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Design of a model of MagLev train using superconductorSupervisor-Prof. Neeraj Khare Naveeen Khandelwal 2008ph10628
objectiveTo prepare superconductor(YBCO) pellets in Lab.To study the properties of superconductor (YBCO)Design of Maglev Vehicle. Design of magnetic track (Halbach array) for the Maglev.
Superconductor (YBCO) Synthesis Y2O3 + 2 BaCO3 + 3CuO YBa2Cu3O6.5+x + 2CO2 Perovskite structure1. Mixing the chemicals (7 hrs in mortar & pestle)2 Calcination (925-950 0C,18-24 hrs, forms basic crystal structure of YBa2Cu3O6.5) 3 Grinding (6-7 hrs) & Pelletization (1.5 cm diameter) 4 Oxygen annealing (1000 0C ,25-30hrs, sufficient oxygen supply)
Heating cycle (Annealing)
Oxygen is absorbed during cool down. Therefore, it is important to keep the sample in contact with plenty of oxygen during the cool-down.
The absorption is maximum around 550oC so sample is kept for a longer time at this temp.
Cooling rate < 100 oC/hr Heating Rate < 300 oC/hr to avoid thermal stress.
X- ray diffraction
2 d sin () = n For Cu = 1.54060
XRD Various peaks were observed at different angles. Lattice parameters were calculated using these peaks. The calculated a,b,c were similar to the actual lattice parameter. Higher values of a 3.871 instead of 3.821 shows that the sample have mixed phases with varying Tc and oxygen deficient.Lattice const.Calculated Actuala3.871 Ao3.821 Ao
Critical Temp. MeasurementResistance as a function of temp. were measured using four probes.A sharp transition was observed at 91 K.
Frozen image method
In ZFC, the PM produces its diamagnetic mirror image below the HTS top surface, while in FC, two images appear: one is the diamagnetic mirror image and the other is the frozen image
Force Vs height curve
Height (cm) Vertical Levitation force (Nx10) m1 =m2 =1.2 A m2 Cooling Height (h) = 0.5 cm
Magnetic levitation in our sample
Around 4-5mm of levitation was observed in our sample. NdFeB magnets of grade N-35 were used with magnetic strength around 1.2 T.
Design of guide way
Along the length of the track, in the y-direction, there is no variance in the field, which allows the superconductor to move back and fourth with no energy loss. Perpendicular to the length of the track, the bar magnets poles are aligned anti-parallel to each other.This alignment produces a considerably strong gradient in the x-direction
Halbach array Makes optimal use of permanent-magnet material by concentrating the field on the front face of the array, while nearly cancelling the field on the back face of the array.
Vehicle designdesigned to enable keeping of YBCO pellets in considerable amount of liquid Nitrogen. Two big pellets act as main levitators, which lifts the vehicle above the guide way. 4 small pellets act as Auxiliary levitators, which stabilize the lateral swinging of vehicle.vehicle is made out of polyurethane foam with very good thermal properties (thermal insulation).
YBCO pellets (Main levitators)YBCO pellets (Auxiliary levitators)
Work done Qualitative and Quantitative Analysis of levitation force and Stiffness using frozen image method.Preparation of YBCO sample using solid state method.XRD and Critical temperature measurement of YBCO sampleSchematic design of track and vehicle.
ConclusionXRD of YBCO sample shows that Oxygen content has significant role in determining the superconducting behavior of YBCO Due to oxygen deficiency in the sample, it contain mixed phases with varying Tc .Levitation force was very weak in comparison to the theoretical prediction.levitation force was not enough to suspend the maglev model's weight, so we were not able to implement the design.
John R. Hull and Ahmet Cansiz "Vertical and lateral forces between a permanent magnet and a high temperature superconductor" JOURNAL OF APPLIED PHYSICS VOLUME 86, NUMBER 11http://www.futurescience.com/scpart1.htmlP. Strehlow and M. C. Sullivan Levitation and Suspension of a Superconductor over a Magnetic Track Charles American Journal of Physics -- September 2009 -- Volume 77, Issue 9ermk, R.; Barto, L.; Spal, P.; Bartk, J. & Vavk, J. Overview of magnetic levitation principles and their application in Maglev trains Advance engineering 2(2008) ISSN 1846-5900