Metallic Hydrogen :: essays research papers fc

hydrogenthe most abundant element in the universe.Normally it has been considered to remain anon-metal at any range of temperatures andpressures. That is, until now. Recently this year,hydrogen was changed into a metallic substance,which could conduct electricity. An experimentconducted by William J. Nellis et al. at theLawrence Livermore case Laboratoryaccomplished this feat. Hydrogen was convertedfrom a non-metallic liquid, into a liquid metal. Thelikelihood that the most abundant element in theuniverse could be converted into metallic form atsufficient pressures was first theorized in 19351,but tangible evidence has eluded scientists in theintervening decades. "Metallization of hydrogenhas been the elusive Holy Grail in high-pressure natural philosophy for many years," said Bill Nellis, one ofthree Livermore researchers involved in theproject. "This is a significant contribution tocondensed matter physics because a pressure andtemperature that real produce metalliz ationhave finally been discovered."2 Livermoreresearchers Sam Weir, Art Mitchell, and BillNellis used a two-stage gas gun at Livermore tocreate enormous floor pressure on a targetcontaining liquid hydrogen cooled to 200 K (-4200 F). Sam Weir, Arthur Mitchell (a Labassociate), and Bill Nellis published the results oftheir experiments in the March 11 issue of PhysicalReview Letters under the title "Metallization ofFluid Molecular Hydrogen at 140 GPa (1.4Mbar)." When asked about the significance of thework, Nellis had this to joint "Hydrogen makes up90 percent of the universe. Jupiter is 90 percenthydrogen and contains most of the mass in ourplanetary system. Hydrogen is very important to alot of work done at the Lab. Hydrogen in the formof deuterium and tritium isotopes is the fuel inlaser-fusion targets and how it behaves at hightemperatures and pressures is very important toNova and the National Ignition Facility."3 Bymeasuring the electrical conductivity, they foundthat metallization occurs at pressure equivalent to1.4 million times Earths atmospheric pressure,nine times the sign density of hydrogen, and at atemperature of 30000 K (50000 F). Because ofthe high temperature, the hydrogen was a liquid.The intense pressure lasted less than amicrosecond. Optical evidence of a refreshed phase ofhydrogen has been previously reported using anexperimental approach that involves crushingmicroscopic-sized samples of crystalline hydrogenbetween diamond anvils.4 However, metalliccharacter has not been established. Metalliccharacter is most directly established by electricalconductivity measurements which are not yetpossible in diamond anvil cells at these pressures.The Livermore teams results were surprisingbecause of their methods, the form of hydrogenused and the pressure needed to achieve the result(which was much lower than previously believed).Virtually all predictions adjoin metallichydrogen have been made for solid hydrogen at