Analysis of voltage spikes in superconducting Nb3Sn magnets

Fermi National Accelerator Laboratory has been developing a new generation of superconducting accelerator magnets based on Niobium Tin (Nb{sub 3}Sn). The performance of these magnets is influenced by thermo-magnetic instabilities, known as flux jumps, which can lead to premature trips of the quench detection system due to large voltage transients or quenches at low current. In an effort to better characterize and understand these instabilities, a system for capturing fast voltage transients was developed and used in recent tests of R&D model magnets. A new automated voltage spike analysis program was developed for the analysis of large amount of voltage-spike data. We report results from the analysis of large statistics data samples for short model magnets that were constructed using MJR and RRP strands having different sub-element size and structure. We then assess the implications for quench protection of Nb{sub 3}Sn magnets

Magnet reliability in the Fermilab Main Injector and implications for the ILC

The International Linear Collider reference design requires over 13000 magnets, of approximately 135 styles, which must operate with very high reliability. The Fermilab Main Injector represents a modern machine with many conventional magnet styles, each of significant quantity, that has now accumulated many hundreds of magnet-years of operation. We review here the performance of the magnets built for this machine, assess their reliability and categorize the failure modes, and discuss implications for reliability of similar magnet styles expected to be used at the ILC

Active liquid crystal tuning of metallic nanoantenna enhanced light emission from colloidal quantum dots

A system comprising an aluminum nanoantenna array on top of a luminescent colloidal quantum dot waveguide and covered by a thermotropic liquid crystal (LC) is introduced. By heating the LC above its critical temperature, we demonstrate that the concomitant refractive index change modifies the hybrid plasmonic-photonic resonances in the system. This enables active control of the spectrum and directionality of the narrow-band (similar to 6 nm) enhancement of quantum dot photoluminescence by the metallic nanoantennas

Lichtemissie van roosters van nanoantennes

De koppeling van lichtbronnen (fluorescerende materialen) aan nanostructuren heeft een grote invloed op alle eigenschappen van de emissie: op de golflengte, richting, polarisatie en efficiëntie. Controle over deze emissie is relevant voor fundamenteel onderzoek naar de interactie op de nanoschaal tussen licht en materie, maar ook voor toepassingen die een brede impact op onze maatschappij kunnen hebben. Bij AMOLF en Philips Research onderzoeken wij roosters van metallische nanodeeltjes die collectieve resonanties vertonen. De emissie van lichtbronnen gekoppeld aan deze roosters kan hiermee versterkt worden in bepaalde richtingen. Dit biedt mogelijkheden voor efficiënte leds met geïntegreerde, gecollimeerde optiek op basis van nanostructuren. Roosters van nanodeeltjes vertonen ook onverwachte verschijnselen zoals de versterkingen van de lichtemissie van bronnen in de nabijheid van transparante roosters

Light-emitting waveguide-plasmon polaritions

We demonstrate the generation of light in an optical waveguide strongly coupled to a periodic array of metallic nanoantennas. This coupling gives rise to hybrid waveguide-plasmon polaritons (WPPs), which undergo a transmutation from plasmon to waveguide mode and vice versa as the eigenfrequency detuning of the bare states transits through zero. Near zero detuning, the structure is nearly transparent in the far-field but sustains strong local field enhancements inside the waveguide. Consequently, light-emitting WPPs are strongly enhanced at energies and in-plane momenta for which WPPs minimize light extinction. We elucidate the unusual properties of these polaritons through a classical model of coupled harmonic oscillators