A5064211539- Particle accelerators and beam dynamics
- Plasma Diagnostics and Applications
- Magnetic confinement fusion research
- Particle Accelerators and Free-Electron Lasers
- Atomic and Molecular Physics
- High voltage insulation and dielectric phenomena
- Ammonia Synthesis and Nitrogen Reduction
- Magnetic Field Sensors Techniques
- Fusion materials and technologies
- Hydrogen Storage and Materials
- Metal and Thin Film Mechanics
- Muon and positron interactions and applications
- Superconducting Materials and Applications
- Laser-induced spectroscopy and plasma
- Semiconductor materials and devices
- Electron and X-Ray Spectroscopy Techniques
- Spacecraft and Cryogenic Technologies
- Analytical Chemistry and Sensors
- Chemical Reactions and Isotopes
- Mass Spectrometry Techniques and Applications
- Gas Dynamics and Kinetic Theory
Max Planck Institute for Plasma Physics
2018-2025
University of Augsburg
2019-2022
Max Planck Society
2018-2020
Fraunhofer Institute for Ceramic Technologies and Systems
2020
Augsburg University
2019
The neutral beam injection systems for the international fusion experiment ITER used heating, current drive, and diagnostic purposes are based on RF-driven negative hydrogen ion sources with a source area of roughly 0.9 m × 1.9 m. operate at 0.3 Pa in deuterium using total available RF generator power 800 kW per frequency 1 MHz. In order to fulfill challenging requirements beyond (like DEMOnstration plant, DEMO), worldwide developments underway addressing topics plasma generation, extraction...
Abstract Since negative hydrogen ion sources for neutral beam injection (NBI) systems rely on the surface production of ions, Cs is injected to lower work function extraction electrode surface. The adsorbed layers are affected by residual gases from given non-UHV conditions as well reactive species during plasma phases, which leads a complex chemistry and occurrence temporal changes function. To control get insight into its dynamics, an absolute diagnostic has been developed with...
Abstract ITER’s NBI systems are a first of its kind system with very challenging targets for the RF-driven ion source and acceleration stage. In step ladder approach, test facilities BATMAN Upgrade (BUG) ELISE support activities carried out at Neutral Beam Test Facility, Padua, which is equipped facility SPIDER MITICA being equivalent to ITER Heating injector (HNB), capable operating full power pulse length HNBs. The contributions prototype BUG (1/8 scale) size scaling experiment (1/2...
Abstract Modern high-power negative hydrogen ion sources rely predominantly on the surface production of ions. Hence, low work function converter surfaces are mandatory, for which alkali metal Cs is commonly evaporated into source to lower refractory metals by adsorption. To study behaviour upon caesiation under typically given non-ultra-high vacuum conditions, investigations performed at a dedicated laboratory experiment. In environment dominated water vapour, evolution found be dependent...
The surface production of negative hydrogen ions requires low work function (WF) converter surfaces, for which caesium adsorption is typically used. Since highly reactive and easily forms compounds, the resulting WF strongly influenced by vacuum conditions, ranging from about 10−8 to 10−6 mbar in present-day ion sources accelerators fusion. As water usually main residual gas, dedicated investigations on evolution upon coadsorption are performed. conducted an ultra-high chamber (base pressure...
Abstract Negative hydrogen or deuterium ion sources for neutral beam injection (NBI) systems used at fusion devices are based on the surface production process a caesiated low work function converter surface. While producing stable and globally homogeneous negative is not an issue, during long pulses typically pronounced increase in co-extracted electrons observed, limiting pulse length achievable performance. This effect particularly it attributed to increasing of In last years source test...
The exploitation of the photoelectric effect is a prominent method for in situ measurement absolute work function surface. In case metallic surfaces, Fowler theory routinely applied fitting or extrapolating measured yield data to determine value. However, reliable application method, attention must be paid experimental sensitivity behavior close threshold, which mainly determined by signal-to-noise ratio photocurrent detection and available photon energies used irradiation. This illustrated...
Abstract The neutral beam heating system for the future international fusion experiment ITER will be based on radio-frequency driven ion sources delivering a large (≈1 × 2 m ) and homogeneous negative hydrogen or deuterium of several ten Amperes hundred seconds. size scaling ELISE (Extraction from Large Ion Source Experiment) is an integral part R&D road-map towards system. Recently, 90% target extracted current density was achieved in 600 s, increasing pulse length over which such...
Abstract In negative hydrogen ion sources in situ adsorption of Cs is typically used to generate low work function converter surfaces. The achievement a temporally stable coating is, however, challenging due the plasma interaction with surface. Particularly for neutral beam injection systems fusion pulse durations minutes hours temporal instabilities are major issue and limit source performance. To clarify influence on surface, investigations performed at an experiment equipped absolute...
The calcium aluminate electride [Ca24Al28O64]4+(e−)4 (C12A7:e−) is chemically and thermally stable in ambient atmosphere, offers strong electron donating capabilities exhibits an intrinsic work function of 2.4 eV. Thus, it attractive material for emitter low applications. For implementation negative hydrogen ion sources, where the could serve as a converter surface H− production, compatibility with moderate vacuum conditions exposure to pressure temperature plasmas must be ensured. Hence,...
Abstract The large ion source of ITER’s neutral beam injection (NBI) systems (0.9 m×1.9 m) with 1280 apertures has to deliver 57 A D - for 3600 s (286 A/m 2 ) and 66 H 1000 (329 ). RF test facilities ELISE BUG at IPP are aimed demonstrate the parameters, homogeneity beams (up 1 m×1 perform optic studies. While ITER parameters could be demonstrated in hydrogen, achievement deuterium long pulses is still pending due fraction co-extracted electrons, their temporal dynamics, inhomogeneity...
The electron energy distribution function (EEDF) in low pressure plasmas is typically evaluated by using the second derivative d2I/dV2 of a Langmuir probe I–V characteristic (Druyvesteyn formula). Since measured characteristics are inherently noisy, two-time numerical differentiation requires data smoothing techniques. This leads to dependence on employed filtering technique, and information particularly region near plasma potential can easily get lost. As an alternative noisy data,...
In low pressure temperature plasmas (p ∼ Pa, Te eV) the upper levels of Balmer series hydrogen atom are populated by several excitation channels.While electron impact is dominant for so-called ionizing (Te → 10 eV), dissociative recombination (DR) via molecular ion H + 2 becomes in recombining 1 eV).In intermediate range, other channels may be relevant as well.The expansion region an ECR discharge, which represents such a plasma, analyzed regarding composition processes well line profiles...
<title>Abstract</title> In negative hydrogen ion sources in situ adsorption of Cs is typically used to generate low work function converter surfaces. The achievement a temporally stable coating is, however, challenging due the plasma interaction with surface. Particularly for neutral beam injection systems fusion pulse lengths minutes hours temporal instabilities are major issue and limit source performance. To clarify influence on surface, investigations performed at an experiment equipped...
The development of ion sources for NNBI systems at future fusion devices like ITER or DEMO is based on the surface production negative hydrogen ions. Thus, low work function converter surfaces are mandatory. Besides state-of-the-art technique continuous Cs injection during source operation, alternative materials desirable to overcome drawbacks volatile coatings. In this work, a C12A7 electride material studied regarding behavior in and deuterium plasma environment relevant conditions....
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