Acknowledgements Thermal Simulation Future Work Design Introduction MAGNETIC LEVITATION FOR SPHERICAL DRAG-FREE SENSOR TESTING Abdul Alfauwaz * , Abdulaziz Alhusain, John Lipa and Dan Debra CENTER OF EXCELLENCE in Aeronautics and Astronautics (CEAA) Stanford University * [email protected] • The system will be used to test the three-axis optical sensor system, DOSS, that is being developed separately, by rapidly switching to the DOSS sensor while the ball is levitated. • Small magnetic pulses will be used to simulate thruster perturbations in the plane orthogonal to the support axis This research is supported by CENTER OF EXCELLENCE in Aeronautics and Astronautics and Stanford University. We thank COMSOL technical support for their useful feedback. . • Design and build a system that can levitate and hold a hollow sphere in vacuum, “simulating zero -g operation” • Spin the TM by using 4 coils to produce a rotating magnetic field around the equator of the sphere. System features: • Coil designed to run in vacuum for at least 2 hours without any damage. •The ball position sensor is optical and is made up of an infrared emitter and a pair of phototransistors. • The system is designed to restore the ball to the levitated position if it drops out of lock, as it might be needed while it is running in vacuum. Magnetic analysis: • Used COMSOL to analyze the coil and simulate the magnetic field which is produce by coil. • Calculate the magnetic force on the sphere for different situation • The figure below shows the electromagnetic force versus the distance between the coil and the sphere for different currents. Magnetic sphere Levitation coil IR source Photodiode Experiment Levitation Experiment Spinning 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 0 0.2 0.4 0.6 0.8 1 Distance from the Coil (mm) Electromagnetic Force (N) Electromagnetic force VS. Distance Coil I=0.10 A. Coil I=0.12 A. Coil I=0.14 A. Coil I=0.16 A. Coil I=0.18 A. Coil I=0.20 A. Sphere Gravity Force Magnetic force Gravity force Spinning coils Coil Power Dissipation • Used COMSOL to simulate thermal simulation in air and vacuum. • Install 2 temperature sensor in the coil • Run the coil in vacuum for about 3 hours. .F=qv X B Coil In vacuum with current 0.26A ~2 hours Multislice: Magnetic flux density norm (T) Arrow Volume: Magnetic field Vacuum top lid Lens between sphere and detector Detector Lens between sphere and laser source Laser source Experiment running in air before it is moved to vacuum. Was able to spin the sphere up to 11Hz in vacuum. 4 coils Sphere is spinning in vacuum