A trio of high school physics teachers recently gauged the effects of changing magnetic fields on plasma using the Current Drive Experiment-Upgrade (CDX-U), a small fusion machine at DOE's Princeton Plasma Physics Laboratory. Three of 14 teachers attending PPPL's "Plasma Camp" participated in the experiment: one operated the CDX-U with PPPL staff, the second evaluated the temperature and density of the plasma and the third analyzed plasma impurities with a soft X-ray pinhole camera. The Plasma Science and Fusion Energy Institute's camp is an intensive two-week summer program of lectures, lab work and curriculum design for high school physics teachers selected nationwide.
 

DOE's Jefferson Lab exceeded its design goal of 1,000 watts (a million times more powerful than the laser in a supermarket scanner) by producing 1,720 watts of infrared light from its Free Electron Laser (FEL) in July. At kilowatt levels, the Jefferson Lab FEL offers researchers a unique tool for science and industrial processing with light. The FEL may have a wide range of applications in manufacturing, including processing of plastics, more durable synthetic fibers, corrosion resistant metals and advanced materials and components for electronics and microtechnologies. Initial industrial experiments are investigating roughening plastics, creating hardened and corrosion-resistant metal surfaces, and machining miniature structures in ceramics.
 

Robert Nadeau

Thomas McEvilly

Ticking clusters of identical tiny earthquakes along a stretch of the San Andreas Fault reveal the rate at which two great tectonic plates are grinding past each other deep within the earth. Robert Nadeau, continuing work he began for his 1995 doctoral dissertation, and Thomas McEvilly, his former thesis advisor, have found that these "tickers" provide a new way to monitor the buildup of fault strain associated with larger earthquakes.

The two geophysicists are now colleagues in DOE's Lawrence Berkeley National Laboratory's Earth Sciences Division. They analyzed data from the Parkfield region of Central California, a long-time center of seismic study where magnitude 6 shocks have occurred every 22 years, on average, since 1857.

"Despite expectations, there hasn't been another big quake since 1966," Nadeau says. "However, a build-up of activity started in October of 1992 and persisted through 1994, including four events from magnitude 4.2 up to magnitude 5."

The researchers had earlier identified clusters of repeating small earthquakes at specific locations in the area, with virtually identical waveforms and very regular recurrence times. During the 1992-94 events, the recurrence times of these clusters accelerated.

Nadeau and McEvilly confirmed that faster recurrence in a cluster indicates accelerating slippage at particular sites deep underground. They found good agreement between the seismic data and direct measurements of slippage on the surface, made by creepmeters looking across the fault.

"It remains to be seen whether this kind of intriguing correlation exists in other fault zones, or whether it can be used over longer periods of time and space to warn us of damaging earthquakes," Nadeau cautions. "But preliminary results using small repeating earthquakes on the Hayward Fault in the San Francisco Bay Area are already showing promise."

Nadeau and McEvilly report their findings in the July 30, 1999, issue of Science magazine.

Submitted by DOE's Lawrence Berkeley National Laboratory