A. Kallenbach
A5025537611- Magnetic confinement fusion research
- Fusion materials and technologies
- Ionosphere and magnetosphere dynamics
- Superconducting Materials and Applications
- Particle accelerators and beam dynamics
- Nuclear reactor physics and engineering
- Laser-Plasma Interactions and Diagnostics
- Plasma Diagnostics and Applications
- Nuclear Materials and Properties
- Solar and Space Plasma Dynamics
- Atomic and Molecular Physics
- Nuclear Physics and Applications
- Laser-induced spectroscopy and plasma
- Gas Dynamics and Kinetic Theory
- High-Energy Particle Collisions Research
- Atomic and Subatomic Physics Research
- Spacecraft and Cryogenic Technologies
- Cold Atom Physics and Bose-Einstein Condensates
- Catalytic Processes in Materials Science
- Particle Accelerators and Free-Electron Lasers
- Quantum optics and atomic interactions
- Metallurgical Processes and Thermodynamics
- High-pressure geophysics and materials
- Radiative Heat Transfer Studies
- Semiconductor materials and devices
Max Planck Institute for Plasma Physics
2016-2025
Max Planck Society
2012-2021
Royal Military Academy
2020
Max Planck Innovation
1993-2012
Instituto Superior Técnico
1996
Leibniz University Hannover
1986-1989
Hanover College
1987
Progress, since the ITER Physics Basis publication (ITER Editors et al 1999 Nucl. Fusion 39 2137–2664), in understanding processes that will determine properties of plasma edge and its interaction with material elements is described. Experimental areas where significant progress has taken place are energy transport scrape-off layer (SOL) particular anomalous scaling, particle SOL plays a major role diverted plasmas main-chamber elements, localized mode (ELM) deposition on mechanism for ELM...
A multi-machine database for the H-mode scrape-off layer power fall-off length, λq in JET, DIII-D, ASDEX Upgrade, C-Mod, NSTX and MAST has been assembled under auspices of International Tokamak Physics Activity. Regression inside finds that most important scaling parameter is poloidal magnetic field (or equivalently plasma current), with decreasing linearly increasing Bpol. For conventional aspect ratio tokamaks, regression , yielding λq,ITER ≅ 1 mm baseline inductive burning scenario at Ip...
First experiments with nonaxisymmetric magnetic perturbations, toroidal mode number $n=2$, produced by newly installed in-vessel saddle coils in the ASDEX Upgrade tokamak show significant reduction of plasma energy loss and peak divertor power load associated type-I edge localized modes (ELMs) high-confinement plasmas. ELM mitigation is observed above an density threshold obtained both perturbations that are resonant not safety factor profile. Compared unperturbed ELMy reference plasmas,...
A future fusion reactor is expected to have all-metal plasma facing materials (PFMs) ensure low erosion rates, tritium retention and stability against high neutron fluences. As a consequence, intrinsic radiation losses in the edge divertor are comparison devices with carbon PFMs. To avoid localized overheating divertor, low-Z medium-Z impurities be inserted into convert major part of power flux facilitate partial detachment. For burning conditions ITER, which operates not far above L–H...
Detachment of high power discharges is obtained in ASDEX Upgrade by simultaneous feedback control core radiation and divertor or thermoelectric currents the injection radiating impurities. So far 2/3 ITER normalized heat flux Psep/R = 15 MW m−1 has been under partially detached conditions with a peak target well below 10 m−2. When detachment further pronounced towards lower at target, substantial changes edge localized mode (ELM) behaviour, density distribution occur. The time-averaged both...
The tungsten programme in ASDEX Upgrade is pursued towards a full high-Z device. spectroscopic diagnostic of W has been extended and refined the cooling factor re-evaluated. coated surfaces now represent fraction 65% all plasma facing components (24.8 m2). only two major that are not yet strikepoint region lower divertor as well limiters at low field side. While extending surfaces, concentration discharge behaviour have changed gradually pointing to critical issues when operating with wall:...
In ASDEX Upgrade, experimental efforts aim to establish pace making and mitigation of type-I edge localized modes (ELMs) in high confinement mode (H-mode) discharges. Injection small size cryogenic deuterium pellets (∼(1.4 mm)2 × 0.2 mm ≈ 2.5 1019 D) at rates up 83 Hz imposed persisting ELM control without significant fuelling, enabling for investigations well inside the regime. The approach turned out meet all required operational features. was realized with driving frequency ranging from 1...
Feedback control of the divertor power load by means nitrogen seeding has been developed into a routine operational tool in all-tungsten clad ASDEX Upgrade tokamak. For heating powers above about 12 MW, its use become inevitable to protect tungsten coating under boronized conditions. The is accompanied improved energy confinement due higher core plasma temperatures, which more than compensates negative effect dilution on neutron rate. This paper describes technical details feedback...
Recent research in scrape-off layer (SOL) and divertor physics is reviewed; new existing data from a variety of experiments have been used to make cross-experiment comparisons with implications for further ITER. Studies the region near separatrix addressed relationship profiles turbulence as well scaling parallel power flow. Enhanced low-field side radial transport implicated driving flows inboard side. The medium-n nature edge localized modes (ELMs) has elucidated measurements determined...
The first stable completely detached H-mode plasma in the full tungsten ASDEX Upgrade has been achieved. Complete detachment of both targets is induced by nitrogen seeding into divertor. Two new phases are added to classification described Potzel et al (2014 Nucl. Fusion 54 013001): first, line integrated density increases about 15% with partial outer Second, complete correlated appearance intense, strongly localized, radiation at X-point. Radiated power fractions, frad, increase from 50%...
Operation of DEMO in comparison to ITER will be significantly more demanding, as various additional limitations physical and technical nature have respected. In particular a set extremely restrictive boundary conditions on divertor operation during between ELMs It is high importance describe these order consider them early possible the ongoing development concept design. This paper extrapolates existing physics basis power particle exhaust DEMO.
Future fusion reactors require a safe, steady state divertor operation. A possible solution for the power exhaust challenge is detached operation in scenarios with high radiated fractions. The radiation can be increased by seeding impurities, such as N dominant scrape-off-layer radiation, Ne or Ar SOL and pedestal Kr core radiation. Recent experiments on two of all-metal tokamaks, ASDEX Upgrade (AUG) JET, demonstrate fractions fully-detached N, conventional vertical target geometry. For both...
Abstract A double radiative feedback technique has been developed on the ASDEX Upgrade tokamak for optimization of power exhaust with a standard vertical target divertor. The main chamber radiation is measured in real time by subset three foil bolometer channels and controlled argon injection outer midplane. heat flux addition nitrogen divertor private region using either thermoelectric sensor or scaled obtained channel No negative interference two controllers observed so far. combination...
With WEST (Tungsten Environment in Steady State Tokamak) (Bucalossi et al 2014 Fusion Eng. Des. 89 907–12), the Tore Supra facility and team expertise (Dumont Plasma Phys. Control. 56 075020) is used to pave way towards ITER divertor procurement operation. It consists implementing a configuration installing ITER-like actively cooled tungsten monoblocks tokamak, taking full benefit of its unique long-pulse capability. user platform, open all partners. This paper describes physics basis WEST:...
The plasma diagnostic and control (D&C) system for a future tokamak demonstration fusion reactor (DEMO) will have to provide reliable operation near technical physics limits, while its front-end components be subject strong adverse effects within the nuclear high temperature environment. ongoing developments ITER D&C represent an important starting point progressing towards DEMO. Requirements detailed exploration of are however pushing design using sophisticated methods aiming large spatial...
Abstract Future fusion reactors require a safe, steady state divertor operation. The required detached operation is, in tokamaks with metal walls, usually achieved by seeding of impurities, such as nitrogen. With strong levels, the dominant radiation is emitted from small, poloidally localized volume inside confined region, vicinity X-point. location radiating observed to vary relative X-point depending on and power i.e. degree detachment. At ASDEX Upgrade tokamak, position radiator can be...
Abstract Since the publication of review Progress in ITER Physics Basis (PIPB) 2007, significant progress has been made understanding processes at plasma-material interface. This review, part ITPA Nuclear Fusion Special Issue On Path to Burning Plasma Operation , presents these developments, focusing on key areas such as physics plasma exhaust, interactions, and properties plasma-facing materials their evolution under exposure. The coordinated efforts Topical Group Scrape-Off Layer Divertor...
The paper describes the effect of isotopic mass on plasma parameters as observed in ASDEX tokamak. comprises Ohmic well L mode, H mode and H* scenarios. measurements reveal that ion is a substantial robust parameter, which affects all confinement times (energy, particle momentum) whole operational window. Both core properties such sawtooth repetition time edge separatrix density change with mass. Specific emphasis given to changes due different types wall conditioning, carbonization...
Feedback-controlled puffing of neon and deuterium has been applied to control the edge-localized-mode behavior target plate power deposition during high-power $H$-mode discharges in ASDEX Upgrade. A regime found which more than 90% heating is lost through radiation divertor detachment occurs, without deterioration energy confinement. The plasma remains $H$ mode, exhibiting small-amplitude, high-frequency ELM's, do not penetrate plates strike zone region.
We present the results of experiments in JET to study effect plasma shape on high density ELMy H-modes, with geometry magnetic boundary similar that envisaged for standard Q = 10 operation ITER. The described are single lower null plasmas, q profile, neutral beam heating and gas fuelling, average triangularity δ calculated at separatrix ~0.45-0.5 elongation κ~1.75. In agreement previous obtained other divertor Tokamaks, thermal energy confinement time maximum achievable steady state a given...
In the ASDEX Upgrade tokamak, power deposition structures on divertor target plates during type-I edge localized modes (ELMs) have been investigated by infrared thermography. addition to axisymmetric strike line, several poloidally displaced stripes are resolved, identifying an ELM as a composite of subevents. This pattern is interpreted being signature helical perturbations in low field side non-linear evolution. Based this observation, related magnetic perturbation midplane can be derived...