Saddle antenna radio frequency ion sources

Area of Science:

• Plasma Physics
• Accelerator Technology
• Ion Source Development

Background:

• Existing radio frequency (RF) ion sources for accelerators exhibit limited efficiency in H(+) and H(-) ion generation.
• Current systems require substantial RF power (∼50 kW) for moderate beam currents (50 mA).

Purpose of the Study:

• To develop an improved Saddle Antenna (SA) surface plasma source (SPS) for enhanced H(-) ion production efficiency, reliability, and availability.
• To investigate the performance of the SA SPS in both pulsed and continuous wave (CW) modes.

Main Methods:

• The study details the design and testing of the SA SPS, focusing on modifications for improved cooling and cesiation stability for CW operation.
• Performance was evaluated based on H(-) ion current generation relative to RF power input and emission aperture size.

Main Results:

• The SA RF ion source demonstrated a significant improvement in positive ion generation efficiency to 200 mA/cm(2) kW.
• Cesiation increased negative ion current from 1 mA to 10 mA (at ∼1.5 kW RF) and up to 30 mA (at ∼4 kW RF) for a 6 mm aperture.
• Continuous wave operation achieved stable H(-) beam generation up to 7 mA with ∼1.2 kW RF power, utilizing an Aluminum Nitride (AlN) discharge chamber.

Conclusions:

• The SA SPS offers a substantial advancement in H(-) ion source technology, providing higher efficiency and reliability.
• The demonstrated stable long-term generation of H(-) beams in CW mode with an AlN chamber indicates its potential for future accelerator applications.