2 results
Search Results
Now showing 1 - 2 of 2
- ItemVectorial calibration of superconducting magnets with a quantum magnetic sensor(Melville, NY : American Inst. of Physics, 2020) Botsch, L.; Raatz, N.; Pezzagna, S.; Staacke, R.; John, R.; Abel, B.; Esquinazi, P. D.; Meijer, J.; Diziain, S.Cryogenic vector magnet systems make it possible to study the anisotropic magnetic properties of materials without mechanically rotating the sample but by electrically tilting and turning the magnetic field. Vector magnetic fields generated inside superconducting vector magnets are generally measured with three Hall sensors. These three probes must be calibrated over a range of temperatures, and the temperature-dependent calibrations cannot be easily carried out inside an already magnetized superconducting magnet because of remaining magnetic fields. A single magnetometer based on an ensemble of nitrogen vacancy (NV) centers in diamond is proposed to overcome these limitations. The quenching of the photoluminescence intensity emitted by NV centers can determine the field in the remanent state of the solenoids and allows an easy and fast canceling of the residual magnetic field. Once the field is reset to zero, the calibration of this magnetometer can be performed in situ by a single measurement of an optically detected magnetic resonance spectrum. Thereby, these magnetometers do not require any additional temperature-dependent calibrations outside the magnet and offer the possibility to measure vector magnetic fields in three dimensions with a single sensor. Its axial alignment is given by the crystal structure of the diamond host, which increases the accuracy of the field orientation measured with this sensor, compared to the classical arrangement of three Hall sensors. It is foreseeable that the magnetometer described here has the potential to be applied in various fields in the future, such as the characterization of ferromagnetic core solenoids or other magnetic arrangements. © 2020 Author(s).
- ItemPreparation, analysis, and application of coated glass targets for the Wendelstein 7-X laser blow-off system(Melville, NY : American Inst. of Physics, 2020) Wegner, Th.; Geiger, B.; Foest, R.; Jansen van Vuuren, A.; Winters, V. R.; Biedermann, C.; Burhenn, R.; Buttenschön, B.; Cseh, G.; Joda, I.; Kocsis, G.; Kunkel, F.; Quade, A.; Schäfer, J.; Schmitz, O.; Szepesi, T.Coated glass targets are a key component of the Wendelstein 7-X laser blow-off system that is used for impurity transport studies. The preparation and analysis of these glass targets as well as their performance is examined in this paper. The glass targets have a high laser damage threshold and are coated via physical vapor deposition with μm thick films. In addition, nm-thin layers of Ti are used as an interface layer for improved ablation efficiency and reduced coating stress. Hence, the metallic or ceramic coating has a lateral homogeneity within 2% and contaminants less than 5%, being optimal for laser ablation processing. With this method, a short (few ms) and well defined pulse of impurities with about 1017 particles can be injected close to the last closed flux surface of Wendelstein 7-X. In particular, a significant amount of atoms with a velocity of about 1 km/s enters the plasma within 1 ms. The atoms are followed by a negligible concentration of slower clusters and macro-particles. This qualifies the use of the targets and applied laser settings for impurity transport studies with the laser blow-off system in Wendelstein 7-X. © 2020 Author(s).