Explanations on micronewton electromagnetic thruster

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References:
Micronewton electromagnetic thruster
http://scitation.aip.org/content/aip/journal/apl/101/3/10.1063/1.4737940
Applied Physics Letters

Loss of linear momentum in an electrodynamics system: from an analytical approach to simulations
http://onlinewww.jpier.org/PIERM/pier.php?paper=10041307
Progress In Electromagnetics Research M

Contents
Introduction
1. Momentum conservation
2. Numerical calculations
3. Instrumentation

Introduction
Hi my name is Dimitri Charrier and I am the author of the paper "Micronewton Electromagnetic Thruster" published in Applied Physics Letters in 2012. I received many emails from US and Europe related to this work. Questions were about momentum conservation, numerical calculations, and the instrumentation. I will try to cover these three parts. The question raised in this work was how to create a force on an inertial object in vacuum condition? Magnetohydrodynamics, Biefeld-Brown effect, Meissner effect, classical magnets, levitating coils were not fruitful for answering this question. The experiment of a jumping ring from a coil having a transient current was chosen. A model for predicting the force was built based on retarded potentials and Lorentz law. This work was published in 2010 when I was in post-doc in Poitiers. The same year, I had the opportunity to have some equipment for measuring displacements at micrometer scales. I published these results in 2012.

1. Momentum conservation
A lot of papers exist to deal about that loss of momentum (in our case due to conversion of electromagnetic wave to mechanical momentum). Jefimenko published articles and books during his all life in this topic. One particular book is untitled "Causality, Electromagnetic Induction and Gravitation: A Different Approach to the Theory of Electromagnetic and Gravitational Fields". The fourth chapter is called "Action and Reaction in electric magnetic and gravitational fields" is very interesting. The loss of linear momentum is commonly considered in gravitational interactions due to retarded interaction of gravity. In the device, the coil emits electromagnetic wave momentum from its both sides. However one side is with the disc and then the EM waves will transfer its momentum to the disc into mechanical momentum. Clearly, a mechanical momentum is produced on the disc and not the other side of the coil. Therefore, we broke the symmetry. The symmetry breaking is the key in a lot of physical phenomenon.

2. Numerical calculations
I used Mathematica for doing calculations and I used the equation published in the paper to get numerical results.

3. Instrumentation
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