This preview shows pages 1–2. Sign up to view the full content.
This preview has intentionally blurred sections. Sign up to view the full version.View Full Document
Unformatted text preview: 480 The Silicon Web: Physics for the Internet Age When electrical current passes through the gas, the fast-moving electrons collide with the He atoms, exciting some of their electrons to higher energy. These excited He atoms then collide with Ne atoms, transferring their electron excitation to the electrons in the Ne atoms. The Ne-atom electrons then undergo stimulated emission, amplifying any passing light of the proper frequency. The electric current deposits approximately 1 W of its power in the ionized gas, and only 1 milliwatt (mW) of that deposited power goes into the emitted laser beam. The rest is dissipated as heat. That is, the effi ciency of a HeNe laser is quite lowonly approximately 0.1%. IN-DEPTH LOOK 14.2: EXTREME LASER FACTS Scientists and engineers love lasers because they offer the possibility of extreme behavior. This allows scientists to probe nature on very fi ne scales and to burn holes through solid objects. To fi nd out about extreme lasersthe X-GAMES of LASERSI asked some experts 1 about the biggest, baddest, shortest, longest, slowest, fastest, and smallest lasers they knew of. These stats are from circa 2007 and are not necessarily the record holders but are important representatives of each category. The numbers in parentheses correspond to references given at the end of the chapter, where more information can be found. Highest-energy laser pulse: 150 kilojoules (kJ) in a 10-nanosecond pulse. The National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory in Livermore, California, achieved this result in 2005. The energy contained in the 150-kJ pulse is equivalent to a 1-ton automobile traveling at about 60 miles per hour. Soon, the NIF aims to achieve a pulse energy of a couple of megajoules. All of this energy will slam into a tiny pellet containing deuteriuma form of hydrogenin an effort to induce nuclear fusion, which may serve as a futuristic source of power, as well as aiding in nuclear-weapons research ....
View Full Document