ASDEX Upgrade is working on the principles for planning and operation of the ITER test reactor and is preparing for a follow-up demonstration power plant.
The aim of experimentation on ASDEX Upgrade is to clarify the behaviour of a magnetically confined tokamak plasma and numerically describe it. This applies particularly to the motion of particles in the magnetic cage, the stability of the plasma, and the exhaust of plasma and impurity particles into the divertor.
On the one hand, this involves more fundamental investigation and improvement of known modes of operation, as envisaged for ITER. On the other hand, new, more powerful operation scenarios for ITER, DEMO, and future fusion power plant are to be developed, viz. plasmas with higher energy content, improved stability, and longer pulse time.
The topics treated in ASDEX Upgrade include:
- particle and energy transport in the plasma, plasma turbulence
- divertor studies and power exhaust
- investigation of plasma instabilities
- development of optimised plasma scenarios that reconcile high plasma density and high plasma pressure with moderate edge instabilities
- testing of theoretical models in respect of divertor physics, turbulence, and plasma transport
- studies of wall materials
The ASDEX Upgrade device is particularly suited to these experiments by virtue of the power-plant-like geometry, the tungsten-clad vessel wall, and the powerful, flexible plasma heating. Its quality index P/R of 15 megawatts per square metre, i.e. the heating power P in relation to the plasma radius R, puts ASDEX Upgrade closer to ITER than all other devise world-wide.
Happy Birthday, ASDEX Upgrade!
Since start of operation 30 years ago, ASDEX Upgrade has explored the physics for a future fusion power plant in 38,812 plasmas, said project head Professor Arne Kallenbach in April 2021. (photo: elja)
Dr. Athina Kappatou is working at ASDEX Upgrade with spectroscopic measurements of helium and fast ions. “That’s why I sometimes work inside the plasma vessel, to maintain and calibrate the diagnostics”. (photo: Bernhard Ludewig)
Processing the measured values from the numerous diagnostics, 50 gigabytes per discharge, into computer-readable data and making it available for real-time evaluation and control of the plasma: That is the task of the Data Acquisition group. (photo: elja)
Operator Klaus Klöss ensures that the experiments at ASDEX Upgrade run smoothly. He checks the readiness of all systems: Power supply, plasma heating, pellet injector, ... His announcement "next shot" starts the plasma discharge. (photo: elja)
Michael Rott from the "Experimental Power Supply" group is responsible for providing the electrical energy required for ASDEX Upgrade - for magnetic coils and plasma heating systems - by using three large flywheel generators. (photo: elja)
Powerful circuit breakers made of copper transfer the electrical energy from the flywheel generators to the solenoid coils of ASDEX Upgrade. Isabell Hofer-Maksymiw and her colleagues are in charge of the fully automated control. (photo: Axel Griesch)
In his role as "chief engineer," plasma physicist Dr. Albrecht Herrmann and his team ensure that ASDEX Upgrade is running and keeps developing. Since its start 30 years ago, the facility has been continuously upgraded and improved. (photo: A. Griesch)
The "Tokamak Scenario Development" division is responsible for the operation of ASDEX Upgrade. The secretariat is where all the threads come together: Petra Jordan and her colleagues are the central contact for everyone and take care of events, business trips, schedules and the staff. (photo: elja)
The team “Neutral Particle Heating” - here grouped around the four ion sources of an injector – ensures getting up the plasma to temperature. The high-energy particle beams provide up to 20 megawatts, enough for 100 million degrees. (photo: A. Griesch)
The optical fibers of the helium beam diagnostics observe the plasma edge of ASDEX Upgrade: The light emitted by injected helium atoms during collisions with the electrons reveals their temperature and density to PhD student Daniel Wendler. (Photo: A. Griesch)
A large switch converts hydrogen gas into plasma: Fast rerouted currents provide a high voltage for a short time. Michael Schandrul of the "Operations Group" here in front of the power supplies for the switch's resistor. (photo: A. Griesch)
Prof. Dr. Elisabeth Wolfrum - here in the control room - has already supervised many doctoral theses on lithium beam diagnostics. The fast measuring device provides the profile of the electron density at the plasma edge every 50 microseconds. (photo: elja)
How to get a tokamak from pulsed to continuous operation? This is what Dr. Alexander Bock, who develops advanced tokamak scenarios, is investigating. He is also responsible for the interferometers used to measure the plasma density. (photo: Jan Schölzel)
In the pump room: Michaela Uhlmann, Anton Dollenbacher and Gerd Schall (from left) are responsible for the pumps that circulate the cooling water for the ASDEX Upgrade solenoid coils, the plasma vessel and the in-vessel components. (photo: Axel Griesch)
In the distribution room, engineer Benjamin Schmidt and his colleagues assign the institute's high-voltage systems to different consumers, such as the various plasma-heating systems. (Photo: Axel Griesch)
Doppler reflectometer: Dr. Tim Happel can measure turbulence in the plasma using microwaves irradiated into the plasma and scattered there. In this way, turbulence codes can be checked for planning future experiments. (photo: A. Griesch)
The division "Plasma Edge and Wall" studies plasma dynamics and plasma-wall interaction at ASDEX Upgrade. In the secretariat of the division Biggy Perey and her colleague take care of all organizational and administrative work. (photo: elja)
PhD student Antonio Magnanimo is developing a power supply prototype based on supercapacitors. Two thousand of the modules stacked on the right could replace the flywheel generator that supplies the magnets of ASDEX Upgrade (photo: A. Griesch).
With this device, engineer Matthias Peglau and his colleagues from the “Experimental Power Supply” group test components at up to 300 kV DC, but small currents of typically 100 mA to determine their electrical insulation strength. (photo: A. Griesch)
When Dr. Rachel McDermott is not acting as experiment leader, she studies how impurities behave in a plasma and guides the ASDEX Upgrade team through the work program here in the control room. (photo: Axel Griesch)
Norbert Berger and Alfred Kaltenberger from the Cryogroup take care of the helium liquification plant. It supplies the cryopump to create the high vacuum in the plasma vessel. Smallest amounts of gas freeze on the cold surfaces of the pump. (photo: A. Griesch).
The pellet generator, here disassembled, delivers cubes of hydrogen ice, which an injector shoots deeply into the plasma for refueling. Dr. Peter Lang, Bernhard Plöckl, Michael Beck and Jan Ufer are in charge of pellet physics and technology (photo: A. Griesch).
On the platform above the four high-frequency transmitters that supply the ASDEX Upgrade plasma with radio waves: Gerhard Siegl, Dr. Volodymyr Bobkov and Helmut Faugel (from left), surrounded by waveguides and the dismounted antenna (photo: A. Griesch)
Thomas Pirsch from the CODAC Group is also responsible for the interlock system as one of many control systems. During the start of a plasma discharge, it activates the heating systems when the density and current in the plasma reach the set values. (photo: A. Griesch)
PhD student Klara Höfler has just calibrated the Doppler reflectometer in the plasma vessel. The movable mirror of the measuring device transmits microwaves into the plasma to measure the turbulence and compare it with theoretical models. (photo: A. Griesch)
Microwave heating system: Erik von Werne and Gerhard Grünwald maintain a microwave source that generates a power of one megawatt. Directed via movable mirrors, the waves can improve plasma stability or shape the plasma current. (photo: Bernhard Ludewig)