July 31, 2014

Renewed hope for EmDrive with NASA validation ... is this a Chicago Pile moment ?

We are getting new Star Wars movies. Blacklight Power is back and claiming they have made breakthroughs which overcome past problems.

The Chicago Pile was the first artificial nuclear reactor. The first man-made self-sustaining nuclear chain reaction was initiated in CP-1 on 2 December 1942, under the supervision of Enrico Fermi. Fermi described the apparatus as "a crude pile of black bricks and wooden timbers." Made of a large amount of graphite and uranium, with "control rods" of cadmium, indium, and silver, unlike most subsequent reactors, it had no radiation shield and no cooling system.

A Chicago Pile moment is when a radical new technology achieves technological takeoff.

I have background on what EmDrive would mean below from articles in 2009. Success and validation that aligns with what is believed about EmDrive means powerful mainly static thrust. It would be an alternative way to achieve effects that would mimic antigravity. It would enable super efficient planes, better flying cars, and cloud city like applications in a full expression of a mature EmDrive. In the nearer term it would be better satellite propulsion.

a US scientist, Guido Fetta, has built his own propellant-less microwave thruster, and managed to persuade Nasa to test it out. The test results were presented on July 30 at the 50th Joint Propulsion Conference in Cleveland, Ohio. Astonishingly enough, they are positive.

The Nasa team based at the Johnson Space Centre gave its paper the title "Anomalous Thrust Production from an RF [radio frequency] Test Device Measured on a Low-Thrust Torsion Pendulum". The five researchers spent six days setting up test equipment followed by two days of experiments with various configurations. These tests included using a "null drive" similar to the live version but modified so it would not work, and using a device which would produce the same load on the apparatus to establish whether the effect might be produced by some effect unrelated to the actual drive. They also turned the drive around the other way to check whether that had any effect.

Last year a Chinese team built its own EmDrive and confirmed that it produced 720 mN (about 72 grams) of thrust, enough for a practical satellite thruster. Such a thruster could be powered by solar electricity, eliminating the need for the supply of propellant that occupies up to half the launch mass of many satellites. The Chinese work attracted little attention; it seems that nobody in the West believed in it.

Fetta also presented a paper at AIAA on his drive, "Numerical and Experimental Results for a Novel Propulsion Technology Requiring no On-Board Propellant". His underlying theory is very different to that of the EmDrive, but like Shawyer he has spent years trying to persuade sceptics simply to look at it. He seems to have succeeded at last.

Shawyer himself, who sent test examples of the EmDrive to the US in 2009, sees the similarity between the two.

"From what I understand of the Nasa and Cannae work -- their RF thruster actually operates along similar lines to EmDrive, except that the asymmetric force derives from a reduced reflection coefficient at one end plate," he says. He believes the design accounts for the Cannae Drive's comparatively low thrust: "Of course this degrades the Q and hence the specific thrust that can be obtained."

Fetta is working on a number of projects which he is not able to discuss at present, and Nasa's PR team was not able to get any comments from the research team.

Abstract - Anomalous Thrust Production from an RF Test Device Measured on a Low-Thrust Torsion Pendulum

This paper describes the eight-day August 2013 test campaign designed to investigate and demonstrate viability of using classical magnetoplasmadynamics to obtain a propulsive momentum transfer via the quantum vacuum virtual plasma. This paper will not address the physics of the quantum vacuum plasma thruster, but instead will describe the test integration, test operations, and the results obtained from the test campaign. Approximately 30-50 micro-Newtons of thrust were recorded from an electric propulsion test article consisting primarily of a radio frequency (RF) resonant cavity excited at approximately 935 megahertz. Testing was performed on a low-thrust torsion pendulum that is capable of detecting force at a single-digit micronewton level, within a stainless steel vacuum chamber with the door closed but at ambient atmospheric pressure. Several different test configurations were used, including two different test articles as well as a reversal of the test article orientation. In addition, the test article was replaced by an RF load to verify that the force was not being generated by effects not associated with the test article. The two test articles were designed by Cannae LLC of Doylestown, Pennsylvania. The torsion pendulum was designed, built, and operated by Eagleworks Laboratories at the NASA Johnson Space Center of Houston, Texas. Approximately six days of test integration were required, followed by two days of test operations, during which, technical issues were discovered and resolved. Integration of the two test articles and their supporting equipment was performed in an iterative fashion between the test bench and the vacuum chamber. In other words, the test article was tested on the bench, then moved to the chamber, then moved back as needed to resolve issues. Manual frequency control was required throughout the test. Thrust was observed on both test articles, even though one of the test articles was designed with the expectation that it would not produce thrust. Specifically, one test article contained internal physical modifications that were designed to produce thrust, while the other did not (with the latter being referred to as the "null" test article). Test data gathered includes torsion pendulum displacement measurements which are used to calculate generated force, still imagery in the visible spectrum to document the physical configuration, still imagery in the infrared spectrum to characterize the thermal environment, and video imagery. Post-test data includes static and animated graphics produced during RF resonant cavity characterization using the COMSOL Multiphysics® software application. Excerpts from all of the above are included and discussed in this paper. Lessons learned from test integration and operations include identification of the need to replace manual control of the resonant cavity target frequency with an automated frequency control capability. Future test plans include the development of an automatic frequency control circuit. Test results indicate that the RF resonant cavity thruster design, which is unique as an electric propulsion device, is producing a force that is not attributable to any classical electromagnetic phenomenon and therefore is potentially demonstrating an interaction with the quantum vacuum virtual plasma. Future test plans include independent verification and validation at other test facilities.

Back to 2009

A Nextbigfuture review of emdrive in 2009

A link to the 14 page word document on the 2009 EMDrive research

Wired has details on the EMDrive presentation.

The heart of the Emdrive is a resonant, tapered cavity filled with microwaves. According to Shawyer, a relativistic effect generates a net thrust, an effect confirmed by various Emdrives he has built as demonstrations. Critics say that any thrust from the drive must come from another source. Shawyer is adamant that the measured thrust is not caused by other factors.

Previous thrusters generated relatively modest forces; the latest version now being built is based on a cooled superconductor and should generate more than 300 pounds of thrust for a 6-kilowatt input, Shawyer promises. (But does not yet appear to have done so.) The plan is to mount four of these thrusters on an unmanned demonstration vehicle that will weigh about 1,000 pounds. The craft will have no wings: It will be supported by the Emdrives and propelled by jet engines to about 230 knots. It will be capable of vertical takeoff and hovering silently in place. If successful, it will be adapted as a personal transport -– your very own flying car.

In the longer run, perhaps 10 years, Shawyer envisages a hybrid spaceplane using Emdrive technology — see the photo above of a 2-meter scale model. The idea is a craft capable of making the 10,000-mile run from London to Sydney, Australia in under three hours … or taking a 40-ton payload on the moon in about four days.

The EMdrive enables superconducting cavities to very efficiently create static thrust. Thrust is measured in "pounds of thrust" in the U.S. and in Newtons under the metric system (4.45 Newtons of thrust equals 1 pound of thrust). 300 pounds of thrust is 1335 Newtons of thrust. 6 kilowatts of input means that 222.5 N/kW.

Apparently the 6.8 million Q device has 143 kg opf thrust from 6 kW input.

Effect of increased Q for the Emdrive
Q=50,000 (1st gen.)  Static thrust=315 mN/kW   Specific thrust at 3km/s=200mN/kW

Q=6,800,000 (supercond) Static thrust=222 N/kW Specific thrust at ??km/s=??N/kW

Q=5* 10**9 (supercond) Static thrust=31.5 kN/kW Specific thrust at 0.1km/s=8.8N/kW

Q=10**11 (supercond) Static thrust=630 kN/kW Specific thrust at 0.1km/s=??N/kW

Very high Q superconducting cavities would allow more static lift. Making multi-billion Q factor cavities and working EMdrive would enable cloud cities and long duration/near permanent flying platforms for antennas, weapons and other purposes.

High Power Density Power Sources

Very high power to weight ratio could be used to power station keeping in space or even provide the equivalent of antigravity. There are ultrathin solar arrays.

Current results of 5,880 Watts per kilogram at 7-9 micron polymer.

16,800 Watts kilogram for 2 micron thickness polymer at 168 Watt/m2
AMO Standard 1357 W/m2 @ +90°C, 12.4% efficient, a-Si:H cells.
Power density over 10,000 Watts per kg for European Sail Tower SPS Concept.
a-Si:H cells on 2 micron NASA CP1 or M-SRS CORIN Polyimide

Superconducting Cavities if EMDrive Works

Operating at temperatures just above absolute zero, superconducting cavities accelerate bunches of electrons and positrons toward the detectors in a proposed international linear collider. Nine smooth cells, polished in all possible ways. Made of the purest niobium. Not a speck of dust or the slightest difference in shape. Superconducting when supercold Photo: Fermilab

Superconducting cavities are a key component of an enhanced version of the controversial Emdrive [electromagnetic drive].

Prototype C-band emdrive (The emdrive has been funded by China and could be a breakthrough in space and terrestrial propulsion or it is a one to two million dollar scientific mistake.) [by the cinderblock in the background it appears to be less one foot tall]

Effect of increased Q for the Emdrive
Q=50,000 (1st gen.)  Static thrust=315 mN/kW   Specific thrust at 3km/s=200mN/kW

Q=6,800,000 (supercond) Static thrust=42.8 N/kW Specific thrust at ??km/s=??N/kW

Q=5* 10**9 (supercond) Static thrust=31.5 kN/kW Specific thrust at 0.1km/s=8.8N/kW

Q=10**11 (supercond) Static thrust=630 kN/kW Specific thrust at 0.1km/s=??N/kW

SPR ltd is working on a superconducting demo which should be 100 times more powerful than the first version and provide 30 newtons of force instead of 315 milli-newtons. China is also building a large S-band thruster.

Superconducting radiofrequency (SCRF) cavities are also the main technology for a new international linear collider.

The main vehicle for SCRF technology is the cavity, a hollow structure that drives particles to higher energies. For the ILC, we will use roughly 16,000 metre-long nine-cell 1.3 GHz (gigahertz) niobium cavities. So far ILC scientists have achieved the target gradient goal in roughly a dozen cavities. “We have proven that the technology works,” says Cornell University’s Hasan Padamsee. “Now we need to improve the yield.” In some cases, ILC cavities have actually exceeded the
target goal and reached a gradient of 40 MV/m. Consistently reaching a gradient of 35 MV/m, however, in a large number of cavities remains a problem.

The European Commission has accepted to fund the ILC-HiGrade, or “International Linear Collider and High Gradient Superconducting RF-Cavities,” proposal within its Seventh Framework Programme (FP7) with five million Euros over the next four years. Under this contract, at least 24 superconducting cavities will be created to demonstrate the gradient feasibility for the ILC.

This kind of superconductivity cavity would be one thousand to twenty thousand times better than the crude superconducting demo that SPR ltd currently has. A very good nobium cavity could probably be created for $400,000 to 800,000 [converting the Euro price to dollars and increasing the cost for one instead of 24].

A 2002 study of superconducting cavity costs worked out to $100,000 per meter.

In the same 2002 presentation by Pierre Bauer, it appears that the maximum Q value is at least higher than 100 billion for certain kinds of nobium cooled to about 1 degree kelvin.

Possible research for higher Q cavities [2002 list]:
1) cavity manufacturing (“seam-less” techniques such as hydro-forming,…)
2) materials – e.g. replacing bulk Nb with Nb on Cu
3) surface resistance – e.g. understanding the surface chemistry that leads to low surface resistance, exploring materials which produce lower surface resistance,..etc
4) Higher gradients in view of a second stage in the same tunnel – e.g. pushing Nb to the absolute limit, exploring other materials such as Nb3Sn and NbN;

This dynamic test rig moved at 2 cm per second using the first generation emdrive. If the crude superconducting test system can be made to work then it should move the a heavier (ten tons instead of 100kg) dynamic test rig at 2 cm per second [the system loses energy with more speed].

A couple million dollars of equipment and labor at risk over two years to verify what could be a huge multi-trillion dollar breakthrough or a fairly cheap mistake (or something inbetween).

Superconducting Radio Frequency at wikipedia

It is commonplace for a 1.3 GHz niobium SRF resonant cavity at 1.8 Kelvin to obtain Q=5×10**10 [50 billion]. Such a very high Q resonator and its narrow bandwidth can then be exploited for a variety of applications. At present, none of the "high Tc" superconducting materials are suited for RF applications. Shortcomings of these materials arise due to their underlying physics as well as their bulk mechanical properties not being amenable to fabricating accelerator cavities.

If you liked this article, please give it a quick review on ycombinator or StumbleUpon. Thanks
blog comments powered by Disqus