Recommended Posts

4 minutes ago, kerbiloid said:

The higher is the temperature - the higher is noise. Not exactly the electronics meltdown, but just an electric and acoustic noise which can just make this electronics useless, while still solid. An overclocking inside out.

It isn't because the high temp meltdown of silicon carbide, but for the higher band gap, allowing more "noise" if I understand correctly, probably at a cost of higher consumption.

Example, (I have only read the abstract, I'm lazy today, I don't remember my original source) http://link.springer.com/referenceworkentry/10.1007%2F978-0-387-29185-7_24

It also cites the diamond as a high temp electronic material.

And I know there is high temp effects on materials, but then we already have materials withstanding this kind of conditions, lots of superalloys usually work in worse conditions. We can deal with that using more security margin or whatever, that's a design problem.

Share this post


Link to post
Share on other sites
13 minutes ago, kunok said:

I understand that the idea is that the band gap is bigger than the amplitude of the noise made by that effect, no? Some electronic engineer or solid state physic here?

Not sure what the necessary threshold is, but I know that band gaps only refer to gaps in energy states. Distributions within those two states is governed by boltzman equations, which are temperature dependent. As you ramp up temperature, you begin to populate the higher energy state more. In order to make use of that gap, you need a difference in population that can be exploited. If you populate the higher state too much, you end up with a negligible difference in populations, that means you have one state, and no band gap in the most extreme case. I believe it also plays into tunneling, which can be an issue for sophisticated circuits.

Share this post


Link to post
Share on other sites
5 hours ago, kerbiloid said:

I like the idea of monstrous coal-dark zeppelines silently barraging in a blurry sky of the Venus. :cool:
But fluorine plastics are still in order. Snow-white silently barraging zeppelins are nice, too.

Also I'm fond of steel-only electronics, with no solder, plastic, chips and so on. Good old dieselpunk automatons with honest gear-wheels ilogic nstead of pathetic microchips. :wink:

When the whole drilling machine is several dozen tons (?), its heat capacity would be overflown in several hours.
Any cooling system must evacuate the waste heat into outer world.

Not absolutely at all. The greater is wind speed - the greater are its local turbulences. So, the crew would still have green faces (not Kerbal) with popped out eyeballs (still not Kerbal, though looks similar) , just without expressed flow direction.

-270° cryogenic LH2 inside .500° atmosphere, with its extremely low density would mean ~800 K temperature difference between fiery hell and superfrosty hell, separated only with several centimeters of insulation.
The hydrogen would finish very quickly.

.To float up it should be either a rocket, or a balloon.
The first would return 1 kg of payload per 1 t jf the lander's mass. The second would melt before inflate.
Perhaps, combining the said lander and earthquaker into a big nuke solves all these problems. The cargo delivers itself, as a cloud.

This Russel's teapot should reach the near-Sun orbit in several minutes after its landing.

The hydrogen won't get stored at the surface, it's for rocket fuel. 

You can use copper for your electronics as well, but I'm imagining you won't have allot of circuitry. Just some hydrolic pumps to work the arms of the scooper. The smart section would be very small, and the first thing cooled by the flowing water.

The water reserve would be kept isolated as much as possible, some low pressure helium insulation should work pretty well. Once the reservoir of water starts getting too hot it can be vented at a higher rate to finish filling the piston and allow liftoff. But the system is designed to have the water reach boiling point, just in a controlled fashion.

Also, pretty sure pure graphene is colorless but I might be wrong about that.

Edited by todofwar

Share this post


Link to post
Share on other sites
4 hours ago, kunok said:

I understand that the idea is that the band gap is bigger than the amplitude of the noise made by that effect, no?

The greater is noise - the harder to select signal, the less is processing speed, the more additional hardware to keep signal/noise ratio meaningful.

4 hours ago, kunok said:

Some electronic engineer or solid state physic here?

Not electronic, not solid state.

3 hours ago, todofwar said:

You can use copper for your electronics as well, but I'm imagining you won't have allot of circuitry. Just some hydrolic pumps to work the arms of the scooper. The smart section would be very small, and the first thing cooled by the flowing water.

If you have either a great heat capacity, or white hot radiators and turbopumps for heat exchange.
The IRL industrial high-temperature hardware has both. On the Venus this is just a tiny platform surrounded by 500°C fluid with much greater heat capacity, To cool itself, it must have 1000°C hot radiators right on its surface, a reflecting insulation in between and a powerful pump system to take heat from inside and give it to that radiator. (And such pump needs much energy itself). So, unlikely such construction would last long.

3 hours ago, todofwar said:

Also, pretty sure pure graphene is colorless but I might be wrong about that.

I meant carbon plastic.

Spoiler

478px-W78_MK12A_RV_Minuteman_III.jpg

 

Share this post


Link to post
Share on other sites
17 hours ago, kunok said:

It isn't because the high temp meltdown of silicon carbide, but for the higher band gap, allowing more "noise" if I understand correctly, probably at a cost of higher consumption.

Semiconductors must have certain carrier densities. Electrons and holes. They are controlled by doping, strain, electric fields etc. However, they are strongly temperature dependent. At too high temperature too much electrons is excited from valence band to conduction band. These carriers cause conduction and transistors can not be shut down anymore which leads to fault action, more heating and destructive thermal runaway. On the other hand, if temperature is too low, doping atoms can not donate or accept electrons and semiconductor stays in insulating state.

There are some high temperature materials which have larger bandgap. For example silicon carbide which has been already mentioned. However, they are typically difficult to dope and process to components. Components need also insulators, package materials, metal bonds etc. They have different thermal properties and may lead to problems when temperature changes. As far as I know there are no stock electronics which can operate even nearly at the temperature of Venus surface.

Share this post


Link to post
Share on other sites
5 hours ago, Hannu2 said:

Semiconductors must have certain carrier densities. Electrons and holes. They are controlled by doping, strain, electric fields etc. However, they are strongly temperature dependent. At too high temperature too much electrons is excited from valence band to conduction band. These carriers cause conduction and transistors can not be shut down anymore which leads to fault action, more heating and destructive thermal runaway. On the other hand, if temperature is too low, doping atoms can not donate or accept electrons and semiconductor stays in insulating state.

There are some high temperature materials which have larger bandgap. For example silicon carbide which has been already mentioned. However, they are typically difficult to dope and process to components. Components need also insulators, package materials, metal bonds etc. They have different thermal properties and may lead to problems when temperature changes. As far as I know there are no stock electronics which can operate even nearly at the temperature of Venus surface.

All sounds like one of those things that may feedback into earth applicable systems. I'm sure there are places we'd like higher temp circuits, if the tech was available. 

Share this post


Link to post
Share on other sites

@Hannu2 @todofwar I think I found something https://smartech.gatech.edu/bitstream/handle/1853/26452/147-242-1-PB.pdf

Developments:
-Durable metal SiC contacts at 500ºC (page 15) and package (Al2Oencapsulate and gold contacs, page 17-19)
-JFET SiC transistor (page 16) tested during 4000hours at 500ºC (page 21) being stable and with a huge current ratio between on and of states allowing logic.
-And more complicated stuff like ¿wireless telemetry chips?, mems gas sensors, accelerometers, I'm sleepy, lazy and is not my field, seriously look

And this is from 2008. There is more here https://sic.grc.nasa.gov/. I will research more another day

Share this post


Link to post
Share on other sites
12 hours ago, todofwar said:

All sounds like one of those things that may feedback into earth applicable systems. I'm sure there are places we'd like higher temp circuits, if the tech was available. 

Certainly and that is why high gap semiconductors have been investigated. Higher operating temperature and ability to handle high voltages means smaller, cheaper, faster, more efficient and more reliable components in power electronics in industry and electricity networks. Venus probes will be extremely marginal application for high temperature electronics.

9 hours ago, kunok said:

Experimental stuff seems to have nice specifications. I made a short search for commercial components and they had much lower temperature limits. However, surface temperature is about 500C. There should be some room for heating. Energy production is also very hard. Atmosphere absorbs all short wavelength radiation from Sun which could be able to produce electricity in high gap solar cell. Any heat engine with low temperature at 500 C would be quite imaginative. I think that electronics would not be the hardest challenge in long period operation on Venus.

Share this post


Link to post
Share on other sites
4 hours ago, Hannu2 said:

Any heat engine with low temperature at 500 C would be quite imaginative.

Not at all, actually. Modern combined cycle gas turbines work with a heat rejection temperature from the topping cycle of over 500oC quite happily. Turbine inlet temperatures can now approach 1500oC, so your Carnot efficiency between your two thermal reservoirs is going to be about 56%. Practical efficiency is going to be closer to 35%, and you're going to have to bleed off quite a lot of power for active cooling of various systems, but thermodynamically the numbers add up just fine.

Share this post


Link to post
Share on other sites
5 hours ago, Hannu2 said:

Certainly and that is why high gap semiconductors have been investigated. Higher operating temperature and ability to handle high voltages means smaller, cheaper, faster, more efficient and more reliable components in power electronics in industry and electricity networks. Venus probes will be extremely marginal application for high temperature electronics.

Experimental stuff seems to have nice specifications. I made a short search for commercial components and they had much lower temperature limits. However, surface temperature is about 500C. There should be some room for heating. Energy production is also very hard. Atmosphere absorbs all short wavelength radiation from Sun which could be able to produce electricity in high gap solar cell. Any heat engine with low temperature at 500 C would be quite imaginative. I think that electronics would not be the hardest challenge in long period operation on Venus.

Don't forget wind power. It's slow, but steady and reliable and with higher mass than our own atmosphere.

Share this post


Link to post
Share on other sites
52 minutes ago, todofwar said:

Don't forget wind power. It's slow, but steady and reliable and with higher mass than our own atmosphere.

Power of a wind turbine is Eta*0.5*A*Rho*v3 where eta is the efficiency (maximum of 57%), A is the swept are, rho is the density, and v is the windspeed.

Density at the surface of Venus is 67 kg/m3, but wind speeds are quite slow, apparently around 3 m/s. A 1MW turbine would have to have a minimum area of 970m2. This corresponds to a rotor diameter of ~36 metres (compared to a 60m diameter for a similarly rated turbine on earth). A corresponding 1MW (~1500HP) gas turbine would be a lot more compact, if not a huge amount lighter.

Share this post


Link to post
Share on other sites

All i can think of is gathering stuff from the atmosphere, if it is possible.

Share this post


Link to post
Share on other sites
11 hours ago, peadar1987 said:

Power of a wind turbine is Eta*0.5*A*Rho*v3 where eta is the efficiency (maximum of 57%), A is the swept are, rho is the density, and v is the windspeed.

Density at the surface of Venus is 67 kg/m3, but wind speeds are quite slow, apparently around 3 m/s. A 1MW turbine would have to have a minimum area of 970m2. This corresponds to a rotor diameter of ~36 metres (compared to a 60m diameter for a similarly rated turbine on earth). A corresponding 1MW (~1500HP) gas turbine would be a lot more compact, if not a huge amount lighter.

It's not just about size and weight though, wind is a nice steady source of free energy. And if you use a kite, you can access much faster speeds not too high off the ground. 

Share this post


Link to post
Share on other sites
22 minutes ago, todofwar said:

It's not just about size and weight though, wind is a nice steady source of free energy. And if you use a kite, you can access much faster speeds not too high off the ground. 

It's definitely an option. Without running the numbers any further, I'd still say a nuclear-powered Brayton cycle would give you less headaches in the long run though.

Share this post


Link to post
Share on other sites

Mining of Venus should from its atmosphere, specifically carbon … a side benefit is supporting terraforming of the surface … imagine a "straw from geo" into the atmosphere

Share this post


Link to post
Share on other sites
On 10/16/2018 at 7:40 PM, Hobbs said:

Mining of Venus should from its atmosphere, specifically carbon … a side benefit is supporting terraforming of the surface … imagine a "straw from geo" into the atmosphere

Welcome to the forum!  

Electical generation on Venusian blimps has two possibilities: Solar Panels covered in FEP Teflon for protection against heat and acid, or wind power.  To generate wind power though, you would have to anchor the blimp to the ground, which would be hard in the acid, heat, and constant stress.  

Share this post


Link to post
Share on other sites
This thread is quite old. Please consider starting a new thread rather than reviving this one.

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.