Over the past seven years, a microwave engineer named Roger Shawyer has built a number of “EM drives”, short for Electromagnetic Drive, which consists of a cavity built to contain resonating microwaves. Shawyer claims the cavity produces a directional force and has video evidence to support his claim, however, the device has not been properly duplicated in a laboratory setting. An experiment is currently underway at the University of Alberta which requires funding to eliminate all mundane explanations for the movement of Shawyer’s cavity including buoyancy, “ion wind” and any type of reaction propulsion. In collaboration with Dr. Karumudi, assistant professor of microwave engineering at the University of Alberta, funds are required to purchase simulation tools and pay for the use of the university’s lab facilities. If the cavity moves and all mundane explanations can be eliminated, then this could indicate a significant breakthrough in propulsion. The initial application will include orbital station-keeping of satellites, however, if the force can be scaled up significantly, and Shawyer’s recent experimental claims suggest it can, then a much larger force could be possible. A duplicate cavity has been designed and most of the necessary parts purchased, but modest supplemental funding is required for final fabrication and testing.
After a thirty-year career in microwave engineering, a British engineer named Roger Shawyer decided to investigate an anomaly that had plagued superconducting linear accelerators. Linear accelerators use high power resonating chambers to increase the speed of the particles as they pass through and in doing so, ran into a problem with the cavities detuning . At full power, the cavities were decreasing their lengths slightly. In 2001 after retiring from his job at EADS Astrium, he created a company with external funding to see if the force that was causing the detuning could be used for propulsion.
Over the course of the past seven years, Roger Shawyer has built three generations of the microwave thrusters, each with a higher Q or Quality factor, a measure of the resonance efficiency. The first tapered cavity, made out of copper, had a Q of 5900 and for approximately 500W input power, produced 84mN of force. The second copper cavity, shown below, he called the “Demonstration Engine” (see Figure 1), had a Q of 50,000 and produced 214mN of force.
Shawyer has recently created a superconducting version of his cavity which has a Q of 6,800,000 and although he got “exactly the results” he expected, he has not released the force measurements.
Shawyer’s results are controversial because the theory Shawyer suggests to explain the asymmetrical force has significant deficiencies. However, the theory is outside of the scope of this proposal whose sole purpose is to independently reproduce the results and eliminate all mundane explanations. All the steps Shawyer took to create the cavity are being duplicated and require no input from Shawyer. The steps include simulating the cavity to ensure a proper resonant frequency and Quality factor, fabricating the cavity from raw sheets of copper and using a commercial grade magnetron to power the cavity. The duplication will reproduce the significant attributes of Shawyer’s cavity including the shape, frequency and power.
This independent verification is not unique. As mentioned in a September 24th, 2008 article in Wired Magazine a Chinese professor by the name of Yang Jan at the Northwestern Polytechnical University (NPU) in Xi’an is also attempting to recreate the effect and should have results within a year.
The experiment will reproduce the “Demonstration Engine” (shown in Figure one above) and a simplified 3D model is shown below (figure two):
Because the cavity is enclosed and little energy will be lost within it, a circulator is required to take the significant amount of reflected power and dissipate it within a load. The load will be water cooled by a passive external radiator.
Using the lab facilities at the University of Alberta, the experimental apparatus will be constructed. Once complete and tuned, if the cavity moves, the following experiments will be conducted to ensure that all mundane explanations are eliminated:
With the exception of buoyancy, all other types of propulsion are reaction-based. A rocket launches or a jet aircraft flies because high velocity hot air gases are pushed out the back. Wheeled vehicles accelerate because the wheels push on a surface and a helicopter or aircraft pulls it self through the air by pushing air backwards with its propeller. All of these methods rely on Newton’s third law, that for every action, there is an opposite and equal reaction.
Because most existing propulsion is reaction based, this is the mostly likely explanation for the thrust generated by Shawyer’s cavity and must be experimentally addressed first. The best-known method is to hang the device from a pendulum, where it cannot push on anything except the surrounding air. The cavity will also be put inside a sealed envelope and hung from a pendulum, which will eliminate reaction mass as a possible thrust mechanism.
Inside a Faraday Cage
Another possible explanation is that there is some type of electrical or magnetic interaction occurring between the cavity and its surroundings. By enclosing the cavity inside a large grounded copper cage, also known as a Faraday cage, electromagnetic interactions with the surroundings can be eliminated.
Possible types of interaction are the repulsion and attraction generated by magnetism. It might be possible that the cavity is somehow being magnetized which is causing it to be attracted to, or repelled from something in its surroundings. The attraction caused by static electricity is also another interaction the Faraday cage will help to eliminate.
When the gases in an enclosed container are lighter than its surroundings, it will create buoyancy. Because the cavity will likely heat and air can escape, it is possible that the density of air inside could be less then the density outside, leading to buoyancy.
Buoyancy can be eliminated by carefully measuring the temperature of the cavity at various points to see if it is heating. Because the weight of the cavity and cooling apparatus is quite heavy, it would take a considerable amount of hot air in order to create thrust. Calculations show that it would take a considerable volume of heated air to move the device in any meaningful way. Lighter air would also tend to collect at the large end of the cavity but Shawyer’s video shows that it moves toward the narrow end which is in the opposite direction expected if buoyancy was the cause.
There is a well-known effect called the Biefeld-Brown effect or “Ion Wind” which is caused by charged metal surfaces ionizing the surrounding air by corona discharge. The ions are then attracted toward the oppositely-polarized conductor. If the voltage differences are significant enough, the moving ions can impart a significant force as is evident by the “lifters” which are of frequent interest in the hobbyist community.
The first step to eliminating the Ion wind effect is to make sure there are no voltage differences between any of the parts on the apparatus that could lead to the effect. The second test is simpler because “Lifters” can lift about a gram per watt generating considerable movement of air past the conductors. The movement of air should be detectable with a simple smoke displacement test.
The final and best test to eliminate the Ion Wind effect, is to enclose the device in a evacuated sealed container which will remove any air without which the ions will not be able to generate thrust.
The initial application is for satellite orbital station-keeping and orientation. A cavity that can produce a unidirectional force with only microwaves has an advantage in terms of launch weight and longevity over a propellant-based propulsion method. Shawyer reported that his first test cavity produced 85 mN of thrust compared to 92mN for the NSTAR ion drive, but Shawyer’s cavity only consumes a quarter of the power. The microwave drive system including the cavity also weighs less than 7 kilos, compared to over 30 kilos for the ion drive. The biggest difference is in propellant because the NSTAR uses 10 grams per hour whereas the microwave cavity uses none.
If the force can be scaled up, then it might be possible to eventually replace most forms of reaction-based propulsion. It is the possibility of replacing reaction-based propulsion that drives the long-term interest in this type of research.
Conclusion and Benefits
Any new propulsion mechanism can be of significant benefit to humankind, especially in an era when the dominant fuel-based propulsion has considerable negative side effects, from climate change to funding terrorists. Besides energy, the transportation sector is a significant driver of human wealth and any improvement, no matter how modest, has large secondary effects. However, any new propulsion mechanism needs to be thoroughly tested under properly-controlled laboratory conditions, to eliminate all possible mundane explanations. This proposal may open the door to a significantly better future.
The results of the proposed experiment will be properly documented, and used to produce an academic paper on the subject of Shawyer’s experimental claims, which will be submitted for peer review to the appropriate physics journals.
- Roger Shawyer and the EM Drive
- Lorentz-Force Detuning
- Computer Simulation Technology – Microwave Studio
- Describes an ION thruster including thrust measurements
- Demonstrator Engine, video footage of movement, Roger Shawyer
- “Lorentz Force Detuning Analysis of the Spallation Neutron Source Accelerating Cavities”, R. Mitchel, et.all, Los Almos National Lab
- “Lorentz Force Detuning Compensation System for Accelerating Field Gradients Up to 35MV/M for Superconducting XFEL and TESLA Nine-Cell Cavities”, P. Sekalski, et.al., Technical University of Lodz, DMSC, Poldan, CARE conference, 2001.
- Background of EMdrive, EMDrive.com, Roger Shawyer
- “Electrical Propulsion Unit for Spacecraft”, UK Patent, GB 2 229 865 A, 03.10.1990
- “Microwave Thruster for Spacecraft”, UK Patent, GB 2 334 761 A, 01.09.1999
- “Thrust Producing Device Using Microwaves”, UK Patent, GB 2 399 601 A, 22.09.2004
- Demonstrator Engine, video footage of movement, Roger Shawyer
- “John Whitmore: What next? Flying Saucers?”, John Whitmore, UK Telegraph News, August 2008
- “Chinese Say They’re Building ‘Impossible’ Space Drive“, David Hambling, September 24th, 2008
- Hot Air Balloons on How Stuff Works
- The Biefeld-Brown Effect
- Lifters or Ionocraft