Spaceflight forum is on its eight thread discussing the controversial Emdrive
The objective of the Nasa Spaceflight forum is to analyze whether the EM Drive (a cavity resonating at microwave frequencies) reported "thrust force" is an experimental artifact or whether it is a real propulsion effect that can be used for space applications, and if so, in discussing those possible space propulsion applications. >
There have been several papers trying to determine if the EMdrive operates in a vacuum and speculated on how it might produce propulsion or to explain the anomalies. This AIP Advances paper [On the exhaust of electromagnetic drive] has Nextbigfuture in its citations
9. B. Wang, Update on EMDrive work at NASA Eagleworks. NextBigFuture (6 February 2015). Available at: http://nextbigfuture.com/2015/02/update-on-emdrive-work-at-nasa.html;
D. Kundaliya, “EM Drive Thruster Technology: Can It Really Work?,” 2016-02-08. Available at: http://www.trinesty.com/2016/02/08/em-drive-thruster-technology-can-it-really-work/ Accessed: 4 March 2016.
The paper proposes that the thrust of EM drive results from the efflux of photons that have paired with opposite phases. The paired photons are without net electromagnetic field, and hence they will escape from the metal cavity. This loss of momentum, when anisotropic, produces the thrust. Thus, our explanation complies with conservation of momentum but departs from the current consent about photons by regarding photons as indivisible and indestructible basic building blocks of nature.
March 2016 there had been the first statement that a peer reviewed paper was coming
InMarch 2016, Nextbigfuture had reported that a peer reviewed EMDrive paper was in process
Paul March indicated on the NASA Spaceflight forum that NASA Eagleworks is getting another EMDrive paper through peer review.
Paul March also endorsed the technical information and insights of forum member Rodal on the topic of EMdrive. Rodal indicates the differences in dielectric materials and other nuances of interpreting the known results.
A radio frequency (RF) resonant cavity thruster is a proposed new type of electromagnetic thruster. Unlike conventional electromagnetic thrusters, a resonant cavity thruster would use no reaction mass, and emit no directional radiation.
A few variations on such thrusters have been proposed. Aerospace engineer Roger Shawyer designed the EmDrive in 2001, and has persistently promoted the idea since then through his company, Satellite Propulsion Research.
Chemical engineer Guido Fetta designed the Cannae Drive, based on similar principles. If they are found to work as claimed, providing thrust without consuming a propellant would have important applications to all areas of propulsion.
Some independent teams of scientists, notably a team at Xi'an's Northwestern Polytechnical University (NWPU), one at NASA's Eagleworks laboratories, and another at the Dresden University of Technology in Germany, have built prototypes of these designs. The NWPU team reported a small but significant thrust; NASA Eagleworks reported a much smaller thrust than the NWPU team; and the Dresden team reported a small thrust, but within experimental error.
In 2014 and 2015, the NASA Eagleworks research group at Johnson Space Center tested models of both the EmDrive and Cannae drive. They reported observing a small net thrust from both, at low power levels.
NASA's first tests of this tapered RF resonant cavity were conducted at very low power (2% of Shawyer's 2002 experiment and 0.7% of the Chinese 2010 experiment), but a net mean thrust over five runs was measured at 91.2 µN at 17 W of input power. A net peak thrust was recorded at 116 µN (about 0.0004 ounces, or approximately the same weight as a grain of rice) at the same power level. The experiment was criticized for not having been conducted under vacuum, which would have eliminated thermal air currents.
Six months later, early 2015, Paul March from Eagleworks made new results public, claiming positive experimental force measurements with a torsional pendulum in a hard vacuum: about 50 µN with 50 W of input power at 5.0×10^−6 torr, and new null-thrust tests. The new RF power amplifiers were said to be made for hard vacuum, but still fail rapidly due to internal corona discharges, with not enough funding to replace or upgrade them, so measurements are still scarce and need improvement before a new report can be published.
Glenn Research Center offered to replicate the experiment in a hard vacuum if Eagleworks manages to reach 100 µN of thrust, because the GRC thrust stand cannot measure forces lower than 50 µN.
Eagleworks later announced a plan to upgrade their equipment to higher power levels, use vacuum-capable RF amplifiers with power ranges of up to 125 W, and to design a new tapered cavity analytically determined to be in the 0.1 N/kW range. The test article will be subjected to independent verification and validation at Glenn Research Center, the Jet Propulsion Laboratory, and the Johns Hopkins University Applied Physics Laboratory
Previously Paul March discussed possibly scaling the Emdrive to 2000 Newtons
Paul March provides updates on the EMdrive and Cannae drive experiments at Eagleworks NASA.
If one envisions the quantum vacuum (Q-V) as a semi-virtual electrical plasma as Dr. White does, that would imply that the Poynting power flow vector would entrain the Q-V plasma and send it on its way toward the pillbox end of the cavity and then out of the cavity, the back-reaction on the cavity should be in the opposite direction towards the RF feed end of the Cannae test article, but the observed thrust vector is opposite to that surmise, i.e. toward the shorter RF sense antenna end of the cavity per the attached slide.
Now Per the newly authored Q-V plasma simulation code that Dr. White just finished, the equal bidirectional Q-V plasma flow for the Cannae cavity comes from the high-Q pancake section with a Q of ~9,000 for the un-slotted version of the cavity. However due to the high E-field region created n the throat of the RF feed, this cylindrically shaped high E-field volume acts as an obstruction to the Q-V plasma flow. This E-field obstruction created in the PTFE cylinder then accelerates the Q-V plasma around it in a Bernoulli like effect that accelerates the Q-V plasma flow coming from the main pillbox cavity. This unbalanced and accelerated Q-V plasma flow that goes away from the large pill box cavity in the direction of the RF input section is what generates the NET thrust in our model.
Next, using this new Q-V plasma simulation tool that utilizes the instantaneous E&M fields from COMSOL for one complete RF cycle in 5 degree increments as its input file, we are now seeing why we need the PTFE or HDPE dielectrics in the frustum while using near pure sine wave power levels below ~100W in the ~2.0 GHz frequency range to generate detectable thrust, and why Shawyer and the Chinese didn't while pumping 80W to 2,500W using magnetron RF sources. We think the reasons are two fold.
The first is that Shawyer and the Chinese both used magnetron RF sources for their experiments. An RF source that generates large AM, FM and PM modulation of the carrier wave with typical FM modulation bandwidth on the order of at least +/-20 MHz. (These time rate to change of energy modulations increase the Q-V density in our model.)
The second reason we found running these 3D Q-V plasma simulations for the EMPTY copper frustum, was that increasing the input power tends to focus the Q-V plasma flow from near omnidirectional from the frustum at low powers, to a much more jet like beam at higher powers measured in kW to tens of kW-rf. In fact the simulation for the 100W run predicted only ~50uN for our pure RF system with dielectric, while the 10kW run predicted a thrust level of ~6.0 Newton without a dielectric in the cavity. And at 100kW-rf it was now up to ~1300 Newton, but the input power to thrust production nonlinearity was starting to taper off around 50kW. Of course these Q-V plasma thrust predictions are based on the Q-V not being immutable and non-degradable, a feature we admit is not widely accepted by the mainstream physics community, at least at the moment.
Due to the above non-linear thrust scaling with input power predictions, we have started the build up of a 100W-to-1,200W waveguide magnetron RF power system that will drive one of our aluminum RF frustum cavities. Initially the test rig will follow Shawyer's first generation test rig that used a tetter-totter balance system in air only to see if we can generate similar thrust levels that Shawyer reported using a hermetic sealed box, which were in the ~16 to 300 milli-Newton range dependent on the Q-Factor of the frustum.
The other EMdrive experiment status
- Shawyer experiments in ambient air (as well as newer superconducting designs) are now kept under a shroud of secrecy.
- Chinese mid-to-high power experimental results (~ 2000 W) in ambient air are on the contrary regularly published in academic journals, but are still uncertain because Pr. Juan Yang is not able to share additional data, and spurious causes like air currents are not ruled-out.
There is information from Paul March on the testing of the controversial EMDrive at NASA Eagleworks. Paul commented on the NASA spaceflight forum.
SOURCES- NASA Spaceflight Forum, AIP Advances, wikipedia