Study of dissipation in superconductors at high frequency regime
Description
This thesis is devoted to the study of the Joule effect dissipation occurring in superconducting accelerating cavities. Two mechanisms of dissipation are presented: the first concerns the magnetic flux present around the cryostat and trapped by the (Niobium) superconducting cavity during a temperature descent; a theoretical and experimental study allow the evaluation of the percentage of flux which rests trapped and its contribution to the dissipation. Improving the magnetic shielding leads to a remnant field of the order of several milli-Gauss and the surface resistance drops from 25 nΩ to 4.2 nΩ (with a few other modifications). The second mechanism is related to the polycrystalline structure of the superconductor. A theoretical study evaluates this contribution to about 3 nΩ. A complex process of recrystallization is needed in order to overcome this effect. Using an electron beam at low energy might help in reaching this goal and thus observing surface resistance values smaller than ever obtained. (author)
Abstract (French)
Cette these est consacree a l'etude de la dissipation par effet Joule survenant dans les cavites acceleratrices supraconductrices. Deux mecanismes sont ici etudies: le flux magnetique present autour du cryostat et piege par la cavite supraconductrice (en Niobium) lors de la descente en temperature; une etude theorique puis experimentale permet d'evaluer le pourcentage de flux qui reste piege et la contribution a la dissipation. Une amelioration du blindage conduisant a un champ remanent de l'ordre du milliGauss (et quelques autres modifications) permet de faire passer la resistance de surface de 25 nΩ a 4,2 nΩ. Le second mecanisme est lie a la structure polycristalline du supraconducteur. Une etude theorique evalue sa contribution a 3 nΩ environ. S'affranchir de cet effet passe par une recristallisation qui s'avere etre complexe. Cependant, l'utilisation d'un faisceau d'electrons de basse energie pourra peut-etre atteindre ce but et permettre d'obtenir des valeurs de resistance de surface encore jamais atteintes. (auteur)Files
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Additional details
Additional titles
- Original title (French)
- Etude de la dissipation dans les supraconducteurs en regime haute frequence
Identifiers
Publishing Information
- Imprint Pagination
- 175 p.
- Report number
- FRCEA-TH--6462
INIS
- Country of Publication
- France
- Country of Input or Organization
- France
- INIS RN
- 46122958
- Subject category
- S75: CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY;
- Resource subtype / Literary indicator
- Thesis
- Descriptors DEI
- COOLING; CRYOSTATS; CRYSTAL STRUCTURE; DISSIPATION FACTOR; ELECTRIC CONDUCTIVITY; ELECTROMAGNETISM; ELECTRON BEAMS; JOULE HEATING; MAGNETIC FLUX; MAGNETIC SHIELDING; NIOBIUM; POLYCRYSTALS; RECRYSTALLIZATION; SUPERCONDUCTING CAVITY RESONATORS; SUPERCONDUCTIVITY; SUPERCONDUCTORS
- Descriptors DEC
- BEAMS; CAVITY RESONATORS; CONTROL EQUIPMENT; CRYSTALS; DIMENSIONLESS NUMBERS; ELECTRIC CONDUCTIVITY; ELECTRIC HEATING; ELECTRICAL PROPERTIES; ELECTRONIC EQUIPMENT; ELEMENTS; EQUIPMENT; HEATING; LEPTON BEAMS; MAGNETISM; METALS; PARTICLE BEAMS; PHYSICAL PROPERTIES; PLASMA HEATING; REFRACTORY METALS; RESONATORS; SHIELDING; SUPERCONDUCTING DEVICES; THERMOSTATS; TRANSITION ELEMENTS
Optional Information
- Notes
- 72 refs.; Available from the INIS Liaison Officer for France, see the 'INIS contacts' section of the INIS website for current contact and E-mail addresses: http://www.iaea.org/inis/Contacts/
- Secondary number(s)
- DAPNIA-SEA--94-08