Topologically optimized magnetic lens for magnetic resonance applications

Abstract

Abstract. Improvements to the signal-to-noise ratio of magnetic resonance detection lead to a strong reduction in measurement time, yet as a sole optimization goal for resonator design, it would be an oversimplification of the problem at hand. Multiple constraints, for example for field homogeneity and sample shape, suggest the use of numerical optimization to obtain resonator designs that deliver the intended improvement. Here we consider the 2D Lenz lens to be a sufficiently broadband flux transforming interposer between the sample and a radiofrequency (RF) circuit and to be a flexible and easily manufacturable device family with which to mediate different design requirements. We report on a method to apply topology optimization to determine the optimal layout of a Lenz lens and demonstrate realizations for both low- (45 MHz) and high-frequency (500 MHz) nuclear magnetic resonance.

Lenz Lenses in a Cryoprobe: Boosting NMR Sensitivity Toward Environmental Monitoring of Mass-Limited Samples

“…Lenz lenses are broadband passive magnetic field lenses, which have been shown to improve the signal in a range of applications, from high-pressure NMR to brain tissue imaging. − Rather than replacing the detection coil, Lenz lenses allow the B 1 field from a larger coil to be refocused onto a much smaller sample volume. In turn, the stronger B 1 field at the sample provides strong coupling to the main coil, and the signal detected by the standard coil, in this case the probe cryocoils, is increased.…”