Compact Radiative Divertor Experiments at ASDEX Upgrade and Their Consequences for a Reactor

Area of Science:

• Nuclear Fusion Energy
• Plasma Physics
• Divertor Physics

Background:

• Magnetic confinement fusion faces challenges managing high exhaust power loads on divertor targets.
• Existing divertor concepts struggle with intense heat fluxes, risking component damage and operational instability.

Purpose of the Study:

• To introduce and experimentally validate a novel compact radiative divertor (CRD) concept for fusion power exhaust.
• To assess the CRD's effectiveness in dissipating power via radiation before it reaches divertor targets.

Main Methods:

• Utilized the ASDEX Upgrade tokamak for high-performance experiments.
• Established an X-point radiator upstream of the divertor targets to create a cold, dense radiating plasma.
• Monitored target plate temperatures with an IR camera during high heating power (15 MW).

Main Results:

• No hot spots were observed on target plates despite shallow field line incidence angles (0.2°).
• Stable plasma confinement (H98,y2=1) and divertor detachment were achieved without feedback control.
• The CRD concept demonstrated feasibility under high heating power conditions.

Conclusions:

• The CRD concept is a technically simple and effective solution for fusion power exhaust.
• CRD technology shows promising scalability to reactor-sized fusion devices.
• Potential benefits include increased plasma volume, space for breeding blankets, and improved vertical stability.