Power efficiency improvements with the radio frequency H⁻ ion source.

Area of Science:

• Nuclear Physics
• Plasma Physics
• Particle Accelerators

Background:

• Development of a continuous wave (CW) 13.56 MHz radio frequency-driven negative hydrogen ion (H-) source is underway at the University of Jyväskylä.
• The goal is to replace the existing filament-driven ion source for the MCC30/15 cyclotron.

Purpose of the Study:

• To report on the latest results and upgrade plans for the RF-driven H- ion source.
• To evaluate the performance of a new front plate design with a permanent magnet filter field.

Main Methods:

• Replaced the original adjustable electromagnet filter field with a permanent magnet filter field in the ion source front plate.
• Investigated the impact of the new front plate design on ion beam production and efficiency.

Main Results:

• Achieved the target intensity of 1 mA H- beam at a reduced RF power of 1.75 kW, down from 3 kW previously.
• The new configuration, featuring a more open structure and stronger plasma separation, led to higher production efficiency.
• Observed a higher flux of ro-vibrationally excited molecules and improved potential control near the extraction region.

Conclusions:

• The permanent magnet filter field design significantly enhances the production efficiency of the RF-driven H- ion source.
• The upgraded ion source is a promising replacement for the existing filament-driven source at the MCC30/15 cyclotron, offering improved performance at lower power consumption.