US4724412A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of determining coil arrangement of an actively shielded magnetic resonance magnet
Assignee: General Electric Co
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Filing: 1987-08-03
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Granted: 1988-02-09
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Expires: 2007-08-03
Abstract
Abstract A method of making an actively shielded magnet is provided which uses a Monte Carlo simulation to minimize the amount of total conductor material used in a coil arrangement. This method reduces stray field while providing superior magnetic field homogeneity in the working volume of the magnet. Each coil contributes to the overall homogeneity of the magnet.
Inventors
- 👤 Ahmed K. Kalafala
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 06:43
CPC Classifications
G; G01; G01R; G01R33/00; G01R33/20; G01R33/28; G01R33/38; G01R33/387; G01R33/3875; G01R33/42; G01R33/421; G01R33/4215
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
153 words
A method of determining a coil arrangement in an actively shielded magnet comprising the steps of: (a) selecting an axial and radial range for a predetermined number of coil pairs; (b) selecting a desired field strength in the interior of the coils; (c) randomly selecting coaxial coil positions for each of the coil pairs within the selected axial and radial ranges, the coil pairs symmetrically positioned in the axial direction; (d) determining the currents in each of the coils required to achieve the desired field strength and achieve selected harmonic elimination inside and outside the coils, the number of harmonics eliminated being related to the number of coil pairs; (e) summing the amount of conductor needed in each coil to carry the current in that coil; (f) minimizing the conductor required by repeating steps c-f a predetermined number of times and saving the coil configuration which requires the least amount of conductor material.
Claim 2
Independent Claim
153 words
A method of determining a coil arrangement in an actively shielded magnet comprising the steps of: (a) selecting an axial and radial range for a predetermined number of coil pairs; (b) selecting a desired field strength in the interior of the coils; (c) randomly selecting coaxial coil positions for each of the coil pairs within the selected axial and radial ranges, the coil pairs symmetrically positioned in the axial direction; (d) determining the currents in each of the coils required to achieve the desired field strength and achieve selected harmonic elimination inside and outside the coils, the number of harmonics eliminated being related to the number of coil pairs; (e) summing the amount of conductor needed in each coil to carry the current in that coil; (f) minimizing the conductor required by repeating steps c-f a predetermined number of times and saving the coil configuration which requires the least amount of conductor material.
Claim 3
Dependent Claim
17 words
The method of claim 1 wherein the radial range is restricted to a plurality of discrete radii.
Claim 4
Dependent Claim
17 words
The method of claim 1 wherein the axial range is restricted to a plurality of axial planes.
Claim 5
Dependent Claim
41 words
The method of claim 1 wherein said step of minimizing further comprises reducing the permissible axial range for each coil based on the arrangement found to require the minimum conductor material and again repeating steps c-f a predetermined number of times.
Claim 6
Independent Claim
170 words
A method of making an actively shielded magnet comprising the steps of: (a) selecting an axial and radial range for a predetermined number of coil pairs; (b) selecting a desired field strength in the interior of the coils; (c) randomly selecting coaxial coil positions for each of the coil pairs within the selected axial and radial ranges the coil pairs symmetrically positioned in the axial direction; (d) determining the currents in each of the coils required to achieve the desired field strength and achieve selected harmonic elimination inside and outside the coils, the number of harmonics eliminated being related to the number of coil pairs; (e) summing the amount of conductor needed in each coil to carry the current in that coil; (f) minimizing the amount of conductor required by repeating steps c-f a predetermined number of times and saving the coil configuration which requires the least amount of conductor material; and (g) using the coil arrangement requiring the least amount of conductor material to fabricate an actively shielded magnet.
Claim 7
Independent Claim
170 words
A method of making an actively shielded magnet comprising the steps of: (a) selecting an axial and radial range for a predetermined number of coil pairs; (b) selecting a desired field strength in the interior of the coils; (c) randomly selecting coaxial coil positions for each of the coil pairs within the selected axial and radial ranges the coil pairs symmetrically positioned in the axial direction; (d) determining the currents in each of the coils required to achieve the desired field strength and achieve selected harmonic elimination inside and outside the coils, the number of harmonics eliminated being related to the number of coil pairs; (e) summing the amount of conductor needed in each coil to carry the current in that coil; (f) minimizing the amount of conductor required by repeating steps c-f a predetermined number of times and saving the coil configuration which requires the least amount of conductor material; and (g) using the coil arrangement requiring the least amount of conductor material to fabricate an actively shielded magnet.
Claim 8
Dependent Claim
17 words
The method of claim 5 wherein the radial range is restricted to a plurality of discrete radii.
Claim 9
Dependent Claim
41 words
The method of claim 6 wherein said step of minimizing further comprises reducing the permissible axial range for each coil based on the arrangement found to require the minimum conductor material and again repeating steps c-f a predetermined number of times.
Claim 10
Dependent Claim
11 words
An actively shielded magnet made with the process of claim 5.
References Cited (Backward Citations)
US4581580A
Cited
US4523166A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-02-08 | 1991-08-10 | 1992-02-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-02-08 | 1995-08-10 | 1996-02-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-02-08 | 1999-08-10 | 2000-02-09 | $7700.00 | Window Closed / Lapsed |