Faraday shields within a solenoidal coil to reduce sample heating: numerical comparison of designs and experimental verification.
A comparison of methods to decrease RF power dissipation and related heating in conductive samples using passive conductors surrounding a sample in a solenoid coil is presented. Full-Maxwell finite difference time domain numerical calculations were performed to evaluate the effect of the passive conductors by calculating conservative and magnetically-induced electric field and magnetic field distributions. To validate the simulation method, experimental measurements of temperature increase were conducted using a solenoidal coil (diameter 3 mm), a saline sample (10 mM NaCl) and passive copper shielding wires (50 microm diameter). The temperature increase was 58% lower with the copper wires present for several different input powers to the coil. This was in good agreement with simulation for the same geometry, which indicated 57% lower power dissipated in the sample with conductors present. Simulations indicate that some designs should be capable of reducing temperature increase by more than 85%.
Park
BuSik
B
Department of Bioengineering, The Pennsylvania State University, College of Medicine, Hershey, PA 17033, USA.
Neuberger
Thomas
T
Webb
Andrew G
AG
Bigler
Don C
DC
Collins
Christopher M
CM
D003198:Computer Simulation; D004867:Equipment Design; D019544:Equipment Failure Analysis; D008279:Magnetic Resonance Imaging / Q000295:instrumentation*; D009682:Magnetic Resonance Spectroscopy / Q000295:instrumentation*; D008280:Magnetics / Q000295:instrumentation*; D008962:Models, Theoretical; D011829:Radiation Dosage; D011835:Radiation Protection / Q000295:instrumentation*; D012542:Scattering, Radiation; D013696:Temperature