# Synopsis: Electron Bounce

Experiments show that magnetic waves in a plasma may be effective at controlling energetic electrons.

Solar winds and cosmic rays continually feed charged particles into the radiation belts trapped by Earth’s magnetic field. These high-speed particles pose a hazard to space missions and orbiting satellites, so scientists are considering various schemes to drain or divert them. Now, experiments published in Physical Review Letters show that a type of magnetic wave that propagates in a plasma is unexpectedly effective at scattering trapped, energetic electrons.

Yuhou Wang at the University of California, Los Angeles, and her colleagues discovered the strong wave-particle interaction using the Large Plasma Device, a $20$-meter-long cylindrical plasma chamber, housed on the UCLA campus. With microwaves, the researchers heat a fraction of the plasma electrons, which are then trapped in a magnetic potential well, mimicking that of the Earth. In this setup, the electrons, which have energies of up to $3$ mega-electron-volts, are detected by x rays that they produce upon colliding with the chamber walls.

The magnetic field lines and surrounding plasma in the chamber are analogous to a massive string that can be “plucked” to produce waves by introducing an oscillating magnetic field. Wang et al. find that when they create such waves, called Alfvén waves, with a small radio-frequency antenna, they see a sizable burst of x rays, suggesting that the waves have strongly scattered the electrons.

For now, Wang et al.’s experiments provide a controlled environment in which to study wave-particle interactions in a plasma that could prove useful for diverting electrons in Earth’s radiation belts. – Jessica Thomas

More Features »

### Announcements

More Announcements »

## Previous Synopsis

Nonlinear Dynamics

## Next Synopsis

Atomic and Molecular Physics

## Related Articles

Optics

### Synopsis: Getting Plasma in a Twist

Laser vortex beams can exchange their optical angular momentum with a plasma from which they are reflected. Read More »

Statistical Physics

### Viewpoint: New Clues as to Why Boyajian’s Star is Dimming

A statistical analysis links a star’s mysterious brightness fluctuations to internal nonequilibrium phenomena, rather than structures orbiting around the star. Read More »

Astrophysics

### Viewpoint: Searching for Baby Planets in a Star’s Dusty Rings

Images of gaps in the dust and gas around a young star provide the best evidence to date that these gaps host newly formed planets. Read More »