Author Topic: EM Drive Developments - related to space flight applications - Thread 2  (Read 2165586 times)

Offline Rodal

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....

Did you or anyone else ever write an excel spreadsheet to calc Shawyers Design Factor? If so pls link it or if not please consider doing it as your skills there are much better than mine.
Yes I have calculated it, but it is a Mathematica program, not an Excel spreadsheet.  I posted (earlier in the thread) comparisons of the measurements vs. predictions using Shawyer's and McCulloch's formulas.

You may want to PM @aero to ask whether he did it with Excel (if my memory is correct @aero also calculated Shawyer's Design Factor, as I recall having exchanges in this forum with him).

And of course, when running your program, you will first check your results vs. Shawyer's published Design Factor results, etc., to make sure that your program is correct.
« Last Edit: 05/07/2015 08:06 PM by Rodal »

Offline Rodal

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The point I'm making is this. You see these men sitting at the table together in this video? They're all on the same team....trying to figure out how to pull off interstellar flight. For the good of all of us. Now they're duking it out in an interview in Wired. They (like us) should all be working together, pooling resources, combined knowledge and experience. Instead a rift has formed, which will likely kill progress.

it seems to me Wired totally distorted what Davis and Millis said. Most comments also note that.
That's why everybody would be well-advised never to talk to reporters, unless they can be assured in writing by the reporter that nothing will get published without their prior approval   ;)
« Last Edit: 05/07/2015 08:08 PM by Rodal »

Offline TheTraveller


I've been looking at surplus 20kw radar magnetrons on ebay, and the availability of 3D printed silicons carbide base on which to plate my Magnesium diboride superconductor, and also at cryocoolers. It's all very complex and expensive, and with the cryo, somewhat dangerous. I am most definitely in the realm of a 'hacker' in this endeavor (and have been so in other fields for a number of years), so I know what to expect (or at least I think I do).

Radar magnetrons operate in pulsed mode.    The output power during the pulse may be 20 kW but the duration is very short and so the average power output is very low.   Any high power CW magnetron is very dangerous to play with when it is removed from the equipment it was designed for.    The RF discharges can cause serious injury and temporary blindness.
Yup.

Was one of the reasons I went with a programmable narrow band RF generator and separate solid state RF power amplifier, all connected together with coax & twist lock / screw on connectors. Plus this was what Shawyer did for his Flight Thruster. Except he used a Travelling Wave Tube RF amplifier as he had to interface with existing space rated gear.

Bottom line, keep it KISS and follow what has been done before.

In his latest superconducting tests, note the use of coax and a programmable RF generator.

Should add Shawyer's development path is not to use massive RF power, but to increase the cavity Q, via superconducting cavity and thus to cause a massive increase in thrust, with no need to increase cavity RF power input.

So higher cavity Q and lower power is expected to give a better result than using lower cavity Q and higher power. Which is why I'm replicating the Flight Thruster and designing to use spherical concave / conver end plates so as to get the highest cavity Q I can.
"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.”
Herman Melville, Moby Dick

Offline MrVibrating

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@TheTraveller

I know the guy with the magnetic bearing in that vid you posted - a bloke called Craigy, now works out of a private R&D lab in east London.  We were both members of Steorn's SKDB (aka "The Spudclub") and what you see in the video is a rough draught of one of Steorn's low-friction bearings, a design that came to be known as "nero zero" for its low friction (not to be confused with their patented Earnshaw-defying "Zero-F" bearings which are entirely non-contact passive bearings).

The basic design for a nero zero bearing is pretty much what you see there, although can be improved by using a diametrically-polarised NdFeB disc magnet on the bottom of the vertical shaft, levitating above a toroidal NdFeB - ideally of N42 grade or better if possible.  The top of the shaft tapers to a needle, resting in a jewel cup.  The jewel is affixed to the underside of a micrometer head, so that the ride height of the whole shaft + disc magnet assembly can be adjusted over the ring magnet stator; this allows accurate tuning of stability vs friction.  I actually still have one here lying around...   we used to test them in terms of their wind-down period, and a well set up rig weighing a just a couple of hundred grams can easily achieve wind-downs of 10 minutes from 1,000 rpm.

The fully Zero-F bearings (no contact) are slightly more complex, using a mixture of paramegnetic and ferromagnetic materials - hence why they're not truly Earnshaw-exceptions, although they achieve the same end - but the nero-zero articles are good enough for measuring in the nJ range..  We used to use laser tachos, establish the MoI and baseline loss rates then calculate magnetic interaction efficiencies from there...  You can find everything cheap on eBay, and even get magnets made to your own specs for very little..

Offline R.W. Keyes

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I think that the solution is really simple, if it's about demonstrating a thrust effect that is many times larger than measurement precision: Crank up the RF power. A lot. There is really no two ways about it. Please don't even try to play with a power level that even a 9V-battery can put out.. . Personally, I'd play in a power regime of about 1kW (actually I do, but that's another story..) . 1KW is a level that can easily be handled by readily available parts and off-the-shelf electronics, but is still not excessive.

How about using Tesla batteries for a few seconds (>300 KW?) and send the damn thing at the other side of the galaxy? Would that form a convincing test result?
From what I distill from some of the information I have read, coronal discharges were already plaguing some of the teams at power between 100 and 1000 Watts. a 300KW burst would probably fry everything we can throw at it and would require serious re-design of the components and use of materials, if at all possible.
The problems with coronal discharges were with amplifiers. Magnetrons aren't affected by this, as they have no capacitors.
Tesla's batteries are unobtanium for the next year, it appears, so I am not even evaluating them at this stage.

Offline R.W. Keyes

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I've been looking at surplus 20kw radar magnetrons on ebay, and the availability of 3D printed silicons carbide base on which to plate my Magnesium diboride superconductor, and also at cryocoolers. It's all very complex and expensive, and with the cryo, somewhat dangerous. I am most definitely in the realm of a 'hacker' in this endeavor (and have been so in other fields for a number of years), so I know what to expect (or at least I think I do).

Radar magnetrons operate in pulsed mode.    The output power during the pulse may be 20 kW but the duration is very short and so the average power output is very low.   Any high power CW magnetron is very dangerous to play with when it is removed from the equipment it was designed for.    The RF discharges can cause serious injury and temporary blindness.

I hadn't known about their pulsed nature, but that makes sense. This doesn't make them useless, but does limit the application. I am thinking I should start with low power magnetrons. I understand that RF at this wavelength and power are dangerous, and I would certainly take much caution in its use. But certainly, lower power is going to give some safety margin.

You can actually be killed by microwaves. I have heard stories about Navy accidents...

Offline R.W. Keyes

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I think that the solution is really simple, if it's about demonstrating a thrust effect that is many times larger than measurement precision: Crank up the RF power. A lot. There is really no two ways about it. Please don't even try to play with a power level that even a 9V-battery can put out.. . Personally, I'd play in a power regime of about 1kW (actually I do, but that's another story..) . 1KW is a level that can easily be handled by readily available parts and off-the-shelf electronics, but is still not excessive.
Which battery types would you recommend for 1 KW operation?

I personally use LiFePO4 batteries, as they are inherently safer than alternatives. For instance, I have one (about 1kg) with 8400mAh capacity and 30C continuous discharge capability (252 amps). You can extract ~1kW for a couple minutes, which should be enough for measurements. Recharging is also fast.

LiFePO4 is a good battery tech..better, safer than others out there though not quite as much power/mass. For short tests, I think that whatever can be effectively used is good. For actual vehicles, where safety and reliability is required, I'd want LiFePO4.

Regarding your earlier comments, about just using more power to get results: I think we're going to see two different methodologies here,  the first being what Eagleworks is doing, which is carefully thought out, precision science, with work on theory to explain and therefore maximize efficiency. The other approach is the hacker approach, which is more of a mechanical and pragmatic approach, of doing things like applying more power or using different materials based upon hunches...that the proof will be in the pudding, so to speak. The problems arise when trying to unify the approaches - without some really fantastic results (such as a flying car), no one is going to let a hacker near the precision and certified labs to prove their claims, and the naysayers will have a field-day with "outlandish claims". Much of the guff EMdrive etc have received so far is because of insufficient theory and tests. I don't have a PhD in physics, and even if I did, if I wasn't prominent in the field I'd see no reason why Eagleworks or other reputable places would waste their time with me or the hundred other 'crackpots' in serious tests.

The exception to this may be if a program were implemented for inexpensive, quick, formal tests. An example which passed these tests would then be eligible for further testing and scrutiny. I think that such a program would be the best interface between the 'hackers' and the 'scientists'.

I've been looking at surplus 20kw radar magnetrons on ebay, and the availability of 3D printed silicons carbide base on which to plate my Magnesium diboride superconductor, and also at cryocoolers. It's all very complex and expensive, and with the cryo, somewhat dangerous. I am most definitely in the realm of a 'hacker' in this endeavor (and have been so in other fields for a number of years), so I know what to expect (or at least I think I do).
My engineer's gut tells me the best device for "Replicators" would be the Flight Thruster as it uses narrow band RF, which can be generated by a programmable RF generator, with an auxiliary RF amplifier and the RF energy feed into the cavity by standard RF connectors and coax. This gives good control over both frequency and power, which is not really available with a magnetron based RF generator, plus stops the need to add waveguides into the build.

I'm doing as close as possible to Shawyer replication as I can as I feel the closer I stay to Shawyer, the higher the chance of success. WHEN that works I may start trying stuff outside what Shawyer has shared.
The nice thing about magnetrons is you get a lot of power without having to use an amplifier, and hence capacitors, which don't behave well in vacuum. Of course, if you're not worried about tests in a vacuum, then something less of an RF sledgehammer, some RF signal generator with more finesse, has advantages. But, amplification becomes expensive. TWTs (Travelling Wave Tubes) are more expensive that Magnetrons. I intend to used both approaches, but will probably start with the Magnetron, in an attempt to replicate Shawyer's work, before I do anything else.

Offline TheTraveller

....

Did you or anyone else ever write an excel spreadsheet to calc Shawyers Design Factor? If so pls link it or if not please consider doing it as your skills there are much better than mine.
Yes I have calculated it, but it is a Mathematica program, not an Excel spreadsheet.  I posted (earlier in the thread) comparisons of the measurements vs. predictions using Shawyer's and McCulloch's formulas.

You may want to PM @aero to ask whether he did it with Excel (if my memory is correct @aero also calculated Shawyer's Design Factor, as I recall having exchanges in this forum with him).

And of course, when running your program, you will first check your results vs. Shawyer's published Design Factor results, etc., to make sure that your program is correct.
Mathematica looks interesting but maybe later as I suspect there would be a learning curve.

Is this still your Design Factor equation?

Thanks for your assistance. Most appreciated.
"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.”
Herman Melville, Moby Dick

Offline R.W. Keyes

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I wonder if some of us who are closeby each other would want to meet up to discuss the concepts, and perhaps team up to build. I am currently in Pittsfield, Massachusetts, so it easy for me to drive to Albany, Springfield, Worcester, or Hartford to meet. Boston is a bit more of a stretch. I'll be on vacation in Ireland in the beginning of June, so I may be able to meet people there.

I presently own an industrial building of moderate size (4000sf+attached 2200sf house) which I have considered selling, but perhaps it would make an adequate workshop for emdrive experiments. It needs some work, however.

EDIT I also like the idea of sharing compute power, and computer resources in general. I have a moderately fast Linux machine with 24GB of ram that I could share, in addition to a bunch of older machines (but is the electric consumption worth the CPU power they could provide?) I may also be able to get a COMSOL license (very uncertain at this point), but I have no idea how to run it.
« Last Edit: 05/07/2015 09:01 PM by R.W. Keyes »

Offline zen-in

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The problems with coronal discharges were with amplifiers. Magnetrons aren't affected by this, as they have no capacitors.
Tesla's batteries are unobtanium for the next year, it appears, so I am not even evaluating them at this stage.

RF arcing occurs with any kind of RF amplifier if the load is not matched.   It has nothing to do with capacitors.    When the amplifier experiences a high SWR power is reflected back to the amplifier.   This creates a standing wave on the feedline.    The high voltages present on the feedline can destroy a solid state amplifier.    Tube amplifers are more resistant to this kind of damage and often provide a visual indication; but internal arcing can destroy them as well.    The main problem is that the cavity's high Q (several 100k or k depending on how it is measured ;)) means it is next to impossible to tune the drive to resonance.   So most of the power is reflected.    This is especially a problem in a vacuum.
« Last Edit: 05/07/2015 09:02 PM by zen-in »

Offline TheTraveller

@TheTraveller

I know the guy with the magnetic bearing in that vid you posted - a bloke called Craigy, now works out of a private R&D lab in east London.  We were both members of Steorn's SKDB (aka "The Spudclub") and what you see in the video is a rough draught of one of Steorn's low-friction bearings, a design that came to be known as "nero zero" for its low friction (not to be confused with their patented Earnshaw-defying "Zero-F" bearings which are entirely non-contact passive bearings).

The basic design for a nero zero bearing is pretty much what you see there, although can be improved by using a diametrically-polarised NdFeB disc magnet on the bottom of the vertical shaft, levitating above a toroidal NdFeB - ideally of N42 grade or better if possible.  The top of the shaft tapers to a needle, resting in a jewel cup.  The jewel is affixed to the underside of a micrometer head, so that the ride height of the whole shaft + disc magnet assembly can be adjusted over the ring magnet stator; this allows accurate tuning of stability vs friction.  I actually still have one here lying around...   we used to test them in terms of their wind-down period, and a well set up rig weighing a just a couple of hundred grams can easily achieve wind-downs of 10 minutes from 1,000 rpm.

The fully Zero-F bearings (no contact) are slightly more complex, using a mixture of paramegnetic and ferromagnetic materials - hence why they're not truly Earnshaw-exceptions, although they achieve the same end - but the nero-zero articles are good enough for measuring in the nJ range..  We used to use laser tachos, establish the MoI and baseline loss rates then calculate magnetic interaction efficiencies from there...  You can find everything cheap on eBay, and even get magnets made to your own specs for very little..
Thanks for that info.

Will do a bit of research and yes EarnShaw is like Murphy. Party spoilers.
"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.”
Herman Melville, Moby Dick

Offline TheTraveller


The problems with coronal discharges were with amplifiers. Magnetrons aren't affected by this, as they have no capacitors.
Tesla's batteries are unobtanium for the next year, it appears, so I am not even evaluating them at this stage.

RF arcing occurs with any kind of RF amplifier if the load is not matched.   It has nothing to do with capacitors.    When the amplifier experiences a high SWR power is reflected back to the amplifier.   This creates a standing wave on the feedline.    The high voltages present on the feedline can destroy a solid state amplifier.    Tube amplifers are more resistant to this kind of damage and often provide a visual indication; but internal arcing can destroy them as well.    The main problem is that the cavity's high Q (several 100k or k depending on how it is measured ;)) means it is next to impossible to tune the drive to resonance.   So most of the power is reflected.
Which is why using a programmable RF generator that also allows output level to be varied, allows use of low power to lock the RF frequency to the cavity and then slowly increase power as you continue to seek cavity lock.

In Shawyers 1st 2 units, the Feasibility and the Demonstrator devices, the cavity was physically tuned to the RF signal, a magnetron. You can listen to Shawyer saying the initial part of the rotary Demonstrator test produced no thrust until the magnetron LOCKED to the cavity. I suspect what really happened was the stepper motor at the small end of the cavity, mechanically tuned the cavity to the magnetron frequency and then thrust happened.

Look at the gears and stepper motors fitted to the small end of the Demonstrator EM Drive. Very clever mechanics but not needed if you use a narrow band programmable RF source and use spherical end plates.

Shawyer learned much from his 1st 2 EM Drives and applied it all to the Flight Thruster. No physical cavity tuning needed as he used a programmable RF generator which feeds a RF amplifier. Plus he uses a sensor in the big end to provide feedback for his frequency control loop to ensure the cavity Rf frequency is always at the right frequency to dump the max RF energy into the cavity to generate the max thrust.

as an engineer, I look at the development history and my guts says, good job Mr Shawyer.
"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.”
Herman Melville, Moby Dick

Offline Rodal

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....

Did you or anyone else ever write an excel spreadsheet to calc Shawyers Design Factor? If so pls link it or if not please consider doing it as your skills there are much better than mine.
Yes I have calculated it, but it is a Mathematica program, not an Excel spreadsheet.  I posted (earlier in the thread) comparisons of the measurements vs. predictions using Shawyer's and McCulloch's formulas.

You may want to PM @aero to ask whether he did it with Excel (if my memory is correct @aero also calculated Shawyer's Design Factor, as I recall having exchanges in this forum with him).

And of course, when running your program, you will first check your results vs. Shawyer's published Design Factor results, etc., to make sure that your program is correct.
Mathematica looks interesting but maybe later as I suspect there would be a learning curve.

Is this still your Design Factor equation?

Thanks for your assistance. Most appreciated.




I recognize that equation is my Mathematica-writing, but I need a link to the message where I posted it, in order to remember the context.  Too long ago  :)
« Last Edit: 05/07/2015 09:59 PM by Rodal »

Offline deltaMass

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@TheTraveller
A small, slow-speed generator with magnetic bearings is I think what you need. I have looked but so far had no luck. One can find them in profusion, however, for direct drive power generation from a wind power machine. These are of course massive and expensive.

Offline WarpTech

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Latest paper by Dr. White, on http://ntrs.nasa.gov/ , exploring the idea of the quantum vacuum not being an absolute immutable and nondegradable state, and examining  some rami cations of the quantum vacuum being able to support non-trivial spatial variations in density.  They claim that their "considerations showed no predictions that were contrary to observation, and in fact duplicated predictions for energy states associated with the primary quantum number."

http://hdl.handle.net/2060/20150006842

Dynamics of the Vacuum and Casimir Analogs to the Hydrogen Atom
Harold White, Jerry Vera,y Paul Bailey,z Paul March,x Tim Lawrence,{ Andre Sylvester, and David Brady
NASA Johnson Space Center
2101 NASA Parkway, Houston, TX 77058
(Dated: April 2, 2015)

Publication Date:   Apr 02, 2015
Document ID:   
20150006842 (Acquired Apr 28, 2015)
Subject Category:   PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; ATOMIC AND MOLECULAR PHYSICS; NUMERICAL ANALYSIS; COMPUTER PROGRAMMING AND SOFTWARE
Report/Patent Number:   JSC-CN-33080
Document Type:   Technical Report
Financial Sponsor:   NASA Johnson Space Center; Houston, TX, United States
Organization Source:   NASA Johnson Space Center; Houston, TX, United States
Description:   9p; In English

There is an error in the integration of equation 11. Apparently their "simple enough" integration was not simple enough!


Offline zen-in

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Which is why using a programmable RF generator that also allows output level to be varied, allows use of low power to lock the RF frequency to the cavity and then slowly increase power as you continue to seek cavity lock.

In Shawyers 1st 2 units, the Feasibility and the Demonstrator devices, the cavity was physically tuned to the RF signal, a magnetron. You can listen to Shawyer saying the initial part of the rotary Demonstrator test produced no thrust until the magnetron LOCKED to the cavity. I suspect what really happened was the stepper motor at the small end of the cavity, mechanically tuned the cavity to the magnetron frequency and then thrust happened.

Look at the gears and stepper motors fitted to the small end of the Demonstrator EM Drive. Very clever mechanics but not needed if you use a narrow band programmable RF source and use spherical end plates.

Shawyer learned much from his 1st 2 EM Drives and applied it all to the Flight Thruster. No physical cavity tuning needed as he used a programmable RF generator which feeds a RF amplifier. Plus he uses a sensor in the big end to provide feedback for his frequency control loop to ensure the cavity Rf frequency is always at the right frequency to dump the max RF energy into the cavity to generate the max thrust.

as an engineer, I look at the development history and my guts says, good job Mr Shawyer.

It makes for an interesting theory as to why Shawyer's results were so much better than EW.  Earlier in thread 1 I stated a better method would be to just make a cavity oscillator out of the whole thing.    It's a lot easier to make an RF circuit oscillate at the resonant frequency than it is to "lock" the frequency.    What does he mean by "lock" anyway?   And what kind of sensor tells him the generator is at the right frequency?    It really looks more like a cavity oscillator that is constrained to a narrow frequency band.    If the blocks labelled FGU were bandpass filters followed by amplifiers it would be a cavity oscillator.    That might be what he is doing but there is still nothing that explains how fundamental laws of physics are violated.
« Last Edit: 05/07/2015 10:35 PM by zen-in »

Offline deltaMass

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@frobnicat
Quote
Added emphasis. If it can be of any comfort to you, I understand both your arguments and humour (so far).
Gratifying because I'm sure many don't. We do seem to think along the same lines. On a practical note, I think the next step is to predict how best to distinguish the "trash Noether" or "trash Einstein" models. This comes down to doing what TheTraveller describes when comparing input and output power using some sort of rotary device. We will have a differential equation that includes velocity-dependent friction.  We will need to devise a good metric so as to be able to best differentiate between the two scenarios based on the Pout vs. Pin data. I am handwaving here because I have not yet drilled down on this.

Here in a nutshell are my "position papers"
http://forum.nasaspaceflight.com/index.php?topic=36313.msg1369875#msg1369875
http://forum.nasaspaceflight.com/index.php?topic=36313.msg1370943#msg1370943
« Last Edit: 05/07/2015 10:41 PM by deltaMass »

Offline WarpTech

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I know Shawyer and EW have tried a dielectric in the frustum. Are there any specifications for that dielectric? Material properties? Absorption properties at microwave frequencies?

I was looking at Pyramid Absorbers for microwaves, they can attenuate up to -55dB. A high power microwave source, pumped through a diode into such an absorber, seems to me should have a higher probability of thrust than the EM Drive and relatively simple to construct.


Todd D.

Offline PaulF

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I think that the solution is really simple, if it's about demonstrating a thrust effect that is many times larger than measurement precision: Crank up the RF power. A lot. There is really no two ways about it. Please don't even try to play with a power level that even a 9V-battery can put out.. . Personally, I'd play in a power regime of about 1kW (actually I do, but that's another story..) . 1KW is a level that can easily be handled by readily available parts and off-the-shelf electronics, but is still not excessive.

How about using Tesla batteries for a few seconds (>300 KW?) and send the damn thing at the other side of the galaxy? Would that form a convincing test result?
From what I distill from some of the information I have read, coronal discharges were already plaguing some of the teams at power between 100 and 1000 Watts. a 300KW burst would probably fry everything we can throw at it and would require serious re-design of the components and use of materials, if at all possible.
The problems with coronal discharges were with amplifiers. Magnetrons aren't affected by this, as they have no capacitors.
Tesla's batteries are unobtanium for the next year, it appears, so I am not even evaluating them at this stage.
Another way to get high power from a small battery pack is to use non-rechargeable liquid-electrolyte lithium batteries. They have a hell of a capacity per kilogram. Put a good few of those in series and parallel and you can probably power up to 2.5 kW for a short time. Disadvantage is that they are non-rechargeable and not exactly cheap.. But they could be useful for short duration high power tests to check linearity or whatever you science guys want for comparison with lower power tests.
« Last Edit: 05/07/2015 10:39 PM by PaulF »

Offline ThereIWas3

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Using low temps and low power is definitely the way to go during this "how does it work?" phase.  Much safer.  But keep your eyes away from it and have a microwave leak detector at hand.

The high-power engineering can be done after the basic principles involved are understood.
"If you want to build a ship, don’t drum up people to collect wood and don’t assign them tasks and work, but rather teach them to long for the endless immensity of the sea" - Antoine de Saint-Exupéry

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