A low energy ion source for electron capture spectroscopy.

Area of Science:

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

Background:

• Low-energy ion beams are crucial for various applications, including surface science and materials modification.
• Existing ion sources often struggle to produce stable, low-energy beams with controllable charge states.
• Helium ions, in particular, are valuable for specific research and industrial processes.

Purpose of the Study:

• To design and characterize a versatile ion source capable of producing single and double charged helium ions.
• To achieve tunable kinetic energies for these ions, ranging from 5 eV to 300 eV.
• To optimize the ion source for high beam currents and explore the production of metastable helium ions.

Main Methods:

• Modification of a commercial sputter ion gun by integrating a Wien filter for mass/charge separation.
• Implementing a retardation system within the existing lens structure to achieve low ion energies without altering original components.
• Characterizing beam currents and energy distributions for He+ and He2+ ions at various operating parameters.

Main Results:

• The designed ion source successfully produces single (He+) and double (He2+) charged helium ions with energies from 5 eV to 300 eV.
• Achieved beam currents include up to 30 nA for He+ at 15 eV and significant currents for He2+ (320 pA at 30 eV, 46 pA at 5 eV).
• Operating parameters allow for optimization, including a notable contribution of metastable He*(+) (2s) ions.

Conclusions:

• The modified sputter ion gun provides a flexible and effective method for generating low-energy helium ion beams.
• The design demonstrates the capability to produce beams with specific charge states and energies suitable for advanced applications.
• Further optimization can enhance the yield of metastable helium ions, expanding the source's utility.