Kinetic energy offsets for multicharged ions from an electron beam ion source

Area of Science:

• Atomic and Molecular Physics
• Plasma Physics
• Ion Source Technology

Background:

• Electron Beam Ion Sources (EBIS) are crucial for generating multicharged ions.
• Accurate kinetic energy measurements of extracted ions are vital for many applications.
• Space charge effects within ion sources can influence ion beam properties.

Purpose of the Study:

• To quantify kinetic energy offsets in multicharged ions extracted from an EBIS.
• To investigate the relationship between electron beam space charge and ion kinetic energy shifts.
• To explore the utility of these energy offsets for characterizing the electron beam.

Main Methods:

• Utilized a retarding field analyzer to measure ion kinetic energies.
• Systematically varied electron beam current and energy to alter space charge density.
• Analyzed kinetic energy offsets for Argon ions (Ar4+ and Ar8+).

Main Results:

• Measured significant kinetic energy offsets between nominal and actual ion energies.
• Attributed these offsets to the trapping potential generated by electron beam space charge.
• Demonstrated a correlation between electron beam parameters, space charge, and energy offsets.

Conclusions:

• Electron beam space charge in EBIS directly impacts the kinetic energy of extracted multicharged ions.
• Understanding and quantifying these energy offsets is essential for applications requiring low-energy, high-potential-energy ions, such as surface modification.
• The measured kinetic energy offsets provide a method for estimating the electron beam's effective radius within the ion source.