Laser-heated nanowires produce micro-scale nuclear fusion

The target chamber (front) and ultra-high density laser (back) used in the micro-scale fusion experiments at CSU. Credit: Advanced Beam Laboratory

Nuclear fusion, the process that powers our sun, happens when nuclear reactions between light elements produce heavier ones. It's also happening at a smaller scale – in a Colorado State University laboratory.

Using a compact but powerful laser to heat arrays of ordered nanowires, Colorado State University (CSU) scientists and collaborators have this month demonstrated micro-scale nuclear fusion in the lab. They have achieved record-setting efficiency for the generation of neutrons – chargeless sub-atomic particles resulting from the fusion process. Their work is detailed in a paper published in Nature Communications, and is led by Jorge Rocca, University Distinguished Professor in electrical and computer engineering and physics.

Laser-driven controlled fusion experiments are typically done with multi-hundred-million-dollar lasers housed in stadium-sized buildings. Such experiments are usually geared toward harnessing fusion for clean energy applications. In contrast, Rocca's team worked with an ultra-fast, high-powered, tabletop laser they built from scratch.

The CSU team used their fast, pulsed laser to irradiate a target of nanowires and instantly create extremely hot, dense plasmas – with conditions approaching those inside the sun. These plasmas were seen to drive fusion reactions, giving off helium and flashes of energetic neutrons.

In their experiment, the team produced a record number of neutrons per unit of laser energy – about 500 times better than experiments that use conventional flat targets from the same material. Their laser's target was made of deuterated polyethylene. This material is similar to the widely-used polyethylene plastic – but its common hydrogen atoms are substituted by deuterium, a heavier kind of hydrogen atom.

These efforts were supported by intensive computer simulations conducted at the University of Dusseldorf (Germany), as well as CSU.

Making fusion neutrons efficiently, at a small scale, could lead to advances in neutron-based imaging, and neutron probes to gain insight into the structure and properties of materials. The results also contribute to understanding interactions of ultra-intense laser light with matter.

The paper is titled "Micro-scale fusion in dense relativistic nanowire array plasmas." The research was supported by the Air Force Office of Scientific Research and by Mission Support Test Services, LLC.

Top left: A scanning electron microscope image of aligned deuterated polyethylene nanowires. The other panels are 3-D simulations of the nanowires rapidly exploding following irradiation by the ultra-intense laser pulse. Credit: Advanced Beam Laboratory Source: n
Read More........

IBM developing world's smallest computer

Credit: IBM Research
Most people are familiar with Moore's Law, but few have heard of Bell's Law – a related phenomenon coined by U.S. engineer Gordon Bell. This describes how a new class of computing devices tends to emerge about every decade or so, each 100 times smaller than the last. The shrinking volume of machines becomes obvious when you look back at the history of technology.

The 1960s, for example, were characterised by large mainframes that often filled entire rooms. The 1970s saw the adoption of "minicomputers" that were cheaper and smaller. Personal computing emerged in the early 1980s and laptops became popular in the 1990s. This was followed by mobile phones from the 2000s onwards, which themselves became ever thinner and more compact with each passing year, along with tablets and e-readers. More recently there has been rapid growth in wireless sensor networks that is giving birth to the Internet of Things (IoT).

The new computer announced by IBM is just 1mm x 1mm across, making it the smallest machine of its kind to ever be developed. It will feature as many as a million transistors, a solar cell and communications module. The company predicts these devices will be in widespread use within five years, embedded in all manner of everyday objects. So-called "cryptographic anchors" and blockchain technology will ensure a product's authenticity – from its point of origin to the hands of the customer. These high-tech, miniature watermarks will (for example) verify that products have originated from the factory the distributor claims they are from, and are not counterfeits mixed in with genuine items.

In some countries, nearly 70 percent of certain life-saving pharmaceuticals are counterfeit and the overall cost of fraud to the global economy is more than $600bn every year. This new generation of tiny computers will monitor, analyse, communicate and even act on data.

"These [crypto-anchor] technologies pave the way for new solutions that tackle food safety, authenticity of manufactured components, genetically modified products, identification of counterfeit objects and provenance of luxury goods," says IBM research chief, Arvind Krishna.

Looking further into the future – if Bell's Law continues – devices are likely to be small enough to fit inside blood cells within a few decades. The potential applications then will become like science fiction: could we see a merger between humans and machines?

Read More........