume Ion Source Injector Performance
Beam currents (after mass analysis) are stable at 300 to 500 microAmps for H– and routinely measured at 20 microA for He–. Please contact NEC with any questions about potential applications or performance.
The toroidal volume ion source has proven to be very reliable with typical filament lifetimes lasting well beyond 1,000 hours.
Paper presented at 2005 IBA conference