Derek Sutherland

CSO @RealtaFusion | Advisor to @doescience (SCAC) | Science, engineering, space, energy, philosophy, music, art and coffee.

[Derek Sutherland @dasutherland]

@OverReactor1776 @MTSlive Of course. There’s no other way to do it right.

[Derek Sutherland @dasutherland]

@OverReactor1776 @MTSlive Absolutely. We should do a show on what energy abundance means and will look like once fully unlocked, bringing together heavy hitters from across the energy space.

[Derek Sutherland @dasutherland]

@atomicarchive They should have waited two more days to mark the anniversary of the Ivy Mike detonation! 10 MT on November 1, 1952.

[Derek Sutherland @dasutherland]

@bscholl Congrats @bscholl and team! Amazing progress. Firm power ftw!

[Derek Sutherland @dasutherland]

@Andercot In other words, everyone gangster until the Lundquist number gets high, pressure gradients get large, and vacuum vessel boundary conditions exist.

[Derek Sutherland @dasutherland]

@Andercot Definitely make sure there’s enough reality built in! It’s still humbling to see (repeatedly) how everything looks great on paper / in silico then you actually build it and have to deal with the final boss of reality. Has all the physics at full resolution all the time 🤦‍♂️

[David J. @TheDavid_Jay]

@CoraBuhlert Because the destruction of beauty by nihilistic brutes is something that should offend any civilized person, no matter where it occurs.

[Derek Sutherland @dasutherland]

@Gena_I_Gorlin Nice! Same color scheme and model. 😉 Enjoy FSD!

[Derek Sutherland @dasutherland]

@smartereveryday Best of luck on your defense! I’ve been reading Cassibry’s work for years and always appreciated the fusion propulsion concepts.

[Derek Sutherland @dasutherland]

@damienscott In mirrors we trust. 🫡

[Derek Sutherland @dasutherland]

One more click down in detail.

This difference in temperature is fundamentally because we’re pursuing a different type of fusion in machines on Earth than the Sun. The Sun uses the proton-proton fusion chain that even at solar densities has low power density (~275 W/m^3), but it’s made up for in a massive fusing volume that can be gravitationally confined at that scale.

On Earth, we’re using different fusion reactions that result in much higher power densities, order ~ MW/m^3 averaged over the machine volume. But, to reach these high fusion power densities, you need higher temperatures for the reactivity to be high enough (most commonly for deuterium-tritium, around 150 million degrees). This is set by the cross-sections for these reactions.

Because we can reach much higher fusion power densities than the Sun, we (fortunately) don’t need as large of a plasma volume to produce a significant amount of power. But since the mass of fuel is so much smaller in machines on Earth, we can’t use gravitational confinement since it’s such a weak force.

We need something stronger, which is typically electromagnetic (either pulsed lasers / magnetic fields for inertial confinement, or steady-state magnetic fields generated by electromagnets for magnetic confinement).

Net result we can generate many more watts per square meter in machines on Earth than gravitational confinement fusion with a 93 millions mile standoff (solar power). In applications where power density is important, high power density fusion is compelling (e.g. fusion propulsion with high thrust, specific power and impulse simultaneously.)

tl;dr we’re using different fusion reactions with higher power density on Earth that demands higher temperature. Since the fuel mass is so small and gravity is a weak force, gravitational confinement doesn’t work, and so the need to confine using magnetic / inertial schemes. The result is more watts per square meter, which means more power from a smaller physical footprint from fusion in machines on Earth even though the Sun generates a huge number of watts due to its massive volume.

At a 93 million mile standoff, we’re taking about at least a factor of a thousand higher power loading in fusion machines on earth (~ MW/m^2) than solar power (~kW/m^2), so a thousand times less area to generate the same amount of power. Power density is not the most important quantity for terrestrial power sources, but where it is more important high power density fusion looks compelling.

[World of Engineering @engineers_feed]

Fusion energy requires plasma hotter than the sun. 10× hotter than the sun's core.

The sun's core: ~15 million °C.
Fusion reactors need: 100–150 million °C.

Why? The sun uses gravity to compress plasma. We can't recreate gravity, so we compensate with temperature.

No material can contain plasma at 150 million °C.

So we don't use material. We use magnetic fields. That's what a tokamak is, a magnetic bottle.

The engineering challenge isn't getting it hot.
It's keeping it hot long enough to produce more energy than you put in.

[Derek Sutherland @dasutherland]

@XFreeze Argon is a lot cheaper than krypton (and xenon). Smart move.

[Derek Sutherland @dasutherland]

@PlatypusX9 I’m surprised they wanted to fly so badly without @Starlink.

[Derek Sutherland @dasutherland]

What about fusion drives for space propulsion? Seems like one of the “closest to ready” options for high specific power and ISP. More capable than NEP but easier to pull off than antimatter.

Getting to Mars faster and when you want to sounds compelling long term. Any other options?

[Derek Sutherland @dasutherland]

@jordanbramble @AntaresNuclear Congrats on the Space Force contract! Super exciting to see. We need more nuclear power in space.

[Derek Sutherland @dasutherland]

@WillManidis If they can orchestrate syndicates to insure large-scale nuclear power plants, I bet they can figure out something similar for AI.

[Derek Sutherland @dasutherland]

@prof_kamilov You forgot the part where they finally agree it’s correct once they determine it was their idea all along.

[Derek Sutherland @dasutherland]

@CatboyRocketry Unfortunate to hear. Maybe some longer form content on the topic would help start an actual discussion.

[Derek Sutherland @dasutherland]

I think the primary issue is people using their credentials as a means of arguing from a position of authority. The “I have a Ph.D and you do not, therefore I’m right” rather than the “here’s my argument supported by this evidence, let’s discuss and find the truth.”

In short, credentialism is bad, critical thinking is good. Don’t claim something is impossible unless it’s either self-evident or you do your own diligence.

Credentialism is often conflated with academia where it is prolific, but it’s also present in other sectors too. The “I was a leader in a fortune 500 company for 20 years, therefore I how to run a deep tech startup better than you.” Just because you succeed in one arena doesn’t mean those skills are fit for purpose elsewhere without some adaptation / revision.

We need to encourage evidence-based critical thinking across the board since that’s the only way to understand reality and what it can do. And that applies no matter where you’re working or what letters you may have after your name.

[Peter Hague @peterrhague]

Do you think academics in STEM departments don’t get questioned and challenged? That they don’t have to test their hypotheses against data?

People have a weird view of academia sometimes. Astrophysics isn’t a bunch of woke people sitting around chatting about stellar oppression.