RF Charge Exchange Ion Source (Alphatross)

Product Features

Conveniently produces H^–, NH^–, O^– and other ion beams
Simple to operate
Compact
Long lifetime: over 1,000 hours of beam time between maintenance while producing 2 µA of He^–

The NEC RF charge exchange ion source – also referred to as Alphatross – was designed primarily for the production of He- beams for injection into tandem accelerators. The source can also produce H^–, NH^–, and O^– beams. Contact us to learn more.

There are now more than one hundred Alphatross sources in use on tandem accelerators worldwide.
Contact us to learn more and start an order.

Application

Modern MeV ion beam analytical instruments require a long lived and simple-to-operate source of He-, H-, and NH- beams. The NEC’s Alphatross RF charge exchange ion source satisfies these requirements. H- is used in Particle-induced X-ray Emission (PIXE) applications, while NH- is used for Nuclear Reaction Analysis (NRA).

How It Works

The only way that the He^– ion can be formed is by a two-step process that involves the production of the He⁺ ion followed by charge exchange using an alkali metal vapor:

Helium gas (for He^–), hydrogen gas (for H^–), or a gas mixture (for NH^–) is bled into a quartz bottle.
An RF oscillator is connected to the quartz bottle to disassociate the neutral gas.
The beam exiting the quartz bottle is immediately injected into a rubidium vapor charge exchange cell, converting the gas into a negative ion beam.

NEC’s RF Charge Exchange Ion Source Design

The entire source is housed in an RF sealed enclosure to protect nearby electronics.
The rubidium vapor remains trapped in the charge exchange cell by air cooling to the cell body and liquid cooling to baffles at the entrance and exit to the charge exchange cell (this ensures a long ion source life).
The use of a quartz bottle allows for strong plasma.
The quartz bottle can be cleaned and reused, has a long lifetime, and uses an o-ring seal for quick bottle changes.

Configurations

A typical NEC Alphatross system includes:

The source
Gap/einzel lens
Cooling system
Source gas unit
Power supplies

NEC can provide just the source, a complete injector system, or anything in-between.

NEC’s RF Charge Exchange Ion Source Performance

Below is a list of beam currents that have been produced by NEC’s Alphatross.

2-3µA He^–
>10µA H^–
>10µA O^–
2-3µA NH^–

This list does not represent the limit in capabilities of the ion source. All elements that can exist in the gaseous form and form negative ions could be considered candidates for ion production in the Alphatross. Please contact NEC with any questions about potential applications or performance.