Ball lightning is weird: a spherical glowing object that zooms horizontally at a fast rate before vanishing. (I wonder how many UFO sightings are ball lightning.) It’s a rare phenomenon — far more so than ordinary lightning — so nobody had been able to measure its properties with scientific equipment until now. As it happened, a group of scientists in China who were studying regular lightning serendipitously spotted a ball lightning event, and measured its chemical signature. The verdict?

Now, a team of researchers serendipitously observed ball lightning at a time when they had the right equipment to study it. Jianyong Cen, Ping Yuan, and Simin Xue were in the field measuring the properties of ordinary lightning when they happened to catch ball lightning with both their high-speed cameras and their spectrographs. They found the chemical composition of the event matched that of soil. That strongly supports the hypothesis (proposed nearly fifteen years ago) that ball lightning is basically a dirt clod dislodged and heated to incandescence by a cloud-to-ground lightning strike. [Read more…]

Ball lightning and spectrum

Ball lightning’s dirty secret is dirt

Most accelerators, including the big ones at CERN and RHIC, use charged particles: protons, electrons, or ions (atoms with electrons removed to make them positively charged). That’s because it’s easy to accelerate that kind of particle using electric and magnetic fields. However, neutral particles like neutrons or normal atoms can’t be accelerated by those fields, even though they could be useful for particle colliders or bombarding materials for various reasons. A new multi-step method has solved that problem by accelerating ions, then restoring the electrons, leading to very energetic neutral atoms.

As we all know from elementary school physics, like charges repel. So any positively charged particle added to the plasma will experience acceleration from the plasma waves. Laser plasma accelerators are more compact than many other accelerator designs, including those used in big experiments like the Large Hadron Collider (LHC), although they haven’t yet reached the same energies. Plasma acceleration (sans lasers) is also important in many astrophysical processes. [Read more….]

Accelerating neutral particles on a lab bench