Magnetic field gradient coil assembly and method of designing same
AssigneeJEOL Ltd.
InventorKenichi Hasegawa
Life of this patent
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Abstract
A method of designing a small-sized, self-shielding magnetic field gradient coil assembly that is for use in an NMR spectrometer, provides high approximation accuracy, is simple in structure, and has a large inside diameter. The gradient coil assembly consists of tightly wound inner and outer coils. The designing process starts with setting or resetting the number of the inner coils and the number of turns of each inner coil. Their positions are optimized such that the magnetic field gradient strength falls within a tolerable range under shielded condition. Then, the number of the outer coils and the number of turns of each outer coil are set. The Fourier components of a current distribution necessary for the outer coils are calculated.
Claims12
A method of designing a magnetic field gradient coil assembly using wound inner and outer coils, said method comprising the steps of:
- setting or resetting the number of said inner coils and optimizing their positions such that a resulting magnetic field strength falls within a tolerable range of a target magnetic field gradient under shielded conditions;
- setting or resetting the number of said outer coils and the number of turns of each outer coil;
- calculating Fourier components of an electric current spatial distribution necessary for the outer coils;
- optimizing positions of the outer coils to approximate the Fourier components of the current distribution;
- calculating magnetic fields leaking from the inner and outer coils, respectively;
- calculating magnetic field distortions caused by eddy currents at the outside of said outer coil produced by the leaking magnetic fields;
- and
- resetting the number of the outer coils and the number of turns of each outer coil such that the magnetic field distortions caused by eddy currents fall within a tolerable range.
A magnetic field gradient coil assembly having wound inner and outer coils, said magnetic field gradient coil assembly having been designed by a method comprising the steps of:
- setting or resetting the number of said inner coils and the number of turns of each inner coil and optimizing their positions such that a resulting magnetic field strength falls within a tolerable range of a target magnetic field gradient under shielded conditions;
- setting the number of said outer coils and the number of turns of each outer coil;
- calculating Fourier components of an electric current spatial distribution necessary for the outer coils;
- optimizing positions of the outer coils to approximate the Fourier components of the current distribution;
- calculating magnetic fields leaking from the inner and outer coils, respectively;
- calculating magnetic field distortion caused by eddy currents at the outside of said outer coil produced by leaking magnetic fields;
- and
- resetting the number of the outer coils and the number of turns of each outer coil such that the magnetic field distortions caused by eddy currents fall within a tolerable range.
Dependencies are inferred from the claim text.