Difference between revisions of "Evanescent waves"
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== Numerical Analysis== | == Numerical Analysis== | ||
| − | @Aero performed calculations for evanescent waves leaking from the EM Drive and producing an external near-field. He used a two-dimensional MEEP Finite Difference model that modeled the EM Drive as a perfectly flat trapezium. Maxwell's equations were solved in the 2-D domain, thus the transverse electromagnetic vector could only be represented as a scalar. The 2-D model was due to the enormous amount of memory and computer time required by the Finite Difference method, which made a 3-D model in a home PC | + | @Aero performed calculations for evanescent waves leaking from the EM Drive and producing an external near-field. He used a two-dimensional MEEP Finite Difference model that modeled the EM Drive as a perfectly flat trapezium. Maxwell's equations were solved in the 2-D domain, thus the transverse electromagnetic vector could only be represented as a scalar. The 2-D model was due to the enormous amount of memory and computer time required by the Finite Difference method, which made a 3-D model in a home PC not practical. The results from the 2-D analysis showed an efficiency rating 2-3 times that of a perfectly collimated photon drive, which is beneath the reported measurements of EM Drive by NASA Eagleworks, Shawyer's SPR and Prof. Juan Yang's team at NWPU.<ref>[http://forum.nasaspaceflight.com/index.php?topic=36313.msg1313876#msg1313876 Initial calculations by aero.]</ref> |
Utilizing [http://ab-initio.mit.edu/wiki/index.php/Meep MEEP] 2-D model, the conclusion was that due to rapid dropoff at the frustum surface, evanescent waves were of insufficient magnitude to explain the observed thrust.<ref>[http://forum.nasaspaceflight.com/index.php?topic=36313.msg1330521#msg1330521 this post by @aero on modeled evanescent waves]</ref>. See details about @aero's [http://forum.nasaspaceflight.com/index.php?topic=37642.msg1382078#msg1382078 MEEP control file]. | Utilizing [http://ab-initio.mit.edu/wiki/index.php/Meep MEEP] 2-D model, the conclusion was that due to rapid dropoff at the frustum surface, evanescent waves were of insufficient magnitude to explain the observed thrust.<ref>[http://forum.nasaspaceflight.com/index.php?topic=36313.msg1330521#msg1330521 this post by @aero on modeled evanescent waves]</ref>. See details about @aero's [http://forum.nasaspaceflight.com/index.php?topic=37642.msg1382078#msg1382078 MEEP control file]. | ||
Revision as of 14:44, 1 June 2015
As first proposed by Aero and later refined by Rodal on the NSF forums, this theory proposes the EmDrive's tapered conical design causes a gradient in the electric field generated by the Rf source. As the EM waves inside the fustrum travel toward the small end, they are attenuated by the constricting geometry, producing evanescent waves that carry momentum. The device must then move to preserve conservation of momentum.[1]
Status
Numerical Analysis
@Aero performed calculations for evanescent waves leaking from the EM Drive and producing an external near-field. He used a two-dimensional MEEP Finite Difference model that modeled the EM Drive as a perfectly flat trapezium. Maxwell's equations were solved in the 2-D domain, thus the transverse electromagnetic vector could only be represented as a scalar. The 2-D model was due to the enormous amount of memory and computer time required by the Finite Difference method, which made a 3-D model in a home PC not practical. The results from the 2-D analysis showed an efficiency rating 2-3 times that of a perfectly collimated photon drive, which is beneath the reported measurements of EM Drive by NASA Eagleworks, Shawyer's SPR and Prof. Juan Yang's team at NWPU.[2]
Utilizing MEEP 2-D model, the conclusion was that due to rapid dropoff at the frustum surface, evanescent waves were of insufficient magnitude to explain the observed thrust.[3]. See details about @aero's MEEP control file.
Relevant Papers
- "Electromagnetic fields and transmission properties in tapered hollow metallic waveguides" by Xiahui Zeng and Dianyuan Fan. Optics Express Vol. 17, Issue 1, pp. 34-45 (2009) •doi: 10.1364/OE.17.0
- "Extraordinary momentum and spin in evanescent waves" by Konstantin Y. Bliokh, Aleksandr Y. Bekshaev, and Franco Nori - See Supplementary Table 1.
- https://en.wikipedia.org/wiki/Mie_scattering
- http://thermopedia.com/content/137/
- http://www.orc.soton.ac.uk/publications/theses/1460T_lnn/1460T_lnn_03.pdf
- "Superluminal propagation of evanescent modes as a quantum effect" by Zhi-Yong Wang, Cai-Dong Xiong, Bing He.
- http://wwwsis.lnf.infn.it/pub/INFN-FM-00-04.pdf - I like Appendix B
- http://arxiv.org/pdf/1211.0530v2.pdf - This one just hints at our situation.
- http://bit.ly/1Ja6QLV - Again, hints
- http://tuttle.merc.iastate.edu/ee439/topics/tunneling.pdf - Tunneling and evanescent wave math are very similar.
- http://en.wikipedia.org/wiki/Maxwell_stress_tensor - Not quite sure why this is here, maybe the stress-energy tensor derivation?
