ECR Ion Source
The ECR ion source was the first source built at the 88-Inch Cyclotron, and replaced the Penning Ion Gauge. It was designed and built by Claude Lyneis and Yves Jongen, delivering the first beam through the Cyclotron in January 1984.
The original ECR chamber, constructed of copper, was replaced in 2001 by an aluminum oxide chamber for greater secondary electron production properties, and to reduce the copper contamination of beams. The chamber is approximately 2 liters in volume; 33 cm in length by 9 cm inner diameter. The pumping is accomplished through 6 radial slots in the chamber using diffusion pumps. The source is typically run at an extraction voltage of 10 kV.
The ECR utilizes an injection stage at the front end of the plasma chamber. In this stage, a smaller plasma is created using 8.6 GHz microwaves at low power. This smaller plasma then flows into the main plasma chamber directly on axis. This helps to initiate and sustain the plasma in the main chamber. In later ECR designs, such as the AECR, this first stage was replaced by a metal disc at a negative bias relative to the plasma chamber.
Electron heating in the main plasma chamber is accomplished using 6.4 GHz microwaves. The RF power is typically run between 200 to 600 Watts depending on the desired ion production.
The ECR uses Nd-Fe permanent magnets in a hexapole structure, and room temperature solenoid coils for magnetic confinement of the ions. The original permanent magnets were Sm-Co. The solenoid magnets were upgraded, and the Sm-Co was replaced in 2001.
Materials can be introduced into the chamber directly through gas lines, MIVOC, by a radial probe, or using the two high temperature ovens and one low temperature oven. Access for the ovens and the probe is through the radial slots in the hexapole structure and chamber.