Sandia National Labs is celebrating a milestone for two pulsed-energy generators that have contributed much to both basic science -- and the defense of the United States. Combined, the two particle accelerators, called Saturn and HERMES (for High-Energy Radiation Megavolt Electron Source), have fired some 4,000 and 9,000 times. respectively. Both were designed to last a decade or so, but they have proven so useful that Sandia has kept them running.
NEWS: Using Fusion to Propel an Interstellar Probe
During the Cold War, defense against nuclear attack -- such as it was -- included hardening electronics against electromagnetic pulses from nuclear explosions. A nuclear explosion releases huge amounts of gamma radiation, which knocks the electrons off of atoms in the atmosphere and generates a current that fries every electronic device within hundreds of miles. By the 1970s it was clear to both the United States and Soviet governments that either country could knock out the other's electronic communications at a stroke.
The U.S. government needed machines that generated gigantic pulses of energy. That meant particle accelerators. Saturn was first fired in 1987, and about a year later HERMES was turned on. Saturn has more raw power -- for X-ray studies it generates pulses of about 100 terawatts. HERMES is for generating gamma rays, and generates pulses of 13 terawatts. That's a lot of energy -- Saturn is firing pulses equal to 2 percent of all the electricity generated in the United States in the space of nanoseconds.
Saturn and HERMES were used initially to test the ability of electronics and other materials to stand up to the huge pulses of energy that nuclear weapons generate. But they also did a lot of basic science and still provide data that physicists use.
NEWS: Urban Nuclear Attack Scenarios Examined
Saturn, for instance, helped point the way to practical fusion. One experiment involved firing millions of amperes through tiny wires. The wires were vaporized, turned into metal ions. The powerful magnetic field that large electric currents generate pulled the ions together at high speeds, releasing X-rays. The X-rays intense enough that they could be used to compress a tiny hydrogen capsule, initiating fusion reactions. Later research has focused on getting that reaction to work constantly (as would be necessary in a power plant), but Saturn set the stage.
Meanwhile HERMES was used to show the effects of gamma rays on electronic hardware. It was first fired in 1988, but hasn't lost its place as the world's most powerful gamma ray producer. HERMES also generates lots of data for physicists, and is often used in experiments studying Bremsstrahlung radiation, which is produced when charged particles are accelerated or decelerated.
Tags: Nuclear Science, Nuclear Weapons, Physics
comments ( )