Tag: electrons

Scientists may have solved a key barrier to fusion power

We’ve been working towards nuclear fusion, a near-limitless source of clean energy, for the past six decades, and now scientists have made a major breakthrough. A new article published in Physical Review Letters details how to solve a dangerous issue with runaway electrons that has, until now, posed a major problem for fusion reactors. Fusion reactors model themselves on the reactions that power our stars: Hydrogen atoms collide at such incredibly high speeds that they fuse into helium. That process releases astounding amounts of energy. It’s the same thing that’s happening in our sun’s core right now. Runaway electrons are simply free-floating electrons that are energized by potent electric fields. In the high energy of nuclear fusion, the levels and speeds to which these runaway electrons are charged can be catastrophic. The team discovered that it’s possible to decelerate the electrons by injecting heavy ions, like neon or argon, into the reactor. The electrons collide with these neutral atoms, resulting in energy loss and slower speeds. It may seem like a small step, but every problem we solve with nuclear fusion moves us closer to finally achieving it here on Earth. Linnea Hesslow, coauthor of the article, told Wired , “Many believe it will work, but it’s easier to travel to Mars than it is to achieve fusion.” We’ve got a long way to go yet, but eventually (hopefully), we’ll get there. Via: Wired Source: Physical Review Letters

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Scientists may have solved a key barrier to fusion power

Laser pulse study could lead to ultrafast computers

Computers that run 100, 000 times faster than current ones can change life as we know it. They could help discover distant planets more quickly or diagnose illnesses much, much earlier than usual, among other things. A team of researchers, including engineers from the University of Michigan, believe they’ve found a way to achieve that goal using extremely short laser pulses. The researchers have demoed a method to control “femtosecond” (one quadrillionth of a second) pulses of light that can move electrons quickly and efficiently. U of Michigan says it’s a step toward “lightwave electronics, ” and eventually, quantum computing . In current computers, some of the electrons moving through semiconductors bump into each other and release energy in the form of heat. That’s not very efficient computing. The researchers used crystals called gallium selenide as semiconductors and shone short laser pulses into them. These pulses move electrons into one higher energy level to the next. When the electrons move back from the higher energy levels, they emit even shorter pulses. These extremely short pulses can be used to quickly read and write information to electrons, but to be able to do that, you need to be able to control the pulses. The team found that changing the orientation of the crystals allowed them to control where the electrons go and how they move. U of Michigan explained that “because femtosecond pulses are fast enough to intercept an electron between being put into an excited state and coming down from that state, they can potentially be used for quantum computations using electrons in excited states as qubits.” While a lot of work needs to be done before we see the method used in actual working lightwave or quantum computers, this is a big step towards that goal. As Rupert Huber, lead researchers and physics professor at the University of Regensburg, said: “In the past few years, we and other groups have found that the oscillating electric field of ultrashort laser pulses can actually move electrons back and forth in solids. Everybody was immediately excited because one may be able to exploit this principle to build future computers that work at unprecedented clock rates — 10 to a hundred thousand times faster than state-of-the-art electronics.” Source: Nature Photonics , University of Michigan

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Laser pulse study could lead to ultrafast computers

Transistor with a 1nm gate size is the world’s smallest

Enlarge (credit: Sujay Desai/Berkeley Lab ) Conventional silicon-based electronics are rapidly approaching a fundamental barrier. Below about five nanometers, quantum effects make their behavior unpredictable. That’s led to research into alternative materials such as carbon nanotubes. Now, a large collaboration has taken a different material—molybdenum disulfide, or MoS 2 —and used its distinctive properties to craft a transistor that has a gate size of just one nanometer. Unfortunately, other parts of the hardware are quite a bit larger than that, and we have no way of producing these in bulk yet. But the work validates that MoS 2 ‘s properties can allow us to shrink electronics down below silicon’s limits. The idea behind the work is that a property of silicon we normally view as beneficial becomes an issue once things get small enough. That property is the mobility of electrons within silicon. On the positive side, that means the electrons move with less resistance when we want them to. It also means that they move more readily when we don’t want them to, which causes an increase in current leaking across transistors when they’re supposed to be off. Once silicon features get small enough (that 5nm limit mentioned above), leakage becomes large enough that it’s impossible to tell whether a transistor is on or off. Read 7 remaining paragraphs | Comments

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Transistor with a 1nm gate size is the world’s smallest