0000000000056123

AUTHOR

M. Keunecke

showing 3 related works from this author

Cubic boron nitride: A new prospective material for ultracold neutron application

2009

Abstract At the ultracold neutron (UCN) source of the TRIGA research reactor in Mainz, we have measured for the first time the material optical wall-potential of cubic boron nitride. The measurements were performed with a time-of-flight (TOF) spectrometer. The samples investigated had a wall-potential of ( 305 ± 15 ) neV . This value is in good agreement with the result extracted from neutron reflectometry data and theoretical expectations. Because of its high critical velocity for UCN and its good dielectric characteristics, cubic boron nitride coatings (isotopically enriched) will be useful for a number of applications in UCN experiments.

PhysicsNuclear and High Energy PhysicsSpectrometerPhysics::Instrumentation and DetectorsFOS: Physical sciencesDielectricCritical ionization velocityTRIGACondensed Matter::Materials Sciencechemistry.chemical_compoundNuclear magnetic resonancechemistryBoron nitrideNeutronResearch reactorNeutron reflectometryNuclear Experiment (nucl-ex)Atomic physicsNuclear ExperimentNuclear ExperimentInstrumentation
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Major results from the first plasma campaign of the Wendelstein 7-X stellarator

2017

After completing the main construction phase of Wendelstein 7-X (W7-X) and successfully commissioning the device, first plasma operation started at the end of 2015. Integral commissioning of plasma start-up and operation using electron cyclotron resonance heating (ECRH) and an extensive set of plasma diagnostics have been completed, allowing initial physics studies during the first operational campaign. Both in helium and hydrogen, plasma breakdown was easily achieved. Gaining experience with plasma vessel conditioning, discharge lengths could be extended gradually. Eventually, discharges lasted up to 6 s, reaching an injected energy of 4 MJ, which is twice the limit originally agreed for t…

Magnetic confinementNuclear and High Energy PhysicsTechnology and EngineeringPlasma heatingCyclotron resonanceCONFINEMENT01 natural sciencesElectron cyclotron resonance010305 fluids & plasmaslaw.inventionPHYSICSNuclear physicsstellaratorcurrent drive; magnetic confinement; plasma heating; stellarator; Nuclear and High Energy Physics; Condensed Matter Physicslaw0103 physical sciencesddc:530010306 general physicstellaratorStellaratorPhysicsmagnetic confinementMagnetic confinement fusionplasma heatingcurrent drive;magnetic confinement;plasma heating;stellaratorPlasma530 PhysikCondensed Matter PhysicsTRANSPORTCurrent drivecurrent driveElectron temperaturePlasma diagnosticsAtomic physicsWendelstein 7-X[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]StellaratorNuclear Fusion
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Technical challenges in the construction of the steady-state stellarator Wendelstein 7-X

2013

The next step in the Wendelstein stellarator line is the large superconducting device Wendelstein 7-X, currently under construction in Greifswald, Germany. Steady-state operation is an intrinsic feature of stellarators, and one key element of the Wendelstein 7-X mission is to demonstrate steady-state operation under plasma conditions relevant for a fusion power plant. Steady-state operation of a fusion device, on the one hand, requires the implementation of special technologies, giving rise to technical challenges during the design, fabrication and assembly of such a device. On the other hand, also the physics development of steady-state operation at high plasma performance poses a challeng…

Nuclear and High Energy PhysicsSteady state (electronics)LIMIT ANALYSISPLASMANuclear engineeringMAGNET SYSTEMPlasmaFusion powerCondensed Matter PhysicsW7-XElectron cyclotron resonancelaw.inventionPHYSICSData acquisitionHeating systemlawWendelstein 7-XStellarator
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