Saturday, August 10th, 2024

Time	Event
3:30a	Mayonnaise Could Help Improve Fusion Energy Yields An anonymous reader quotes a report from Ars Technica: Inertial confinement fusion is one method for generating energy through nuclear fusion, albeit one plagued by all manner of scientific challenges (although progress is being made). Researchers at LeHigh University are attempting to overcome one specific bugbear with this approach by conducting experiments with mayonnaise placed in a rotating figure-eight contraption. They described their most recent findings in a new paper published in the journal Physical Review E with an eye toward increasing energy yields from fusion. The work builds on prior research in the LeHigh laboratory of mechanical engineer Arindam Banerjee, who focuses on investigating the dynamics of fluids and other materials in response to extremely high acceleration and centrifugal force. In this case, his team was exploring what's known as the "instability threshold" of elastic/plastic materials. Scientists have debated whether this comes about because of initial conditions, or whether it's the result of "more local catastrophic processes," according to Banerjee. The question is relevant to a variety of fields, including geophysics, astrophysics, explosive welding, and yes, inertial confinement fusion. [...] The problem is that hydrodynamic instabilities tend to form in the plasma state -- Banerjee likens it to "two materials [that] penetrate one another like fingers" in the presence of gravity or any accelerating field -- which in turn reduces energy yields. The technical term is a Rayleigh-Taylor instability, which occurs between two materials of different densities, where the density and pressure gradients move in opposite directions. Mayonnaise turns out to be an excellent analog for investigating this instability in accelerated solids, with no need for a lab setup with high temperature and pressure conditions, because it's a non-Newtonian fluid. "We use mayonnaise because it behaves like a solid, but when subjected to a pressure gradient, it starts to flow," said Banerjee. "As with a traditional molten metal, if you put a stress on mayonnaise, it will start to deform, but if you remove the stress, it goes back to its original shape. So there's an elastic phase followed by a stable plastic phase. The next phase is when it starts flowing, and that's where the instability kicks in." In 2019, Banerjee's team conducted experiments that "involved pouring Hellman's Real Mayonnaise [...] into a Plexiglass container and then creating wavelike perturbations in the mayo," writes Ars' Jennifer Ouellette. "One experiment involved placing the container on a rotating wheel in the shape of a figure eight and tracking the material with a high-speed camera, using an image processing algorithm to analyze the footage. Their results supported the claim that the instability threshold is dependent on initial conditions, namely amplitude and wavelength." "This latest paper sheds more light on the structural integrity of fusion capsules used in inertial confinement fusion, taking a closer look at the material properties, the amplitude and wavelength conditions, and the acceleration rate of such materials as they hit the Rayleigh-Taylor instability threshold." Read more of this story at Slashdot. (Comment on this)
7:00a	DARPA Wants To Bypass the Thermal Middleman In Nuclear Power Systems The Defense Advanced Research Projects Agency (DARPA) is exploring the possibility of directly converting radiation from nuclear reactors into electricity using radiovoltaics, a technology that could potentially revolutionize nuclear power generation by moving beyond traditional steam turbine methods. The agency is requesting information and suggestions on this topic in an RFI released on August 1st. Nuclear News reports: There's got to be a better way": Methods to convert the energy of nuclear fission reactions and the decay of radioisotopes into electricity have not evolved since the invention of radioisotope power systems and fission reactors over 70 years ago and remain unoptimized," the RFI says. They rely on thermal heat transfer, and "in each step of this indirect conversion method neutrons, heat, and energy are lost to the shielding material, working fluid, and other system materials." Advanced reactor designs that use alternative coolants, including helium, sodium, and salts, would still use what DARPA calls "heritage nuclear power conversion technology" with water and steam as the working fluids, as would the fusion power plants being planned today. Why now? Tabitha Dodson, the program manager for DARPA DSO, which is launching the RFI, told Nuclear News that "two big things" are driving the interest. "One is the extreme surge of investment in small and advanced nuclear technologies, such as in fusion and space reactors, which do not have a concurrent pairing of advanced power generation methods that doesn't involve liquid-based heat transfer," she said. "Next, there has been an order of magnitude improvement in radiation tolerance and efficiency for voltaics in recent years with encouraging performance that indicates radiovoltaics could scale up as an array usable in nuclear reactors." [...] What is the ask?: The RFI asks: "Is it possible to achieve [a] direct energy conversion nuclear power system, ranging in power from 10s of watts electric (We) to 100s of kWe?" DARPA wants information "on the potential to improve specific power greater than 1 We/kg conversion from watts-thermal per radiation emission product," and information on the potential to improve damage tolerance of the voltaic to nuclear radiation to reach an operating lifetime comparable to the life of its nuclear source, on the scale of decades. "We will learn what our boundary conditions are when respondents tell us what technologies in the field of voltaics are possible, and we'll use that to see if there is sufficient scientific rationale make a case to present for further DARPA investment," Dodson said. "I also hope people are going to start thinking about nuclear systems that use electromagnetic versus thermal-kinetic methods to harvest nuclear energetic reactions." Read more of this story at Slashdot. (Comment on this)
8:46p	Samsung's New EV Battery Tech: 600-Mile Ranges, and 9-Minute Charges? "Samsung's latest solid-state battery technology will power up premium EVs first, giving them up to 621 miles of range," writes PC Magazine: The new batteries — which promise to improve vehicle range, decrease charging times, and eliminate risk of battery fires — could go into mass production as soon as 2027. Multiple automakers have been reportedly testing samples. Samsung did not list any by name but it's worked with Hyundai, Stellantis, and General Motors, among others. "We supplied samples to customers from the end of last year to the beginning of this year and are receiving positive feedback," Samsung SDI VP Koh Joo-young said at SNE Battery Day 2024 in Seoul, according to Korean outlet The Elec and translated by Google. Perhaps unsurprisingly, the batteries won't be cheap. They will initially go in "super premium EVs" and will offer 900 to 1,000 kilometers (559-621 miles) of range and improved safety... Samsung's presentation also reiterated previously announced plans to create batteries that can charge in nine minutes and last 20 years by 2029. More details from Notebookcheck: According to Samsung SDI's VP, automakers are interested in its solid-state battery packs because they are smaller, lighter, and much safer than what's in current electric cars. Apparently, they are also rather expensive to produce, since it warns that they will first go into the "super premium" EV segment. Those Samsung defines as luxury electric cars that can cover more than 600 miles on a charge. Samsung's oxide solid-state battery technology is rated for an energy density of about 500 Wh/kg, which is about double the density of mainstream EV batteries. Those have capacities that already allow more than 300 miles on a charge, so 600 miles of range in a similar footprint is not out of the question, but the issue is production costs. Thanks to Slashdot reader npetrov for sharing the news. Read more of this story at Slashdot. (Comment on this)

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