China Claims Successful Fusion Power Test

SeaDour writes, "China claims to have carried out a successful test of its experimental thermonuclear fusion reactor. But what exactly made this test 'successful' is not clear. From the article: 'Xinhua cited the scientists as saying that deuterium and tritium atoms had been fused together at a temperature of 100 million degrees Celsius for nearly three seconds. The report did not specify whether the device... had succeeded at producing more energy than it consumed, the main obstacle to making fusion commercially viable.'" China is a participant in the 10-nation ITER project to build a fusion reactor in the south of France by 2015. The article quotes the research head of ITER as saying, "It was important for China to show that it is part of the club. Here are English language versions of the Chinese news release: announcement, background.

Re:Oh...

[RsG]

Nah, you want it to get as hot as possible. Higher temperature leads to more reactions in the fuel, which in turn leads to greater effeciency. Part of the problem is getting the fuel that hot in the first place, and keeping it together long enough to fuse.

Side note: while 100 million degrees sounds awfully hot, we're talking about a tiny amount of fuel here. The usual figure quoted for a hypothetical commercial reactor is about two grams of fuel in the core at any given time. The reactor itself doesn't get anywhere near that hot, even in the event of a full loss of containment.

I'm pretty sure it didn't hit Q=1

[spike hay]

It was successful in that it fused deuterium and tritium. Of course, the break even point doesn't matter. To be economical, the reactor realistically has to hit ignition, which only the ITER could hope to do.

Net gain not the obstacle!

[The_Wilschon]

Achieving a net energy gain is not the main obstacle to making fusion commercially viable. That has been done quite successfully. There is no problem passing break-even. It is ignition we are trying to achieve now. That is, a fusion reaction which produces enough heat to cause more fusion, provided enough fuel. If you're going to write an article about fusion, at least know something about the state of the field. Journalists should all be required to read the relevant wikipedia [wikipedia.org] articles before publishing something about science.

Re:Containment?

[spike hay]

Magnetic containment. This isn't like fission reactions. There isn't a "pile." Just a couple of grams of non-radioactive deuterium and radioactive but fairly benign tritium. In the event that the magnets somehow fail, the reaction will stop, with just a bit of erosion on the sides of the reactor.

Re:Containment?

[LotsOfPhil]

It's a superconducting tokamak. [wikipedia.org]
The new part is the fact that it uses superconducting magnets. Tokamaks have been used since the 70's.

Re:more energy than it consumed

[$RANDOMLUSER]

But that is the law of physics. The extra energy comes from the mass which is converted to energy. Had it said "producing more mass/energy than it consumed", then that would be against the laws of physics.

A Small Step

[quanminoan]

A fusion reactor has so many challenges behind it that ignition is only a small step towards something useful. Assuming you ignite a plasma you then have to maintain it, keep it stable, and fuel it fast enough to keep it burning. After that you're left with "mere" engineering problems, such as removing ~ 1 MW of heat per m^2 on the walls of the tokomak, making a gun fire a pellet of solid hydrogen into the plasma at one pellet per second, and finally creating a structure that can handle the intense neutron flux so the reactor can survive long enough to break even.

Though ITER is being built soon, it's being designed as its going up. I'm involved with creating an H- ion beam to inject the plasma (called neutral beam injection). The idea is to fire a high energy beam of neutral hydrogen into the plasma to heat it up (neutral so the atoms can travel through the containment magnets without deflection).

So even if the Chinese managed to build a reactor that beats previous records, it's a long while before fusion powers your home. Nevertheless I consider Fusion research to be one of the most important fields; it takes no imagination to understand what it would mean if nations could be powered on water.

Re:more energy than it consumed

[RsG]

Actually, you don't lose mass when you burn something. Chemical combustion converts potential chemical energy into heat, but the end products mass as much as the starting ones. All the energy in a gallon of gas is the energy that went into producing it.

But technically yes, when you talk about fusion reactors you should say "converted more energy from mass than it took to fuse said mass". So the phrasing from the article/summary is technically in error, but most people who know their physics can grasp what they actually mean.

Re:more energy than it consumed

[pclminion]

Actually, you don't lose mass when you burn something. Chemical combustion converts potential chemical energy into heat, but the end products mass as much as the starting ones.

Actually, you always lose relativistic mass when you release potential energy. A gallon of gasoline is more massive than the sum of the masses of its individual atoms (but not by much), due to the electromagnetic potential energy of the chemical bonds. By general relativity, any place in space with a nonzero mass or energy density is warped. Thus, the potential energy (think of it as being contained in the electromagnetic field between the atoms) actually contributes slightly to the effective mass of the system.

The fraction of relativistic mass lost when you burn a gallon of gas is probably so small as to be unmeasurable by any known measurement device, but it's there (at least if GR is correct).

Re:I'm pretty sure it didn't hit Q=1

[kidtexas]

Actually, it was successful in getting plasma, usually called "first plasma" in the field. I had heard it was 200kA for 1.2 seconds. I'm would be shocked if they actually were using tritium in the system at this early stage, but I could be wrong. I'm betting that was the result of the scientist media interface.

ITER, which is designed for a Q of 5-10 I think and most definitely for DT plasmas, is supposed to reach first plasma in 2016. I think the first DT plasmas for ITER are scheduled for 2019. The other 2 tokamaks that I know of that have done DT experiments (TFTR and JET) took quite a while before they started using tritium in the system as well. Which is why I'd be very surprised if EAST was trying DT plasmas from the get go. Getting a plasma at all with a measurable plasma current is enough.

Most hefty fusion research devices have fusion events. That in and of itself is not that ground breaking. There is a big difference between having fusion events and achieving break even though.

EAST is a big deal because it is all super conducting and I believe designed and made entirely in China (for less than $50 million from what I heard). I would imagine it's going to be quite an amazing machine, but as far as I know, it is meant to play a support role for ITER, not to beat it to the punch.

Re:A Small Step

[DragonWriter]

Yes, they'd start fighting wars over access to water instead of oil.

Water (both freshwater for agriculture, drinking, etc. and access to navigable water for trade) has been a vital resource over which wars are fought longer than oil (and, like oil, its been a big factor motivating or complicating Middle East conflicts, including providing a significant part of the motivation for Iraq's wars with Iran and Kuwait, and a complicating factor in resolving the Israel/Palestine problem.)

Re:Net gain not the obstacle!

[The_Wilschon]

Go out and get yourself a copy of An Introduction to The Physics of Nuclei and Particles by Richard A. Dunlap, first edition, published in 2004. This is one of the standard texts for an undergraduate physics course in nuclear and particle physics. See pages 192 and 193, esp. Figures 13.12 and 13.13. Then read the text on page 192. I will reproduce it here for your benefit:

In Figure 13.12 the broken line represents unthermalized breakeven. This refers to the situation where the energy output of the reactor is equal to the energy input but the plasma conditions have been augmented by neutral beam injection. The solid line represents thermalized breakeven where the plasma conditions themselves are sufficient for net energy production. The shaded region represents ignition where the energy output is not only sufficient to yield a net energy gain but is also sufficient to maintain the plasma conditions. This is a self-sustained fusion reaction. These operating conditions refer to d-t fusion; conditions for d-d fusion would follow curves with values of n\tau about two orders of magnitude larger. The data points in the figure represent the operating conditions of a number of experimental magnetic confinement reactors. The general trend of the points from the lower left to the upper right of the figure represents the chronological development of fusion reactors from the late 1960s to the late 1990s. This line also represents an increase in reactor power from the mW range to several MW. Present results are in the breakeven region and future developments can hope to achieve ignition. The time scale for such developments is presumably in the order of several decades.

The figure shows 2 points inside the solid line, and 15 points between the solid line and the broken line. Figure 13.13 on the facing page is a similar plot, showing inertial confinement experiments rather than magnetic confinement. However, 13.13 lacks the lines showing the two breakeven points.

Allow me to repeat the particularly relevant phrases (emphasis mine):

The shaded region represents ignition where the energy output is not only sufficient to yield a net energy gain but is also sufficient to maintain plasma conditions. This is a self-sustained fusion reaction.

Present results are in the breakeven region and future developments can hope to achieve ignition.

Direct from a credible source. Now, perhaps Dunlap is wrong. Credible sources have been quite wrong in the past and will be in the future. However, you'd best have a stronger argument than "no you're a poopyhead" if you expect anyone to believe you.

Re:Here's an additional press release, more info

[dan828]

Well, the "Me so horny" prostitute was Vietnamese (from the movie Full Metal Jacket), and it's the Japanese that have problems pronouncing Ls, not the Chinese. So, besides mixing up three different asian countries with distinct languages and cultures, your ethnic insult was spot on. Way to go!

Re:Net gain not the obstacle!

[deglr6328]

I believe the GP is right. No one has actually achieved breakeven (except for Dr. Edward Teller in the 50's but those weren't exactly practical power producing devices since they tended to obliterate everything in a 20 mile radius!!). The JET in Culham UK came closest a few years back at ~70% breakeven with a 50/50 DT plasma. Those dots you are seeing on that plot are almost certainly extrapolated breakeven points. meaning they represent the DD reactions done on the Japanese JT-60 device which WOULD, if done with a DT plasma, have achieved breakeven at 125% gain. But since they have never gone to DT plasmas on that device, because they don't have the facilities to handle T, they have not strictly broken even. The first thermonuclear device to break even in the laboratory will be the national ignition facility at LLNL when it is completed in 3 years.

Re:Oh...

[budgenator]

That's actually one of the main engineering problems, it's as lot easier to turn some fuel into a simulated sun than than it is to poke some fresh fuel into the middle of one.

Re:A Small Step

[quanminoan]

I hope you're all being sarcastic about water wars erupting if fusion succeeds, but if not here's a quote:

"Deuterium is abundant in ocean water, and one cubic kilometer of seawater could, in principle, supply all the world's energy needs for several hundred years." - According to an article in IEEE [ieee.org]

Add to this the fact that it's proposed Lithium be used to adsorb the neutron radiation from a reactor, which would in turn breed Tritium for use in the fusion reaction.

Re:Everyone will be doing it soon...

[sankyuu]

Word is that Dr. Farnsworth [wikipedia.org] of Futurama was actually named after the Dr. Farnsworth [wikipedia.org] who invented the CRT TV and the Fusor reactor.