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Category: energy – Page 2

Long-pulse fast ignition in magnetized liner inertial fusion

The fast-ignition paradigm for inertial confinement fusion allows for extremely high gains but requires fuel to be heated very quickly to outpace hotspot disassembly and energy losses. This demands lasers with high power and intensity, posing engineering challenges that have called into question the fundamental practicality of fast ignition. Magnetized liner inertial fusion (MagLIF) circumvents these problems through its large-aspect-ratio cylindrical geometry and strong axial magnetic fields that allow for ignition at lower areal densities. Furthermore, MagLIF’s large aspect ratio and higher yields relax other constraints on energy deposition and repetition rate, while its axial magnetic fields can be used to collimate ignitor electrons and thereby increase allowed standoff distance and save on ignitor energy. This tremendous overall relaxation of the engineering constraints that have historically limited the practicality of fast ignition suggests that the paradigm may be considerably more viable in a MagLIF context.

Sunlight-powered setup generates quantum entanglement

Today’s quantum technologies rely on energy-intensive lasers, raising concerns that scaling them up could further increase energy demands. In new work, researchers have demonstrated that quantum entanglement between photons can be generated directly from sunlight, offering a potential alternative.

“Quantum entanglement is crucial for applications such as secure communication, ultra-precise sensing and high-performance computation,” said Cheng Li, a recent graduate of the University of Ottawa in Canada. “Our work shows that abundant natural light sources can be used for quantum entanglement, opening the possibility of more energy-efficient and accessible quantum technologies.”

In Optica, the researchers report that the entanglement they achieved using sunlight was comparable to laser-based approaches after accounting for differences in the bandwidth of the input light.

Two decades of blazar observations, and the mysteries keep piling up

Narrow jets of luminous matter may be emitted toward Earth from the nuclei of active galaxies billions of light-years away. The galaxy then appears as a point source and is called a blazar. A Polish-German team of scientists has, for the first time, analyzed the activity of one such blazar over an extended period and, instead of finding answers, encountered an ever-increasing number of intriguing questions.

Distant, active galaxies that emit jets of matter at small angles toward Earth, known as blazars, present astronomers with numerous observational and interpretative challenges. Their immense distance and specific orientation, combined with the high variability of the emitted radiation—which, moreover, is generated across a very wide energy range—are the main reasons why understanding the phenomena responsible for the properties of blazars is particularly difficult.

Are the current interpretations of the nature of these objects, based on short-term and rather sporadic observations, correct? A group of scientists from the University of Heidelberg and the Institute of Nuclear Physics of the Polish Academy of Sciences (IFJ PAN) in Krakow set out to answer this question. The research carried out on the Polish side focused on the blazar PKS 2155-304, located one and a half billion light-years away. It is situated in the southern celestial hemisphere, in the background of the constellation Piscis Austrinus. The paper is published in the Journal of High Energy Astrophysics.

Scientists created the world’s whitest paint that reflects 98.1% of sunlight and it could cool buildings without air conditioning

Keeping buildings cool has become an increasingly difficult challenge as temperatures rise and air conditioning demand continues to grow. While cooling systems provide comfort, they also consume large amounts of electricity, adding to energy costs and greenhouse gas emissions.

How to keep the Earth habitable when the sun dies

In a billion years, the sun will start to run out of fuel and expand to become a red giant. Earth’s oceans and atmosphere will be burned away, and Earth will likely be engulfed by the sun altogether. The sun will then shrink to a dim white dwarf, and all light and warmth in the solar system will diminish. In a hundred trillion years, the galaxy’s ability to produce stars will be exhausted, and everything will turn dark. However, there’s a way for life to escape this fate—and what’s more, we wouldn’t need to leave the planet to do it. We just need to build some safeguards.

First problem—the sun. To block it out, we can place a large sunshade at the Lagrange point 1 (a gravitational balancing spot between the sun and Earth). We’d need to cover a huge 70-degree area of the sky to ensure the red giant would be eclipsed.

To reduce the required area of our sunshade, we can place a weight at Lagrange point 1, attach a long cable and place the shade close to Earth, just outside the moon’s orbit. We could mine 40% of the dwarf planet Ceres to produce a carbon tether 2 million km (1.2 million miles) long, and 0.01% of the moon to produce an aluminum sunshade 350,000 km (217,000 miles) in radius.

Catching and Guiding an Elastic Rainbow

Two experiments demonstrate a promising platform for trapping, sorting, and directing vibrational energy.

In a rainbow, sunlight separates into colors because each wavelength of light follows a different path. This familiar image has inspired an analogous idea in wave physics: A designed material can slow down different frequency components of a broadband signal at different positions, thereby sorting the signal in space. This concept, known as rainbow trapping, was introduced as a route to storing light in metamaterials [1] and has since motivated efforts to control sound, vibration, and other classical waves. But rainbow trapping has been difficult to realize for elastic waves—vibrations that temporarily deform a material as they move through it. Many rainbow designs have relied on vibrational modes confined to a sample’s edges or interfaces, limiting the available trapping area, or have lacked a way to access and route energy once it has been localized.

Now two teams have taken complementary steps toward overcoming these limitations. Yafeng Chen at Tongji University in China and colleagues have created and directly visualized an elastic rainbow in which different megahertz-frequency vibrations stop at different positions [2]. Meanwhile, Riyi Zheng at the South China University of Technology and colleagues have shown that a similar rainbow can be captured and redirected using topological edge states [3]. Together, these two studies transform elastic rainbow trapping into a platform for sorting, confining, and guiding vibrational energy.

Prototype glasses can turn infrared into color vision

The human eye, as good as it is, misses out on so much of the world because it is limited in what it can perceive. It can’t see X-rays, ultraviolet rays or infrared light. While X-ray goggles are still the stuff of science fiction, we may be moving closer to wearable glasses that make infrared light look almost like everyday vision. Scientists at the Beijing Institute of Technology have developed a device that transforms infrared light into a full-color visible image.

Human eyes cannot see infrared because infrared photons don’t have enough energy to trigger our retinas. Night-vision goggles and thermal cameras help, but they tend to show the world in one color, usually grainy green or black-and-white.

What this team has done is develop a technology that converts invisible infrared into multiple colors based on its wavelength and intensity. And because the eye is good at telling colors apart, the new technology allows people to distinguish subtle differences in infrared light much more easily than with traditional night-vision goggles. The researchers describe their work in a paper published in Science Advances.

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