ECR ion source

The Electron Cyclotron Resonance (ECR) source

The ECR source consists of a ceramic plasma chamber located in a homogeneous magnetic field of about 87.5 mT provided by permanent magnets. A 2.45 GHz standard microwave generator provides typically 350W of microwave power from the backside while the front points towards the extraction system. An additional coil around the chamber allows to fine-tune the magnetic field to precisely match the ECR resonance condition. In resonance, free electrons are heated by the microwave-field. The hot electrons dissociate and/or ionize the hydrogen gas, which is continously fed into the plasma chamber.

The complete ion source assembly is on a 60 kV-high-voltage platform. Positively charged ions (H+, H2+ and H3+) are dragged out and focused by the potential difference of the extraction system.

ECR ion source
CAD drawing of the ECR ion source.
ECR proton source
The compact permanent magnet ECR ion source in the center. The microwave power is transported to the plasma chamber by a wave-guide (black). A so-called "DC-Blocker" insulates the high DC voltage of the ECR source from the wave-guide.
ECR Ion Source Beam
Residual gas allows to make the beam extracted from ECR Ion source visible. For this photo the gas pressure was raised to about 1E-5 mbar by additional gas let into the vacuum chamber.
Schematic drawing of the ECR proton source
Schematic drawing of the ECR proton source

Reference: https://pubs.aip.org/aip/rsi/article/82/5/053304/852552/A-compact-elect…