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Transformation Optics for Controlling DC Magnetic Field
KTH, School of Electrical Engineering (EES), Electromagnetic Engineering. KTH, School of Information and Communication Technology (ICT), Centres, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Based on the form-invariant of Maxwell’s equations under coordinate transformations, we extend the theoryof transformation optics to transformation magneto-statics, which can design magnets through coordinatetransformations. Some novel DC magnetic field illusions created by magnets (e.g. rescaling magnets,cancelling magnets and overlapping magnets) are designed and verified by numerical simulations. Ourresearch will open a new door to designing magnets and controlling DC magnetic fields.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2014. Vol. 4, xiv, 81 p.6593- p.
Series
TRITA-EE, ISSN 1653-5146 ; 2014:051
Keyword [en]
Transformation magneto-statics, magnets, DC magnetic field
National Category
Materials Engineering Electrical Engineering, Electronic Engineering, Information Engineering Other Physics Topics
Research subject
Electrical Engineering; Materials Science and Engineering
Identifiers
URN: urn:nbn:se:kth:diva-155326ISBN: 978-91-7595-328-1 (print)OAI: oai:DiVA.org:kth-155326DiVA: diva2:760865
Public defence
2014-12-01, F3, Lindstedtsvägen 26, KTH, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

QC 20141105

Available from: 2014-11-05 Created: 2014-11-04 Last updated: 2014-11-05Bibliographically approved
List of papers
1. Create a uniform static magnetic field over 50 t in a large free space region
Open this publication in new window or tab >>Create a uniform static magnetic field over 50 t in a large free space region
2013 (English)In: Progress In Electromagnetics Research, ISSN 1070-4698, E-ISSN 1559-8985, Vol. 137, 149-157 p.Article in journal (Refereed) Published
Abstract [en]

We propose a compact passive device as a super-concentrator to create an extremely high uniform static magnetic field over 50 T in a large two-dimensional free space from a weak background magnetic field. Such an amazing thing becomes possible for the first time, thanks to space-folded transformation and metamaterials for static magnetic fields. Finite element method (FEM) is utilized to verify the performance of the proposed device.

Keyword
Transformation Optics, Cloak, Metamaterials, Stimulation, Sensors
National Category
Engineering and Technology
Identifiers
urn:nbn:se:kth:diva-122537 (URN)10.2528/PIER13012802 (DOI)000316931700010 ()2-s2.0-84874363558 (Scopus ID)
Funder
Swedish Research Council, 621-2011-4620
Note

QC 20130527

Available from: 2013-05-27 Created: 2013-05-23 Last updated: 2017-12-06Bibliographically approved
2. Static magnetic field concentration and enhancement using magnetic materials with positive permeability
Open this publication in new window or tab >>Static magnetic field concentration and enhancement using magnetic materials with positive permeability
2013 (English)In: Progress In Electromagnetics Research, ISSN 1070-4698, E-ISSN 1559-8985, Vol. 142, 579-590 p.Article in journal (Refereed) Published
Abstract [en]

In this paper a novel compressor for static magnetic fields is proposed based on finite embedded transformation optics. When the DC magnetic field passes through the designed device, the magnetic field can be compressed inside the device. After it passes through the device, one can obtain an enhanced static magnetic field behind the output surface of the device (in a free space region). We can also combine our compressor with some other structures to get a higher static magnetic field enhancement in a free space region. In contrast with other devices based on transformation optics for enhancing static magnetic fields, our device is not a closed structure and thus has some special applications (e.g., for controlling magnetic nano-particles for gene and drug delivery). The designed compressor can be constructed by using currently available materials or DC meta-materials with positive permeability. Numerical simulation verifies good performance of our device.

Keyword
Closed structures, DC magnetic field, Free spaces, Magnetic nano-particles, Special applications, Static magnetic fields, Transformation optics
National Category
Engineering and Technology
Identifiers
urn:nbn:se:kth:diva-133246 (URN)10.2528/PIER13082102 (DOI)000327478000034 ()2-s2.0-84884574406 (Scopus ID)
Funder
Swedish Research Council, 621-2011-4620
Note

QC 20131030

Available from: 2013-10-30 Created: 2013-10-29 Last updated: 2017-12-06Bibliographically approved
3. DC magnetic concentrator and omnidirectional cascaded cloak by using only one or two homogeneous anisotropic materials of positive permeability
Open this publication in new window or tab >>DC magnetic concentrator and omnidirectional cascaded cloak by using only one or two homogeneous anisotropic materials of positive permeability
2013 (English)In: Progress In Electromagnetics Research, ISSN 1070-4698, E-ISSN 1559-8985, Vol. 142, 683-699 p.Article in journal (Refereed) Published
Abstract [en]

A novel concentrator for static magnetic field enhancement is proposed and designed utilizing transformation optics. Compared with other devices for static magnetic field enhancement, our device has many good features: first, our concentrator can achieve a DC magnetic field enhancement in a relatively large free space with high uniformity. Secondly, our concentrator is composed by only one or two homogenous anisotropic materials with principal value greater than zero (without any infinitely large or zero value), which can be achieved by using currently available materials. Thirdly, the geometrical shape of the proposed device determines the enhancement factor and the permeability of the device. After choosing suitable geometrical parameters, we can obtain a concentration with a suitable enhancement factor and a material requirement that is easily achievable. The proposed concentrator will have many important applications in many areas (e.g., magnetic resonance imaging and magnetic sensors). Based on the same theoretical model, we also proposed a cascaded shielding device cloak for static magnetic fields. The proposed DC magnetic shielding device can be realized without using any material of zero permeability, and will have potential applications in, e.g., hiding a metallic object from being detected by a metal locator.

Keyword
Anisotropic material, Enhancement factor, Geometrical shapes, Magnetic concentrator, Material requirements, Static magnetic fields, Theoretical modeling, Transformation optics
National Category
Electrical Engineering, Electronic Engineering, Information Engineering Telecommunications
Identifiers
urn:nbn:se:kth:diva-139194 (URN)10.2528/PIER13092509 (DOI)000327478000040 ()2-s2.0-84885908717 (Scopus ID)
Funder
Swedish Research Council, 621-2011-4620
Note

QC 20140110

Available from: 2014-01-10 Created: 2014-01-08 Last updated: 2017-12-06Bibliographically approved
4. Transformation magneto-statics and illusions for magnets
Open this publication in new window or tab >>Transformation magneto-statics and illusions for magnets
2014 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 4, 6593- p.Article in journal (Refereed) Published
Abstract [en]

Based on the form-invariant of Maxwell’s equations under coordinate transformations, we extend the theoryof transformation optics to transformation magneto-statics, which can design magnets through coordinatetransformations. Some novel DC magnetic field illusions created by magnets (e.g. rescaling magnets,cancelling magnets and overlapping magnets) are designed and verified by numerical simulations. Ourresearch will open a new door to designing magnets and controlling DC magnetic fields.

Keyword
Transformation magneto-statics, magnets, DC magnetic field
National Category
Materials Engineering Electrical Engineering, Electronic Engineering, Information Engineering Other Physics Topics
Research subject
Electrical Engineering; Materials Science and Engineering
Identifiers
urn:nbn:se:kth:diva-154888 (URN)10.1038/srep06593 (DOI)000343084500001 ()25307319 (PubMedID)
Funder
Swedish Research Council, 621-2011-4620
Note

QC 20141029

Available from: 2014-10-28 Created: 2014-10-28 Last updated: 2017-12-05Bibliographically approved
5. Transformation inside a Null-Space Region and a DC Magnetic Funnel for Achieving an Enhanced Magnetic Flux with a Large Gradient
Open this publication in new window or tab >>Transformation inside a Null-Space Region and a DC Magnetic Funnel for Achieving an Enhanced Magnetic Flux with a Large Gradient
2014 (English)In: Progress In Electromagnetics Research, ISSN 1070-4698, E-ISSN 1559-8985, Vol. 146, 143-153 p.Article in journal (Refereed) Published
Abstract [en]

The idea of transformation inside a null-space region is introduced for the first time, and used to design a novel DC magnetic compressor that concentrates DC magnetic flux greatly and behaves as a DC magnetic funnel. The proposed device can be used as a passive DC magnetic lens to achieve an enhanced DC magnetic field (e.g., 7.9 times or more depending on the size and other parameters of the compressor) with a large gradient (e.g., 450 T/m or more) in free space. After some theoretical approximation, the proposed device can be easily constructed by using a combination of superconductors and ferromagnetic materials. Numerical simulations are given to verify the performance of our device. The proposed method (use a null-space region as the reference space) can be extended to reduce the material requirement when designing other devices with transformation optics.

Keyword
Positive Permeability, Field, Realization, Water, Cloak
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-149238 (URN)10.2528/PIER14031707 (DOI)000339161500015 ()
Funder
Swedish Research Council
Note

QC 20140819

Available from: 2014-08-19 Created: 2014-08-18 Last updated: 2017-12-05Bibliographically approved
6. Experimental Realization of Strong DC Magnetic Enhancement with Transformation Optics
Open this publication in new window or tab >>Experimental Realization of Strong DC Magnetic Enhancement with Transformation Optics
2014 (English)In: Progress In Electromagnetics Research, ISSN 1070-4698, E-ISSN 1559-8985, Vol. 146, 187-194 p.Article in journal (Refereed) Published
Abstract [en]

A passive DC magnetic concentrator is designed with transformation optics (TO) and realized by meta-materials. The passive DC magnetic concentrator based on space compression transformation can greatly enhance the magnetic field in a free space region and can be used for e.g., improving the sensitivity of magnetic sensors and increasing the efficiency of wireless energy transmission. The magnetic property of the medium obtained by TO is extremely anisotropic. To solve this, we use magnetic metamaterials made of alternated high-permeability ferromagnetic (HPF) materials and high-temperature superconductor (HTS) materials. We optimize our structure by conducting simulations using the finite element method (FEM) and experimentally demonstrate a strong, 4.74-time enhancement of the DC magnetic field by our meta-material magnetic concentrator. We also demonstrate that a simplified structure with only HPF materials working at room temperature can still gives 3.84-time enhancement of the DC magnetic field. The experimental results are in good agreement with the numerical simulations based on FEM.

Keyword
Positive Permeability, Cloak, Field
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-149239 (URN)10.2528/PIER14042704 (DOI)000339161500019 ()
Funder
Swedish Research Council
Note

QC 20140819

Available from: 2014-08-19 Created: 2014-08-18 Last updated: 2017-12-05Bibliographically approved

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