Successful Nuclear Fusion Test at LLNL

[jvett77]

The recent successful fusion experiment at Lawrence Livermore National Labs created a positive energy gain of 150%, a first for any fusion reactor. Even though the NIF reactor actually lost 99% of its 400 megajoules input energy delivering 2 MJ of laser energy to the target fuel pellet, it nonetheless achieved its fusion threshold goal by producing 3 MJ and it is in fact a scientific breakthrough. The reaction took place in less than a microsecond. (a MJ is less than 1/3 of a kwh).

This was a miniscule step in this process that will take more than several decades to a century before a workable fusion reactor can be connected to the power grid supplying electricity to our homes. Here's a summary of problems to be overcome for this type of reactor:

1. "The NIF is built on 1980s laser technology,” said Kim Budil, director of the Lawrence Livermore National Laboratory, "the lasers are only 1 percent efficient in terms of turning electricity to laser light, while more modern designs can be 20 percent efficient."

2. The NIF reactor generates bursts of energy by quickly burning one tiny chunk of fuel after another. Scientists have yet to figure out how to replace the fuel pellets quickly enough to maintain a reaction for longer than the tiniest fraction of a second. Making it happen 10,000 times faster is absurdly difficult.

3.The NIF takes hours to recover from each experiment. The fact that NIF is able to do this once per day is a technical achievement that took years to perfect. NIF can only fire a few laser shots per day. To run an actual fusion reactor, you’d need to fire about 10 shots per second.

4. There is a dwindling supply of tritium, a key isotope that is combined with deuterium as fuel for the reaction.

5. The huge technical problem is maintaining a mass of plasma at a temperature of several million degrees to enable fusion, while extracting enough heat to provide useful energy.

There is no "breakthrough": NIF fusion power still consumes 130 times more energy than it creates

 

[jvett77]

In exploring fusion research, the non-radioactive isotope, Helium-3, would be an ideal fuel for the operation of a fusion reactor; it consists of fusing helium‑3 with deuterium, rather than hydrogen isotopes deuterium and tritium used in the recent NIF test.

Getting large quantities of H3 is the problem. One scientist estimated that United States crustal natural gas sources may have only half a ton total. Then perhaps another 1,200 tons in interplanetary dust particles on the ocean floors. In a 1994 study, extracting helium-3 from these sources would consume more energy than fusion would release.

Unlike Earth, which is protected by its magnetic field, the Moon has been bombarded with large quantities of Helium-3 by the solar wind. Because of the low concentrations of helium-3, any mining equipment would need to process extremely large amounts of lunar crust, regolith, 150 tons to obtain one gram of helium-3.

Estimates say that the Moon's surface contains helium-3 at concentrations between 1.4 and 15 parts per billion in sunlit areas and as much as 50 ppb in shadowed regions. For comparison, helium-3 in the Earth's atmosphere occurs at 7.2 parts per trillion.

One optimistic article stated roughly 1.1 million metric tons of the H3 isotope exists on the Moon down to a depth of several meters. Twenty-five metric tons of helium-3, about a quarter of the cargo capacity of a SpaceX Starship, would suffice to fuel all the power needs of the United States for a year.

The Chinese Lunar Exploration Program is investigating lunar mining, specifically looking for the isotope helium-3 for use as an energy source on Earth. These efforts will be interesting over the next few decades but don't seem realistic right now. “The joke in fusion is that it’s been 30 years away for 50 years.”

02/28/21
Solving the climate and energy crises: Mine the Moon’s helium-3?
Helium-3 - Wikipedia