A mid-size tokamak at Germany’s Max Planck Institute for Plasma Physics that pioneered the all-tungsten first wall and remains a leading facility for ITER-relevant confinement research.
ASDEX Upgrade (Axially Symmetric Divertor Experiment) is a mid-size divertor tokamak operated by the Max Planck Institute for Plasma Physics (IPP) in Garching, near Munich, Germany. It began operation in 1991 as the successor to ASDEX, the device on which Friedrich Wagner and colleagues discovered the high-confinement mode (H-mode) in 1982—one of the most consequential findings in fusion plasma physics.[1] ASDEX Upgrade was designed to investigate divertor physics, plasma-wall interaction, and advanced confinement scenarios in an ITER-like geometry.
ASDEX Upgrade uses conventional copper coils and features a single-null divertor geometry closely matching the shape and aspect ratio of ITER (R/a ≈ 3.3). Its moderate size allows rapid experimental turnaround while maintaining plasma parameters relevant to reactor-scale physics. The heating suite—neutral beam injection, electron cyclotron resonance heating (ECRH), and ion cyclotron resonance heating (ICRH)—provides approximately 27 MW of combined power, enabling access to high-performance regimes at reactor-relevant heating power densities.[2]
ASDEX Upgrade’s most distinctive contribution has been its systematic, stepwise transition to an all-tungsten first wall—completed by 2007—making it the first large tokamak to operate with full tungsten plasma-facing components. This is a verified engineering and physics result: the tungsten program demonstrated that high-Z metal walls are compatible with high-performance H-mode plasmas, provided that impurity control techniques (such as central ECRH) are employed to prevent tungsten accumulation in the plasma core.[3] These findings directly informed the ITER decision to adopt a tungsten divertor and have provided essential operational experience for future reactor wall design.
Beyond the tungsten program, ASDEX Upgrade has contributed to ELM mitigation research (including magnetic perturbation experiments and pellet-pacing techniques), the development of scenarios with improved energy confinement at reduced ELM activity, and the study of plasma exhaust and detachment in reactor-relevant geometries. Its diagnostic suite is among the most comprehensive on any tokamak, supporting detailed profile and fluctuation measurements.[2]
The device has also played a key role in developing integrated plasma scenarios that combine good confinement, controlled impurities, and acceptable heat loads—the combination that a reactor must sustain simultaneously.
As of 2026, ASDEX Upgrade continues to operate as a principal European facility for fusion plasma research under the EUROfusion consortium. It has undergone successive upgrades to its ECRH capacity and divertor geometry and remains a primary tool for preparing the physics and operational basis for ITER.[2]