Development of a reconstruction procedure for the halo current distribution

Area of Science:

• Plasma Physics
• Fusion Energy Engineering

Background:

• Magnetic confinement fusion devices rely on understanding plasma-wall interactions during disruptions.
• Halo currents (HC) generated during disruptions pose significant J x B loading risks to the vessel structure.
• Limited sensor placement on first wall modules provides only partial HC distribution data.

Purpose of the Study:

• To develop and implement a novel procedure for estimating the complete halo current distribution within toroidal machines.
• To overcome limitations of spatially discontinuous plasma-wall contact areas that hinder traditional harmonic function fitting.
• To enable accurate evaluation of J x B loads on vessel structures.

Main Methods:

• A procedure was developed to infer total injected currents from limited first wall current sensor measurements.
• The method was tested using a numerical machine model with simplified geometry.
• The technique is designed to handle complex and discontinuous HC distributions.

Main Results:

• The developed procedure successfully estimates the complete halo current distribution.
• Validation was performed on a numerical model, demonstrating the method's efficacy.
• The approach is shown to be applicable to complex HC distributions, including those in ITER.

Conclusions:

• The new procedure provides a viable solution for determining full halo current distribution in magnetic confinement devices.
• Accurate HC mapping is essential for mitigating structural damage from J x B forces.
• This technique is scalable and applicable to future fusion reactors like ITER.