Mach Effect progress

[rcain]

[]

- i am supposing that might be a progress report ....

having seen, i take that back. congrats on the patents aka 'chrismb'. will be following with great interest.

apologies for thread drift/interjection.

[DeltaV]

My guess is that we will have to apply a phase locked loop control solution between the PZT-Stack's mechanical and electrical circuits using the available stack's voltage & current waveforms AND the stack's mechanical acceleration and phasing information provides by at least two accelerometers that are embedded in the stack. I know Jim has at least one accelerometer disc embedded in the stack now, but he will need at least two to determine the order and velocity of acoustic reflections in the stack which can then be used to actively tune their magnitudes and timings so they are in synch with the stack's electrical drive signal.

New optomechanical accelerometer:
A microchip optomechanical accelerometer

This device architecture allows for full on-chip integration and achieves a broadband acceleration resolution of 10 ug/sqrt(Hz), a bandwidth greater than 20 kHz, and a dynamic range of 50 dB with sub-milliwatt optical power requirements.

In addition, nanoscale optomechanical cavities such as the zipper cavity studied here, offer the unique resource of strong radiation pressure back-action. The optical spring effect, for example, allows for dynamic tuning of the mechanical resonance frequency, which can increase the low-frequency displacement response (inverse quadratically with frequency) and decrease thermal noise (with the square root of frequency). Similar zipper cavity devices have shown low power (sub-mW) optical tuning of the mechanical resonance frequency over 10’s of MHz (> 200% of omega_m) into a regime where the mechanical structure is almost entirely suspended by the optical field [10].

[GIThruster]

Interesting. As it happens, I wrote Jim just last week with the links to the fact these stacks can have their resonance manipulated by using a DC offset. I think this was a surprise to everyone that we hadn't thought of this before. Jim actually has wired his stacks so they can be used with DC offset, so to move in that direction requires only the power system issue be solved. Unfortunately, this is almost always where the issue is. The need for a PhD EE in the lab is really the biggest need IMHO.

I'd also mention that to get the best acceleration info on these thrusters the best tool is probably a scanning laser doppler vibrometer, which is a kind of interferometer. There are many manufacturers that build them but the biggest is probably Polytech in Germany. If one wanted to go cheap here, one can forgo the scanning feature and point a compact vibrometer at the stack from outside the vacuum chamber. You're still looking at a couple thousand dollars minimum. Looks like this:

http://www.ebay.com/itm/Polytec-CLV-800 ... 0826266%26

The very best solution is to build your own extremely advanced vibrometer setup, like what they have at Aalto University in Finland.

http://www.vtt.fi/inf/pdf/publications/2011/P756.pdf

It took them many years to build this, but look at the graphics pp. 68, 77 & 78. This interferometer operates up to 6 Ghz and since these articles could operate up to 10 Ghz, this sort of equipment is what's necessary to do R&D on real world M-E thrusters. Note that this scans. What is needed is to build this such that it can be pointed at a test article while its on a thrust stand. Just needs a couple million dollars. . .

[paulmarch]

Hi Paul,

Sorry, I wasn't very clear, was I?

I remember you posting a while back that there would likely be a lot more to come once Jim got round to switching to a more promising type of cap. Do I misremember? Has Jim already switched? 150 uN is an order of magnitude above the 10-20 uN we were hearing about just a couple of months back - yes, I know it's transient, but still. How did he get there? The caps change, or simply by turning up the juice?

Kind Regards,
Ric

Looks from the pictures on NSF that a bit more effort has been spent on mechanically tuning the stack--like adding the monster reaction mass at the end.

Ric & Tom:

Dr. Woodward has been using the new Stenir & Martin SM111 PZT material for about a year now. It has higher mechanical Q and lower losses than the EDO65 PZT material that Jim had been using for these stacks up till then. I think the reason that we are now seeing ~130 uN pulses on occasion, and as Tom already pointed out, is the addition of the larger brass reaction mass. In fact Dr. Heidi Fearn who is a new CSUF co-worker with Dr. Woodward has had built a family of brass and tungsten reactions masses to see which one generates the largest thrust pulses. These activities do not address the sporadic nature of observed thrust pulses though and as I noted in an earlier post, active tuning of the PZT stack possibly with the addition of a secondary PZT tuning stack will be required to tame this issue.

Best,

A clarification to this earlier post of mine: There are two other ingredients that going to the Stenir & Martin SM111 PZT material brought to the show and that was it expressed a much larger electrostrictive signal than the EDO-65 PZT. This fact in turn generated a larger 2nd harmonic force rectification signal, which in turn generated a 4th harmonic piezoelectric signal from the V^2 electrostrictive response that produces and even larger mass fluctuation signal that is then force rectified by the electrostrictive induced 8th harmonic, etc. Add yes, the higher harmonics have much lower amplitudes than the lower harmonic signals, but since the M-E signal in these PZT-Stacks scales with the drive frequency to the 6th power, the 4th harmonic driven M-E signal is multiplied by a factor of 4^6 = 4,096 which more than compensates for the order of magnitude plus reduction in the 4th harmonic signal amplitude. Thus we see how Woodward's PZT-Stack can go from producing 2 uN up to 130 uN when the 4th harmonic M-E signal can be expressed. In other words the change to a larger reaction mass didn't add much to the thrust improvement in and of itself, but it did increase the magnitude of the 4th harmonic production, which was the key element in this almost two orders of magnitude thrust increase.

Of course these results indicate that one should be driving these PZT stacks not at the 30 kHz frequency as Woodward is doing now, but at least at 500 kHz, which will yield a thrust increase factor of at least (500/30)^6 = 21,433,471 x 2 uN = ~43 Newtons with all else being equal, even if we don't excite the 4th harmoinc of that signal...

Best,

[ladajo]

Paul,
Does he have to drive the stack with an oscillator? Can he rig it to be driven by an external RF Cavity?
Just thinking out loud.

[paulmarch]

Paul,
Does he have to drive the stack with an oscillator? Can he rig it to be driven by an external RF Cavity?
Just thinking out loud.

Ladajo:

I guess the PZT stack could be driven by an external RF Cavity, but if we are talking about a resonant RF cavity, think about the size it would be at 30 kHz if it was not dielectrically loaded, and even then its going to be very large. I think Woodward is better off sticking with his current approach to excitation until he moves up in operating frequency.

Best,

[ladajo]

Yes, I was thinking on higher freqs. He may be able to pick a lower harmonic for useful driving.

Thinking ahead.

[GIThruster]

Just by way of update, looks like the core discipline for creating UFG thrusters is already being developed this last 10 years or so in the work concerning FBAR's or thin Film Bulk Acoustic Resonators. There is a ton of detailed info on this work available on the web especially including how to design and build Bragg reflectors--all important for future work.

And just to note, Jim's seminal work will be published in the next week or two. Get your copy set aside at discount by ordering before its published:

http://www.amazon.com/Making-Starships- ... 1461456223

All proceeds go directly to future research in exotic propulsion through the auspices of the Space Sciences Institute. Jim doesn't earn a penny for all the work he's done on this the last year.

And consider who would make best use of this historic accomplishment by thinking on the list of those you might send the book to--Kip Thorne, Neil deGrasse Tyson, Michio Kaku, all have earned a copy. Who do you think needs to read the blueprint for stellar exploration?

[ScottL]

So what's the time table for a possible and more obvious test device? I like hearing updates and reading over the work cited, but as I'm not in the loop, I am curious. The rammifications seem pretty enormous. Also, what were the results with the warp field tests and such from Paul/Sonny? Thanks in advance.

[GIThruster]

Jim hasn't said what he plans for a next device. I know his coworker Heidi Fern wants to move on to larger thrusts. Usually though, the work is hampered mainly by power system constraints. It is the power system that requires the most effort and any future high-performance thruster system needs a completely new system as it would be higher frequency. So I do't think that's necessarily on the table at the moment. I think rather Jim may decide to tinker with what he has and demonstrate better mastery over force generation. Working out all the details of the "just so conditions" will be of great use later on.

Jim does have some specially built power equipment from Dr. Long that he intends to install but hasn't gotten to that yet. I am not sure, but I think that may be a 2 frequency power matcher that will enable Jim to put the power at both frequencies in phase for the first time. That could be a big step forward.

I've no idea what's going on down at Eagleworks. I didn't expect them to attempt anything before the 100YSS conference last month as a null result would have been a wet blanket for them at the conference. I think though when they get something worth reporting you can expect Paul to post about it here at T-P.

[AcesHigh]

The downside of warp drives: Annihilating whole star systems when you arrive

http://www.extremetech.com/extreme/1406 ... you-arrive

"...- As your faster-than-light ship sails through the cosmos, it’s not alone. Although we often think of space as empty, there are loads of high-energy particles shooting through the void. The University of Sydney research indicates that these particles are liable to get swept up in the craft’s warp field and remain trapped in the stable bubble. The longer the journey lasts, the more of these dangerous particles build up. This doesn’t affect the ability of the warp drive to keep bending the laws of the universe — it’s the stopping that’s going to ruin your day.

- The instant the Alcubierre drive is disengaged, the space-time gradient that allows it to effectively move faster than light goes away. All the energetic particles trapped during the journey have to go somewhere, and the researchers believe they would be blasted outward in a cone directly in front of the ship. Anyone or anything waiting for you at the other end of your trip would be destroyed. Because of a funny little quirk of relativity, there is no upper limit to the amount of energy a Alcubierre drive could pick up. A long trip could vaporize entire planets upon your arrival.

..."

[Skipjack]

Solution:
Disengage the warp drive frequently and then reengage it.

[williatw]

Solution:
Disengage the warp drive frequently and then reengage it.

Or just disengage the warp drive when you are say a few hundred or thousand AU's away from your destination planet, and make sure the "cone" of particles is blasted in a safe direction. Then proceed the rest of the way on your Fusion or "mach thruster" drive. After all you would need distance & time to decelerate anyway, after you disengaged the drive, the other issue with the energized particles notwithstanding.

[Skipjack]

Well if you disengage the Warp drive often enough, it wont have time to pick up enough energetic particles to do any harm anyway.

[williatw]

Well if you disengage the Warp drive often enough, it wont have time to pick up enough energetic particles to do any harm anyway.

Assuming there is no problem with repeatedly engaging and disengaging the drive you would be right. Take it a step further, at some point someone would figure out a way of harnessing this waste energy....some kind of backstop at your destination point. The particle flux hitting a Tungsten backstop making antimatter, or some kind of ring or coil making electricity from the high energy charged particles. Probably 100's or maybe even thousands of Terajoules worth of energetic particles swept up in the warp field during long several hundred light year trips waiting to be harvested.