Presentation on theme: "Flux Jumps in Magnetization of HTS Tubes. Nasser S. Alzayed Physics Dept., King Saud University Riyadh 11451, Saudi Arabia"— Presentation transcript:
Flux Jumps in Magnetization of HTS Tubes. Nasser S. Alzayed Physics Dept., King Saud University Riyadh 11451, Saudi Arabia
Magnetic Shields Superconductors are Expected to Shield the applied Magnetic Fields This Phenomenon is called Missner Effect. The phenomenon take place because the Superconductor creates a screening current that creates an opposite and equal mag. Field
Vortices When The applied mag. Field is large enough, > H C1, magnetic Fluxions (vortices) will spread all over the material However Material is still superconducting (Type II Only)
Large Fields When H ext is larger than H C2, superconductivity will be destroyed altogether.
So …!!! As long as the H ext is < H C1, no Flux penetration should occur. No Flux Creep is expected. Flux Avalanche is not possible.
Flux Creep Model H/H C Thickness
Bean Model Bean Model has been Used since the 60’s to explain for the phenomenon. This model assumes the fulfillment of the local adiabatic conditions for the sample.
Bean Model Simulation Thickness J/J C
Blue Region is Superconducting Strip Magnetic Field is Perpendicular to Strip All Values are normalized Pining Energy used is: H(X) Top M(H) Bottom J(x) middle
When Jumps Happen? We noticed that Jumps took place at very small values. Much Less than H C In this case adiabatic conditions have nothing to do with Flux avalanche
Creep Is impossible Our Flux is detected inside the Tube. Hence it is not due to Flux Creep.
Conclusion These Flux Jumps happen at small values Hence They cannot be attributed to Flux Creep They cannot be due to Flux avalanche We think this is a quantum phenomenon