NMR Mandhala Set by QuantumEnthusiast

Last crawled date: 3 years, 1 month ago

This is a Halbach NMR Mandhala (along with several attachments) to be used in small magnetic resonance imaging experiments.
The purpose of the Halbach NMR Mandhala [Magnet Arrangements for Novel Discrete Halbach Layout, created by Raich and Blümler, “Design and Construction of a Dipolar Halbach Array with a Homogeneous Field from Identical Bar Magnets: NMR Mandhalas”, Concepts in Magnetic Resonance part B (Magnetic Resonance Engineering), Vol. 23B(1) 16-25 (2004), DOI 10.1002/cmr.b.20018] is to provide a large, homogeneous magnetic field over a large and accessible volume made from identical and affordable permanent magnets. This improved design uses longer magnets to provide stronger magnetic fields and more homogeneity along the central axis, aiming for samples that will roughly 1 cubic-centimeter in size. The permanent magnets used are still easily purchasable online.
This Thing has two distinct pieces which are designed to work together:
Outer Mandhala
4cm inner diameter; 8cm inner diameter
Eight 1/2" x 1/2"x 2" slots for N52 magnets (K&J Magnetics: https://www.kjmagnetics.com/proddetail.asp?prod=BY088-N52)
Tracks and bar for Inner Mandhala (see below)
Holes in each slot to easily remove the magnets
Inner Mandhala
1.8cm inner diameter; ~4cm outer diameter
Eight 1/4” x 1/4” x 1” slots for N52 magnets (K&J Magnetics: https://www.kjmagnetics.com/proddetail.asp?prod=BX044-N52&cat=168)
Rails on sides fit into rails on Outer Mandhala; the Inner Mandhala sits on the bar in the Outer Mandhala so the middle of the Inner’s magnets are aligned with the centers of the Outer's magnets
The Inner Mandhala slots into the Outer Mandhala for a stronger field (Up to ~.45 T)
The magnets in both the Outer and Inner Mandhala should be oriented according to Raich and Blümer's article (see photo) to get a homogeneous magnetic field.
The attached photos are the Inner and Outer Mandhalas (and then those combined) paired with the field map of it that we found.
Inserting the magnets into the Outer and Inner Mandhalas and inserting the Inner into the Outer Mandhala can be difficult, as the magnets resist these orientations. For us, it has consistently been a two-person job.
These Mandhalas are an improvement on a previous design: (https://www.thingiverse.com/thing:2474075).
This model was constructed by Nick Torres and Ken Zhu based on a design by Jeremiah O'Mahony. Guidance and good-natured mockery from Merideth Frey, PhD. All this happened in beautiful Yonkers, New York.
UPDATE: Changed the bar at the bottom of the Outer Mandhala so removing the Inner Mandhala is easier.