Author: Eduard Chyhyrynets

Herstellung von Supraleitenden Duennen V3Si Filmen Durch DC Magnetron Sputtering-Foreign Institute Thesis Klaus Schirmer

Author: Klaus Schirmer ; Type of thesis: Foreign Institute Thesis
Abstract: The TESLA linear Collider would rely on superconducting structures at 1,3 GHz with a gradient of 25 MV/m and an unloaded quality factor at temperatures of 2 K. However Nb Technology asks for superfluid e cooling systems. The use of a higher critical temperature superconductors would allow to adopt the simpler 4,2 K cryogenics. V3Si has a reported Tc value of 17 K and RRR values up to 80 …. it follows –> Continue reading →

Herstellung von Supraleitenden Duennen V3Si Filmen Durch DC Magnetron Sputtering – Klaus Schirmer

Data: 10/01/1998
Abstract: The TESLA linear Collider would rely on superconducting structures at 1,3 GHz with a gradient of 25 MV/m and an unloaded quality factor at temperatures of 2 K.
However Nb Technology asks for superfluid e cooling systems. The use of a higher critical temperature superconductors would allow to adopt the simpler 4,2 K cryogenics.
V3Si has a reported Tc value of 17 K and RRR values up to 80 …. it follows –>

Author: Klaus Schirmer

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Sputtering niobium films into a RFQ model & Sputtering of superconducting V3Si film-Foreign Institute Thesis ZHANG YAN

Author: ZHANG YAN ; Type of thesis: Foreign Institute Thesis
Abstract: Superconducting technique has been widely applied to linac particle accelerators for more than two decades. Cryogenic RF performance of SC cavities has been improved a lot due to improvement on purification of SC material, as well as SC cavity design, fabrication and surface treatment techniques. The Sputtering technique of SC cavities provided another chance to particle accelerators: the cost of cavity fabrication greatly decreased, while the performances of sputtering coated niobium cavities are competitive with those of bulk material SC cavities.
In this thesis some important features of RF cavities are briefly introduced; the difference in design of a SC cavity and that of a normal conducting cavity are indicated. The design parameters of a 144 MHz SC QWR and an 1.5GHz monocell spherical cavity are presented. The SC material for cavity fabrication, and measurement method of SC cavity are introduced, then the fabrication and surface treatment technique of SC cavities are discussed.
The application of sputtering technique in SC cavities is a recent development of SRF technique. After nearly two decades study, the sputtering coated niobium film SC cavities achieved a cryogenic RF performance close to that of bulk niobium cavities. The thesis introduced various sputtering techniques on this purpose from preliminary glow discharge, discusses the LNL, Peking University and Australia National University’s QWR sputtering configurations, and introduces LNL’s surface treatment technique for copper substrate cavity.
In the study of niobium sputtering for 1.5GHz monocell spherical cavity, different magnetron configurations were tried and measured a large amount of sputtered niobium samples. By improving the magnetron configuration and surface treatment technique of the substrate cavity, sputtered niobium cavities with better RF performance were obtained. It was found out that substrate surface treatment takes a very important role in the sputtering of a SC cavity, as sample measurement cannot give out helpful information of the RF performance, the study with substrate Continue reading →

Sputtern von Supraleitundem Duennen Filmen fuer Radiofrequenz Beschleuigungsresonatoren-Foreign Institute Thesis JUERGEN BRODERS

Author: JUERGEN BRODERS ; Type of thesis: Foreign Institute Thesis
Abstract: A cylindrical postmagnetron has been designed for sputtering Niobium films into 1,5 Ghz monocell Copper cavities of the TESLA-type.
For sputtering 1.5 GHz monocells we built a cylindrical post-magnetron . The idea under such a design was the search of high sputtering rates and high thickness uniformity of the coating sampled along the cavity profile. Higher sputtering rates respect to classical cylindrical magnetron are possible when sputtering from the whole target surface. The advantage is twofold: the fraction of impurities trapped in the film linearly decreases versus deposition rate, moreover the deposition takes shorter time.
On the other side for the classical cylindrical magnetron, when the discharge is switch on, plasma do not live simultaneously on the whole target surface, instead it is strictly confined onto the target surface portion where ionizing electrons are trapped by magnetic field lines. A large portion of target surface, the one just outside of the magnetic trap, reaches high temperatures as well, but there is not sputtering from it, unless the electromagnet is moved toward this region.
On the basis of our experience on cylindrical magnetrons of such a design, we have observed that films untouched by plasma have systematically worse purity than films immersed in the discharge. This problem becomes not important for postmagnetrons,since the whole target surface is sputtered simultaneously. When designing a post-magnetron two choiceswere possible: a) the cathode must follow the profile of the cavity, keeping the magnetic field lines constantly parallel to the target. End losses being avoided by an electrostatic mirror outside of the cavity. In this case the shape of the target is rather complicated since to get into the narrow bore of the cutoff,it must be collapsible. b) the cathode is a straight tube and
the magnetic field follows the shape of the cavity. Continue reading →