Vacuum tubes for venus rover?

[coppercone2]

I suspect everything would be complicated. You need magnetic drive on all the wheels, teflon insulation, and all the magnets for motors would have to run at silly temperatures, or you need a very nice heat exchanger of some kind. Pure titanium radiator

If the magnets in the motor got hot, then you suddenly don't have much power.

I think it would have to be like a titanium tank thread.

Since it would probobly still run at a elevated temp, you lose tons of power in the motor from the magnetic isolation and the increased temperature. Then you need more magnets.


Even if you get tubes to run at ambient for the power supply, you still have magnets, unless it has something new, like high temperature piezo motor drive for the wheels. that might actually be a better idea, since it run at HV from tubes and does not have magnets. But it would still need a really good seal or magnetic isolators from the motor to the wheel, even if the motor does not have a magnet. Piezo motors are very sensitive to corrosion from what I have seen, it relys on uber flat contacts that are clean.


https://www.techbriefs.com/component/content/article/24957-npo-49735


I think even if you can get a piezo motor that runs at ambient, you would need a cooled magnetic coupler to transfer force from the hermetic motor. Neodymium totally fails at 300C. YOu have 450C ambient.


Unless you get a shaft seal to work at 500C for the motor in the corrosive enviroment. Then maybe its possible to have not cooled motors that actually let this thing move around at a 450c enviroment, if piezo still functions lol


But this requires a new material
"PI HVPZTs have a Curie temperature of 300°C and can be operated up to a max temperature of 150°C and some cases to 200°C (with high temperature option). In ..."

https://www.researchgate.net/publication/257953339_A_High-Temperature_Double-Mode_Piezoelectric_Ultrasonic_Linear_Motor

It sound like MAYBE we are almost at making a motor that works at that temp. But then there is the shaft seal. something from chemical plant maybe.



because cooling 1 nice camera is possible IMO, with a small titanium heat exchanger with some fancy compressor. the motors are a much much bigger problem. You can get CMOS in there with a 30 watt air conditioner I think. Impressive, but not nearly as impressive as what is required to cool the locomotion.


*****
Maybe it would be a new type of motor, like a phase change sprocket thing. you could arrange phase change actuators radially so they change the center of mass by moving a heavy piston forward to get something to rotate. Or a liquid metal hydraulic motor that uses a MHD  as a power source


there is this concept too, but I think its not a rover (sail boat)
https://en.wikipedia.org/wiki/Zephyr_(rover)

It needs a NAK hydraulic drive on titanium tank threads powered from its own nucular reactor

[T3sl4co1l]

Well, magnets are easy, SmCo have Tc > 700C and very similar properties to NdFeB; they're a common alternative, just more expensive, so tend to be used in more specialized applications where the more stable field or higher temperature limit is important.  Going even further back, Alnico could even be used -- high Tc, though a much lower energy product than these types so isn't very relevant today.  (There's maybe also PtCo, I guess if you needed the chemical resistance -- but more likely plating would afford that more easily.)

High temperatures increase metal resistance; copper at 300C is about as good as Al at RT, or a bit worse.  This wastes efficiency, but it does mean somewhat higher alloy fraction can be used, which may be important for maintaining strength at temperature.

Huh. There used to be a really convenient, always came up on obvious keywords, simple website that plotted resistance (or maybe it was conductance, or both) vs. temperature for several metals.  It doesn't seem to exist now -- or, Google has changed so much that it refuses to return the result.  Searching on archive.org sadly doesn't seem to show anything either.  One of you remember what I'm taking about, right?  Did anyone bookmark or download that page?

Tim

[coppercone2]

I see there is a new magnet that goes to 550C.

However, the wiring is going to be seriously dodgy at 450C. I wonder if a NAK hydraulic motor would be more efficient to transfer power then wires that are that hot. If the pump is right next to the power source it won't have too many losses. The liquid metal should stay liquid.

What do you even insulate it with? It would have to be like ceramic supported bus bars. Or I guess fiber glass jacketed without anything other then fiberglass (the technicians that build this will think its awful).

[coppercone2]

lol how do you wind the motor? wind it with fiber glass jacket magnet wire?

it sounds awful no matter which way you look at the motor. even if it was like micro drilled ceramic blocks that have wire threaded through it. It would have to be a big stack of really thin ceramic PCB for the winding with a ton of vias ? I have a feeling that will NOT be reliable at all

[coppercone2]

https://www.lpi.usra.edu/vexag/meetings/archive/vexag_4th/nov_2007/presentations/honeybee.pdf 

I think they wound it in fiberglass jacket on the core lol

https://esmats.eu/esmatspapers/pastpapers/pdfs/2017/rehnmark.pdf


and here is a tip for the guys there, use rodico to get magnetic dust off magnets. not tape.


so the magnet wire is covered by enamel and sintered together. i guess thats not that bad

[3roomlab]

i remember this SMD vac tube

https://www.korgnutube.com/en

korg seems to be all over it
it even has a SPICE model file

i dont think it would survive 10G
It was developed by Korg and Noritake Itron, the VFD guys
buy hey ! made in japan ! 30000 spec hrs !

[tggzzz]

There are many other devices possible. One is the nanoscale vacuum channel transistor (NVCT).

"Unoptimized initial NVCT devices show a potential of 0.5 THz operation. Exposure to radiations at doses typically experienced by space missions (a few tens of MRad gamma radiation and 10 MeV fast neutrons) showed negligible impact on device characteristics." https://science.nasa.gov/science-research/science-enabling-technology/nanoscale-vacuum-electronics-back-to-the-future/

Early days, but there are quite a few papers on such devices.

[coppercone2]

i remember this SMD vac tube

https://www.korgnutube.com/en

korg seems to be all over it
it even has a SPICE model file

i dont think it would survive 10G
It was developed by Korg and Noritake Itron, the VFD guys
buy hey ! made in japan ! 30000 spec hrs !

where do you get this

[coppercone2]

can't believe I bought one. I wonder what a good circuit would be for it.