Database Design for Superconducting Magnets

1. Database Design for Superconducting Magnets CERN Summer Student 2006 Tae-Joon Cho (Cambridge) Under supervision of Dr. Walter Scandale (CERN) Emanuele Laface (CERN)

2. Database design for superconducting magnets Contents • Magnets and Magnetic Field B • Superconductors • Parameters • Database survey and Collaborations • Conclusions • Bibliography • (History) Development of Superconductivity

3. Database design for superconducting magnets Magnets & Magnetic Field B • A magnet is an object that has a magnetic field. • Permanent magnets (Permagnets) & Electromagnets. e.g. Dipoles, Earth, Solenoids etc. • A magnetic field is that part of the electromagnetic field that exists when there is a changing electric field.

4. Database design for superconducting magnets ? Superconductors I Why • Superconductivity is a phenomenon occurring in certain materials at extremely low temperatures (~ a few K), characterized by exactly zero electrical resistance and the exclusion of the interior magnetic field (the Meissner effect) • Superconductivity  lim0(normal conductivity) • Superconductivity is a quantum mechanical phenomenon • Meissner effect  Faraday’s / Lenz’s Law • Applications • MRI, Particle Accelerators, etc. • A comparison of Magnetic Field Strengths • Dipole BD : T ~ mT • Earth’s BE : 30T ~ 60T • ATLAS BATLAS : ~ 2T • CMS BCMS : ~ 4T • A comparison of Typical Currents • Laptop : A ~ mA • A voltage source 220V, a resistance 220k  1mA  mag(B) ~ 2T, I ~ 10,000,000A  P ~ 1016kW • LHC requires ~ 12000A <Magnetic Levitation above a Superconductor> 103 ~ 105! http://www.cartoonstock.com

5. Database design for superconducting magnets Superconductors II Niobium Titanium (NbTi) • NbTi is a ductile Alloy • Superconductivity below the surface • Upper critical field Bc • Critical temperature c • Critical current density Jc(Bc,c) • First detailed study in 1961 (John K.Hulm and Richard D.Blaugher) from Westinghouse Research Laboratories in Pittsburgh, Pennsylvania) Main Parameters!

6. Database design for superconducting magnets Superconductors III • Niobium-Titanium (NbTi) • Detailed study in 1961 • Critical temperature ~ 9K at 0T • Niobium-Tin (Nb3Sn) • Detailed study in 1954 • Critical temperature ~ 18K at 0T • Brittle  Ductile  Filamentsx Coolant (liquid He ~ 4K)  Higher critical field B

7. Database design for superconducting magnets Parameters • Critical temperature c • Upper critical field Bc • Critical current density Jc (Bc, c) • Ductility • Phase transitions • Mechanical/Physical/Chemical properties  More than 100 parameters

8. Database design for superconducting magnets Database Survey http://sdb.web.cern.ch/sdb/

9. Database design for superconducting magnets Collaborations • LHC at CERN • Tevatron at FermiLab • HERA (Hadron-Electron Ring Accelerator) in Hamburg, Germany • FAIR at GSI in Frankfurt, Germany • ITER (International Thermonuclear Experimental Reactor) in France • J-PARC (Japan Proton Accelerator Research Complex) at KEK in Japan • KEKB (Electron-positron colliding-beam accelerator) in Tsukuba Campus at KEK in Japan • ILC (International Linear Collider project) at KEK in Japan

10. Database design for superconducting magnets Conclusions • Increasing demand on superconductors • More theoretical & experimental developments • R&D on Permanent magets • Recognition of main parameters • Inter-relations of those parameters • Collaborations • User friendly Database (Oracle SQL)

11. Database design for superconducting magnets Thank you for your attention! ?

12. Database design for superconducting magnets Bibliography • Superconducting Magnets –Chapter 12 & 13 • Martin N. Wilson (Oxford University Press) • Practical Low-Temperature Superconductors for Electromagnets • A. Devred (CERN Report 2004) • Superconducting magnet technology for particle accelerators and detectors • T. Taylor (CERN Summer Student Lecture, 14 July 2006) • Wikipedia (http://www.wikipedia.org/) http://sdb.web.cern.ch/sdb/

13. History Development of Superconductivity • In 1911, the group led by Heike Kammerling-Onnes(1853  1926, Netherlands) in a laboratory of Leiden University discovered superconductivity for the first time. • In 1933, Walter Meissner(1882  1974, Germany)and Robert Ochsenfeld(1901  1993, Germany)discovered the total expulsion of the external magnetic fields from superconductors  Meissner effect / Meissner-Ochsenfeld effect. • In 1935, Fritz Wolfgang London(1900  1954, Germany-USA) and Heinz London(1907  1970, Germany) showed that the Meissner effect was a consequence of electromagnetic free energy minimisation of superconducting current  London Theory. • In 1941, Lev Davidovich Landau(1908  1968, USSR) addressed his theory of second-order phase transitions with a Schrodingerlike equation  successful to describe the macroscopic properties of superconductors. • In 1950, and Vitaly Lazarevich Ginzburg(1916  2006, USSR)  the phenomenological Ginzburg-Landau Theory. • In 1957, John Bardeen (1908  1991, USA), Leon Neil Cooper (1930  , USA) and John Robert Schrieffer (1931  ,USA) published the microscopic theory of superconductivity, the concept of Cooper pairs was introduced. • In 1957, Alexei Alexeyevich Abrikosov (1928  , USSR) showed that Ginzburg-Landau theory predicts the division of superconductors into the two categories now referred to as Type I and Type II  the theory of the mixed state of type-II superconductors by analogy with superfluidity in helium and the concept of magnetic vortices / fluxoids was introduced. In 1908, Heike Kammerling-Onnes (18531926, Netherlands) started his career by building liquefiers and was the first to produce liquid helium (TB ~ 4.2K)  used later to investigate the electrical properties of metals at low temperature. In 1911, one of his students, Gilles Holst, observed that the resistance of a mercury wire completely vanished at a temperature slightly below 4.2K. Kammerling-Onnes called it the superconducting state. (Kammerling-Onnes was awared the 1913 Nobel Prize in Physics ‘for his investigations on the properties of matter at low temperatures which led to the production of liquid helium.’) Landau’s theory to explain why liquid helium was super-fluid earned him the 1962 Nobel Prize for Physics. It had been noted experimentally that if liquid helium at these low temperatures was placed in a beaker, then it climbed out of the beaker until the level outside was equal to that inside. Similarly liquid helium would climb into the beaker if the level outside exceeded that in the beaker. Landau devised a theory to explain such behaviour which was published in 1941. It predicted a new phenomenon, namely a temperature wave described a "second sound", and three years later experimental evidence produced in Moscow confirmed the existence of "second sound". In 1972, the microscopic theory of superconductors earned its authors, Bardeen, Cooper and Schrieffer the Nobel Prize in Physics ‘for their jointly developed theory of superconductivity, usually called the BCS-theory’. <Landau> In 2003, Abrikosov and Ginzburg alongside Anthony James Legget (1938  , UK) were awarded Nobel Prize for pioneering contributions to the theory of superconductors and superfluids.  More theoretical developments and to come! <First Temperature vs. Resistance Graph for a High Tc Superconductor> <Heike Kamerlingh Onnes> <The First Measure of Superconductivity> <John Bardeen> <Leon Neil Cooper> <John Robert Schrieffer>