Beam formation by ion optical system with slit finite length apertures

Area of Science:

• Plasma Physics
• Ion Optics
• Fusion Energy Engineering

Background:

• Effective ion beam formation is critical for plasma diagnostics in fusion reactors.
• Previous methods faced challenges with precise control and minimizing divergence.
• The Wendelstein 7-X stellarator requires advanced diagnostic tools for plasma analysis.

Purpose of the Study:

• To investigate the feasibility of accurate ion beam formation using a four-electrode ion optical system with finite slit apertures.
• To evaluate the performance of slit apertures with semicircular ends for beam control.
• To determine the suitability of this system for diagnostic neutral injectors.

Main Methods:

• Numerical simulations using 2D and 3D codes to model ion beam behavior.
• Experimental studies of beam formation in a single slit ion optical system.
• Measurement of angular beam divergences across and along the slit.

Main Results:

• Numerical simulations confirmed accurate ion beam formation with slit apertures featuring semicircular ends.
• Experimental measurements showed low angular beam divergences: 0.53 degrees across the slit and 0.35 degrees along the slit.
• The designed slit ion optical system is capable of precise ion beam shaping.

Conclusions:

• The four-electrode ion optical system with finite slit apertures enables accurate ion beam formation.
• The demonstrated low divergence is suitable for applications like diagnostic neutral injectors.
• This technology is directly applicable to enhancing diagnostic capabilities in large stellarators such as W-7X.