Otto H. Zinke - University of Arkansas Physics Department

Thermoelectricity in Metallic Conductors, 1978, p 29-36EVIDENCE OF AN ANOMALOUS THOMSON EFFECT/DepartmentJacovelli and 0. H. Zinkeof Physics, University of ArkansasFayetteville, Arkansas 72701 USAResearch completed since the title of this paper was submittedindicates that a more correct title would have been "Evidence ofan Anomalous Peltier Effect."The anomalous Peltier effect was discovered, however, as aresult of initial attempts by C. E. Canada and myself to measureThomson coefficients through the use of an AC magnetic Wheatstone~rid~e,' a device which senses small temperature changes in metalsample through changes in eddy-current resistance in the sample.Through the use of this device we were able to measure Thomson coefficientswhere the temperature at the point of measurement (T)was not greatly different from the local ambient temperature (To),a temperature range heretofore accessible with great difficulty formetals of low resistivity. The results of these experiments will besubmitted shortly to Physical Review. Our measured Thomson coefficientsshowed good agreement with literature values for highresistivity metals such as nickel as can be seen in Fig. 1 where ourvalues are compared to those of the most recent Thomson measurements,which were made by Maxwell, Lloyd and ~ e l l e r and , ~ an earlier measurementby ~orelius.~ For low resistivity metals such as copper andsi.lver, however, our measured Thomson coefficients showed trendstoward infinity as the difference (T-To) decreased to zero. Possiblesources of systematic and computational error did not seem to accountfor these latter observations. Analysis of our early copper dataseemed to indicate that thermal radiation was a factor.The system was redesigned to produce a single, stable value ofTo, and R. C. Norris and P. B. Jacovelli carried out an extensiveseries of measurements on a single, silver sample which are shown

Transient determinations of thermal diffusivities andemissivities of metal foilsC. E. CanadaMason urid Hurtgc,r-Silas Maso~r Cr,. Inc.. pant^..^ Pla~rt. Amurillo. Texas 79/000. H. ZinkePhysics Department, University of Arkansas, Fayetteville, Arkansas 72701(Received 5 July 1977; accepted for publication 21 September 1977)Diffusivities and emissivities are measured through the use of the transient technique for five metals.DitTusivity values for Al, Ag, Cu, Fe, and Ni are found to be 0.89, 1.73, 1.14, 0.216, and 0.176cm2/sec, and respective emissiviiy values are found to be 0.23, 0.031, 0.038, 0.046, and 0.054. Thesediffusivitia agree well with other values in literature and differ from values previously obtained throughuse or this tccl~nique becausc of corrections for heat reflection and possibly better heat input tc~hniqu~s.PACS numbers: 72.15.Eb, 44.40.+aINTRODUCTIONassumed that temperature excursions above ambientare small enoughthat the rate of heat dissipated fromThermal diffusivities and emissivities of surfaces ofthe foil surface to the surroundings can be assumed tometal foils were measured using the technique introbea linear function of (T- To). The solution where theduced by Jacovelli and Zinke.' The dissipation meainjectedheat can be considered to be a line source issurements of Jacovelli and Zinke were made with am-[carslaw and Jaeger, Eq. 10.2(9)]bient atmosphere in contact with the foils and could notbe used to determine the emissivity of the foils. Here(.r- xJ2T= Q' l,zexp(-vt--)(2)the experiments were carried out in an evacuated re- 2 WDpc(n~t) 4 ~ t Igion so that the emissivity could be calculated from the wheredissipation. The technique of injecting the heat pulseinto the foil was improved, and a temperature detectorV=~HK(W+D)/KWDZ~HK/'KD,(3)with better definition was used.andExtension of the technique to measurement in evacuatedregions revealed the possibility that systematic errorsmay have occurred in the previous measurements.Careful steps have been taken here to eliminate thosesystematic errors. Criteria were developed for systematicerror analyses, and nomographs are presentedwhich simplify the determination of reading error.Measured diffusivities and emissivities are presentedfor foils of silver, aluminum, copper, iron, and nickel.lirsults seern to be in better agreement with those ofprevious investigators than results of Jacovelli andZ inke.THEORYThe applied theory is relatively simple and straightforwardand depends on the production in the initialinstance of an instantaneous line source of heat in ametal sample where the width of the sample is muchsmaller than the length. The diffusing heat then producesa temperature change at some distance from theinput point. The change of temperature of the metalsample is calculated through the differential equationfor one-dimensional propagation of heat in a foil withsurface conduction to the surrounding medium. Theequation is [carslaw and Jaeger, Eq. 4.2 (2)]where K is the diffusivity, v is the dissipation constant,T is the temperature excursion above the ambient temperatureTo t is the time, and x is the distance. It isH = 4eoT: + H'. (4)The heat pulse is produced at xu and detected a distance(x - x,) from the point of production in a foil having widthW, thickness D, density p, specific heat C, and thermalconductivity K. The magnitude of the injected heat pulseis Q'. The quantity H corresponds to a coefficient ofheat conduction perpendicular to the foil surface. Thisquantity can be divided into a term which depends onconduction to the surrounding gas, H', and a radiationterm with e as the surface emissivity and o as theStefan-Boltzman constant. In these experiments it wasexperimentally established that H' disappeared at pressureswell over an order of magnitude greater that thehighest pressures used for the resulting data.Consequently,andValues of K and v were determined by measuring Tat x and t for two points on the temperature profile.The points chosen were the maximum value of temperatureT, occurring at t,, x,, and one of the half-maximumvalues of temperature, either TI/, or T,/, dependingon whether the designation applies to the first orsecond half-maximum. Similar designations were givento x and t. The second half-maximum was usually usedbecause of the increased reading accuracy of T31z overT,/,. The maximum temperature occurs where289 J. Appl. Phys. 49(1), January 1978 002 1 -897917814931-0289$0 1.10 O 1978 American Institute of Physics 288Downloaded 12 Jun 2009 to 130.184.237.6. Redistribution subject to AIP license or copyright; see http:lljap.aip.orgljaplcopyright.jsp

-Bulletin of the American Physj cal Society, v 22, Issue 1, D 92-92. 1977JG 6 Self-Consistency Analysis of O~ticsl Data:Aldnum.' 2. SHILES, Virginia Cmmonvealth U. andArsnne Natl. Lab. and D. Y. SMI'l'K, k ~ o ~ Iintl. n e Lob. --Ihe - .- arrtical - .- .- mo~rties -.of metallic aluminum have beeninvestigated frk the infrsred to the x-ray region ueingem d e s as a check on self-consistency of the opticalconstmts. Published compilations of data for alumjn~mby Phrcnreich, et al., Saaalti and Inokuti , a d kg-,et al.. all show violations of one or more rules exceedingexperlrrcntal or cmputational error. Re-aaalysie 02 thencst reliable experiments Indicates that available opticalconstants for aldnum belov the LII,III edge are con-sistent vith the partial f sun of 3.1 - 3.2 electronspcr ato~ predicted for the three conduction electrons perat= from Pauli principle redistribution of oscillatorstrength. K~vever, the currently accepted value8 forabsorption above the edges show an unexplainedexeeea oscillator etrength of approximstely 1.5 electronsper atom. The possibility of systematic errors in experbentor oversfnplifications in currently accepted theorywill be discussed.4Work prfomd mder the auspices of the USERDA.- a , ~as .3 K and in fields as high as 130 kG. Area databeen taken on several previously unobserved orbitseluding second zone octahedron and the third zonegym.The area data has been used to parameterizePermi surface in terms of non muffin tin KKR scattphase shifts. New cyclotron effective mess data walso be presented and discussed in terms of ,electrphonon enhancement.~010 I flection Points in SeebeckPotentia

THE PHYSICS OF FLUIDS VOLUME 14, NUMBER I JANUARY 1971Snowplowing in a Plasma Rail GunD. W. COLLIEB* AND 0. a. ZINKEDeparfmenl of Physicb, Un6era of Arkanm, Pay~lls,Arkamas 78701(Reoeiied 4 September 1988; final manuscript rewived 4 Msy 1970)Agreement between data from a plarmra rail yn aa analysed by a timeof-flight technique andpredicted by ~wplow theory indimtea that there is no necessity for any theory of drag force in thegun end seema to indiarte that om theory for drag force which also accounta for the conduotion ofelectrical current into a moving plasma ahould be re-eanmined.INTRODUCTIONOne poasible technique for studying the mannerin which electric current is conducted into a plasmfrom conducting walls is to determine the behaviorof the plasma aa it moves with respect to the wallsin a device such as a plasma gun. It has been notedby Thom, Norwood, and Jalufka' that movingplasmas never achieve expected flow velocities insuch devices. In the same article it has been postulatedthat a moving plasma may be slowed if theconduction of electric current into the plasma fromthe walh occurs through the positive ions of theplssma. The efiect has been celled drag force.'Lovberga has offered a postulate which depends on"whether the current front in the gun acts as atight piston or whether it displays permeability."Apparently technical literature by Lovberg,Gooding, and, Haywortha as quoted by Thom,Norwood, and Jaluflca' attribute the di5culty tothe "maseloading problem" which, according, tothe latter authors, "describes the technical problemof matching the inertia of the mass of the plasmato the inertia of the electrical circuitry whichpowers the gun."hae been described in some detail by Msnka4 andRoss' and used by Manka, Crawford, and Zinke'and Rosa and Zinke.' The technique yielde thetemperature (2') of the positive ions of the plaema,the flow velocity (V) of the plasma as it exit, therails, the ion population of the plaama (N), andthe time the plasma is relessed from the rails.Manka4 estimates that oscilloscope reading mrs,the principal source of error, give a 50% variationin the measured temwature and a 15% variationin the memured flow velocity. Reading errors maycause pbma releaee times to be off 6 these databy as much as several microseconds. For similarreasons the ion population may be off by a factorof 2 and is, additionally, subject to the assumptionof a fully 'ionized plasma being present. Snowplowtheory ie modified here to predict, in addition tothe flow velocity of the plasma, the temperature,the ion population, and the plasma release time.SNOWPLOW THEORYThe theory will assume that a plasma of initialpositive ion population n~ originates at one endof a rail gun and ie accelerated to the other throughIn any event, the energy lost to drag force is a neutral gas of n, atoms or .moIeculee per unitexperimentally of the same order of magnitude of length. The point of plasma initiation will be takenthe flow energy and the various theories would as z = 0. The plasma is sssumed created in aapparently have to predict loaaea of lie order of breakdown of neutral-gas caused by the dischargemagnitude. It is the purpose here to report that of an energy storage capacitor. The plasma fomif plasma drag occurs with a simple rail gun, the one component of a simple series circuit. Theenergy transferred to the drag mechanism must mowplow equation derived here will be Bimilar tobe at least an order of magnitude less than the that derived by Hart? However, the nobtion ofplasma flow- energy. Indeed, simple snowplowing Mostev, Neuringer, and Rigneyo will be d.seems to account for dl aspects of plasma behavior Kirchoffla law for a plasm8 driven by a diechargingobserved. Therefore, the variom theories for plasma capwitor is [see, e.g., Eq. (1) of Ref. 91drag should be re-examined and, in particular, thetheory of Thom, Notwood, and JaLufks1 which d(LOz +accounts for the flow of electric current into thedl+ (go + Rr + RJIplasma should be, reviewed. + e/1 ' Zdl = Vo. (I):Measurements of plssma characteristics weremade through the time-of-fight technique which The inductance L, ia ~ssociated with the oircuit i72

TRANSIENTS IN OSCILLATOR SYSTEMS 2351 K. Denbigh, The Principles of Chemical Equilibrium(Cambridge U~~iversity Press, Cambridge, England, 1968),p. 397 et seq.ST. L. Hill, Introduction to Stalistieal ThRllnodynamics(Addison-IVesley Publ. Co., Inc., &ding, Mm., 19GO),p. 86 et seq.8 See Ref. 2, p. 490 et seq.W. Born and T. von Karman, Physik. Z. 13,297 (1912).6 L. B. W, Jolley, Summation of Series (Dover Fublications,Inc., New York, 1961), p. 78.OH. Wergeland in Proceedings of the nTUFFIC InternationalSumm Course in Science, compiled by E. G. D.Cohen (North-Holland Publ. Co., Amsterdam), p. 58.Webster's New I&rnationaE Dictioaary (G. & C.hlerriam Co., Springfield, Mass.), 2nd ed., unabridged(scnles) .Lord lbyleigh, Theory of Sound (Dover Publications,Inc., New York, 1945), p. 16.M. Born, Proc. Phys. Soc. (London) 64,382 (1942).ANERICAN JOURNAL OF PHYSICS VOLUME 38. PiTjMBER 2 FEBRU.4RY 1970Bose-Einstein Condensation of Noninteracting ParticlesOTTO HENRY ZINEEDepartment of Physics, University of Arkansas, Fayetteuille, Arkansas 797'01(Received 12 June 1969; revision received 8 August 1969)Tlie cbemical potential is determined for a, Bose-Eiwtein gas of noninteracting particles in aclosed system. The calculation is done in a manner which shows dependence on an energy gap(a-a), limits of application of the results, and behavior through the transition temperature.The usual approaches to Bose-Einstein condensationfor noninteracting particles are typifiedby those of London,' Wilson,= Landau andLifschit~,~ &nd Jackson.4 The chemical potential isobtained from an expression involving a summation[see Eq. (2) below] which must be dividedfor evaluation into a single term involving thelowest energy level and a new summation [seeEq. (9) below]. London' has shown the dominantrole of the lowest energy level which leads rathernaturally to this divhion. Objections can be madewith respect t.o the evaluation of the new summation,which is inevitably integrated [see, e.g.,Eq. (4) of Ref. 1 or Eq. (6.42.4) of Ref. 21 in sucha way that the limits of application of the resultwith respect to temperature variation are notimmdately apparent. In particular, it is notapparent whether the derived expression isapplicable through the transition ternperdure. Itwill be shown below that the limits of applicationof the result are also dependent on the energydifference (a-Q). This dependence is not shownin existing derivations. Since the s term must beseparated from the series of energies representingthe levels for the noninteracting particles in a box,in principle, the eo level need not be such a level,and the energy difference (el- a) could have anyvalue. For this reason, the energy differencebetween the lowest and the next level is called a"gap" here.The approach below seems to meet the aboveob,jections. The calculations are started from theirbeginning to avoid the difficulty of correlationwith the various energy normalizations used byother authors.The average population of the jth level of acollection of noninteracting Bose-Einstein particlesisvhere gj is the statistical weight of the energystate Ej; r is the chemical potential; and all othersymbols have their usual meanings. The chemicalpotential is found as a function of N, V, T fromN= l/[exp( (ej-{)/kT] -1.1. (2)j20However, the range of values available to thechemical potential are restricted. If ei 5 T < ei+lfor some set of the macroscopic variables and somevalue of j=i, then for every jsi we have (Nj)

AMERICAN JOURNAL OF PHYSICS VOLUME 36. NUMBER 0 JUNE 1968NOTES AND DISCUSSIONElimination of the Monopole Term in the Expansionof the Magnetic Vector Potentialh o HENBY ZINKBUniuersitu of Arkansas, Fauett@rlle. Arkonsad(Received 6 February 1968)Perusal of sections of 15 modern electricity and magnetismtexts concerning the magnetic field from an arbitrarycharge distribution finds the integralrwhere mentioned, dismissed aa zero for one of two rertsons.Panofsky and Philipsll Owene, Che~ton,~ and othersindicate that the current density J can be divided intofilamentary current paths which integrate to zero. Jackson~easonsthat "For a localized steady-state currentdistribution the vol~~me integral of ] vanishes becauseV. J=O."It is not easy for students to accept that the conditionson the current distribution allow the distribution to bedivided into filamentary circuits. Criteria for such adivision are not discussed. Nor is it easy for them to- . . .- .the first integral on the right. The last integral becomesn-/Jdr=0.Since n is an arbitrary vector in magnitude and direction,it must be concluded that/Jdr=0.Note that both conditions on the current distribution areused explicitly.I W. K. H. Panofsky and M. Phillips, Classical Electricity andMagnetism (Addiion-Wesley Publ. Co., Reading, Mass., 1863).G. E. Owen, Eldromagnetic Theory (Allyn and Bacon, Boston,Mass., 1963).' W. B. Cheston, Elementary Theoru of Electric and Magnetic Fields(John Wjley &Sons, Inc., New York, 1964).J. D. Jacbon, Classical Electrodynamics (John Wiley & Sons, Ino.,New York, 1962).Conical Pendulum Experiment

Bulletin of the American Physical Society, v 20, Issue 4, p 645-645, 1975-ture is wide, the corrected resistivity is indeed proportionalto T except for small effects. The the&expansion should axso oont ribute to the deviation fromMatthiessen'a rule. The effect will be most pronouncedfor solids of high melting temperature and should alsonpply to other transport properties, including the latticethermal conductivity.'isupported by the U.S. Axmy Research Office - Durham.EP 8 Blectronic Properties of Metals at Low but Finite'Temperatures* David Y. Kojima (introduced by Isihars) andA. Isihara, State U. of N. Y. at Buffalo.--Based on agrond ensemble method, the electronic internal energy,specific heat and susceptibility have been evaluated moateccurntely for low but finite temperatures. The densitydependence of the correlation energy has been determinedin two different ways, one iterative and the otherdirect. The ring diagram contribution has also beendetermined with and without an rs expansion. Thefailure of the well-known r, series of the corrclatlonenergy will be pointed out. The temperature and densityvariations of the specific heat, the correlation energyand the para- and din-magnetic susceptibilities and thefield dependence of the Bemi momentum will be discussed.* Work supported by N.S.F.I3P 9 Temperature Dependence of the Nuclear Relaxationof 69~e in Copper Metal) G.SCHATZ~, M.RAFAILOVLCH, andG.D.SPROUSL!. SUNY-Stony Brook.--In order to study theebfecte of radiation damage on an im lanted impurity, wehave used the reaction 65~u(7~i,3n)6 ! Ge to populate tho9/2+, 7-4 usac level in 09~e. An external field of 8 kGwas npplied and the perturbed angular distribution of the398 keV decay y-ray was rueasured at target temperaturesvarying from 320K to 720K. At the hi&heat temperatura,no relaxation of the initial anisotropy (A2*0.13(1)) vaaobserved. At a temperaturs of 320K the initial anisotropywas slightly reduced (42-O.lO(1)) and a relaxation timeof 8?3 veec was observed. A preliminary interpretation ofthe relaation times is made by considering the inceractionof the impurity atom with mobile defecta introducedinto the solid by rsdiation damage. Further experimentswith exrended ranges of temperature and magnetic fieldare in progress."Supported in part by the National Science Foundation.+Mnx Kade Fellow, Univ. of Erlangen-Niirnberg, Germany.EP 10 Anomalous Behavior of Thornson Coefficients.O.A. ZINlFE and J.B. SAWYER, Univ. Ark., R.C. NORRIS,Toxaa Tnst., and C.E.CANADa, Mason and Hanger--Thornsoncoefficients direotly msaaured in this laboratory showa strong dependence on ambient temperature. Thedependence would have escaped thermocouple detection.Direct measurements by other investigators show thesame dependence although there has apparently beenno previous effort to interpet: it. he effect ssems toba aseociatod with thermal radiation.-- --Electrical Properties of Carbonized MicrocryetallineCellulose.* R. P. LYONS, JR. and J. J. SANTIAGO,Aerospace Research Laboratories, HPAFB, Ohio 45433; andF. DIAZ, University Of Puerto Rico. Rio Piebas, PuertoRico 009Y .--High purity mlcrocryat~line cellulose wascarbonized under partial vacuum at temperatures from600~~ isochrondly for 30 minutea. Electrical contactswere placed on cerefully cut samples. Both conventiondHall effect and Van der Pauw configurations were used,depending on the sise of the sample. Besistivity andHall voltages were measured from 7T°K to 298OK. Afterthe electronic transport measurements were done the samesemplea were ground in an agate mortar, and magneticsusceptibility by the Paraday method was measured in thename temperature range. The resistivity decreased withcarbonization temperature suggesting the coalescence orcarbon atom into clusters and the disappearance of thevolatile6 such as hydrogen. The diamagnetic susceptibilityremained constant with carbonization temperature(X = -0.40 * .03 X 10-6 emu/&) and its value is closeto the carbon ion core ewceptibility, suggesting theabsence of aromatic ring formation with its largeLandau-Peierls type diamagnetism. Measurements of dielectriclosses and permittivity aa iunctions of frequencywere performed.*Submitted by J.!!. Eleeseapecine? shock loaded with a gas gun has been deslgnedfor use in wmlc f'cturs studies. Thin flyer platescarried on flat-faced ~ro.lectlles lmmct the snecisenswhich are soft recoverid and examlnei netallo&aphicallyfor microaoopic spsll fracturse. The functlon of thereoovery system Is to separate the impacting projactllaand flyer plats from the Impacted speoimen to preventmbaequent unintentional specimen damage. This sepratlonla accompUshed vla ths in-fli@t capture of thepro jectlle and flyer plate. The specimen moves unhinderedafter impact until it is soft recovered in a separatearea. The systen has been successfully testedfor projeotile velooities up to 1050 ft/secl this velocityrange has been adequate for studies of microacopicspsll fracture.EP 13 -diesof In-TI All-LOW Temperatures. G.A. SAUNDERS, D.J. GUNTONand D.Y. CHUNG*, The Univ. of Durham,Enaland.--he indium-thallium alloys in the compositionrange 16-31 at.% 91 undergo a martensitic phasetransformation from higher temperature f.c.c.form to the lower temperature f.c.t. modification-a transformation which is well suited toultrasonic studies. Here we report the ultrasonicvelocity and attenuation measurementsnear the transition for a number of alloy compositionsat low temperatures. It is shown thatthe onset of instability of the f.c.c. andf.t.c. structures is directly associated withthe approach of (Cll-c12)/2 towards zero.*Present address : Physics Department, HowardUniversity. Work partially supported by N. S.F.SUPPLEMENTARY PROGRAMBP I4 gcoustic Mode Softenins and the Meltinqin In-T1 Allovs. G.A. Saundera, D. J. Guntonand D.Y. Chung*, m e Univ. of Durhm Enaland.-- The ultrasonic velocities and attenuationin several In-Tl alloys have been measuredvery close to the melting point Tm (to within0.99Tm) . These alloys showed acoustic modesoftening and lattice instability near theirmartensitic transition temperatures Tf. Thepurpose of this experiment is to correlatethe acoustic properties near the melt to thatnear T . In all the alloys measured (includingpu$e indium), no apparent phonon softingdue to the melting was observed. The resultswill be presented.*Present addrees: Physics Department, HowardUniversity. Work partially supported by N. S.F.

PBulletin of the American Physical Society, v 24, Issue 4, p 663-663, 1979device using a short pulse Nd: glass laser is proposed.A light ulse propagates in a plasma with group velocityc(l - w 9/w21k and the ponderomotive force of the photonsleaves %ehind a train of plasma waves as a wake withphase velocity same as tho photon group velocity. Suchplasma waves trap electrons and are efficient acceleratorsof electrons to high energy, Either by preaccelerationor by density gradient it might also be possible toaccelerate ions. The maximum energy electrons can gainis W = 2mc2w2/u IW = (w/o )~c~11 + (2w/w ]*(m/~)*] forionsf. Wave braaking sets limzt on the Electrostaticfield at E = mcw /e. With a laser light focused to 1018w/cm2 and plasmaPof density 10~~un'~, it will take 1 cmto accelerate electrons to 1 GeV with electrostatic fieldof lo9 V/cm through this mechanism. Computer simulationson the 1-2/2 D relativistic electromagnetic code havedemonstrated this conce t and confirm the scaling law forW at least up to (w/o 11: = 40. Applications to pulsarsand cosmic rays are agso suggested."Work supported by NSF.HI 3 Trans ort Coefficients in Halogen-Ni troqen and- Halo en-Rare &s Mixtures*. K.J. NYGAARO. S.R. HUNTER*,H.L.2~~~~K~, S.R. FOLTYN, and R.A. SIERRA, Universityof Missouri-Rol la. --Usi ng the method developed byGrunbergL, we have measured the attachment coefficientand electron drift vel oci ti es for several halogencontaininggas mixtures. Specifically, results havebeen In 12-N2, NF3-Ar, F2-Ar and CC1 -Ar, for the rangeof E/N from 1 to 40 Td (1 Td = I O ' ~ ~ ~ cm2). V Halogenconcentrations were varied from 0.1% to 1.0%, withtotal gas pressures of 10 Torr to 100 Torr. Calculationsof the rate coefficient have been made fromour data and compared to the results of otherresearchers.*Supported in part by ARPA/ONR and Los Alamos ScientificLaboratoryt~resent address: Dept. of Electrical Engineering, Uni v.of Liverpool, Liverpool , England.'Grunberg, R., Z. ~aturforkch. %a, 1039 (1969).-ssouri-Rolla. -- Trans-mixtures have been measured at total pressures rangingfrom 10 torr to 200 torr an over an /N range of40 Td 220 Td (1 Td = 10- ? 7 volt-cm 5 ). At low E/Nwhere ionization in pure CO is very small the attachmentcoefficient (n/N) has geen measured using anintegrated charge method. At higher E/N the spatialcurrent growth has been monltored to obtain bothattachement and ionization (a/N) coefficlenti. Inaddition, temporal analysis of the electron transientwave form has yielded drift velocities in these gases.The results are compared with theoretical calculationsand with existing experimental data.I*Supported in part by Los Alamos Scientific Lab~ratory.by an Einzel lens onto a magnetic analyzerwhich produced charge-state separation. Eachcharge st t was analyzed by the time-of-fllghttechniqueT*$. Excellent fits to Maxwell -~o'ltzmann distributions were observed and theplasma temperature and flow velocities werecalculated. Non-common temperatures for ionsof different charge states from single plasmasare indicated."Present address I Jet Propulsion Laboratory**Supparted by NSF Grant PHY75-259111.C.K. Manka, J.R. Crawford,and O.H. Zinke,Phys. Flulds 767 (1967).2. D.P. Ross and 0.13. Zinke, Exploding WiresVol.IV, edited by H.K. Moore and W.G. Chace,Plenum Press (1968) .HI Ofinite-Lenoth Theorv of Call~ctiv~ F~PP-E~P~~XMLase< 5. JOHNSTON, Columbia U.* The small-signalgain a free-electron laser operated in the stimulatedCompton mode is derived without limitation on thedensity of the electron beam employed. Expansion ofthe exact result in powers of the linear susceptibilitylxJ reproduces the vacuum gain formula1, and shows thatthe leading plasma correction causes a slight enhancement(not reductionl) of the vacuum gain, The theoryalso generalizes past work by including a static guidemagnetic field and an arbltrary distribution of beam. momenta: - the orinci~al assumotion is small oaln In theavailabie -. lenath (i.'e.. a reckcled system). or denserbeams (Ixl>l); it'ls shown that stimulated Comptonscattering ersists in a finite-length system, and thatthe ComptonPgain can easily rival the finite-lengthRaman gain which is derived for comparison. Thepossibility of an x-ray laser operated In this newregime (plasma-modffied Compton effect) is discussed.* Work supported by AFOSR contract F44620-75-C-0055.F.A. Hopf, P. Meystre. M.O. Scully and W.H. Louisell.Opt. Comnun. l&, 413 (1976).HI 7 Ablative accelerator desinns for light ion-.* J.H. GARDNER and J.P. BORIS, U.S. Naval ResearchLaboratory,. Light ion beams are of interest 0san energy source for ablatively driven pellets forinertlay confinement fusion. The ion beam deposits itsenergy in a much thicker region of tha ablator materialresulting in more ablator material being blown off at alower velocity and henca a lower efficiency of transferof energy to the payload. One way to overcome thin iato put a heavy tamping material at the outer edge of theablator. The mas8 of this tamping material must he chorenso that the Bragg peaks for a given ion beam villoccurr in the ablator material. A quasi-LagrangIan onedimensional hydrodynamics code has been developed whichallows an to treat interfaces of materials while nutintainingthe desirable feature6 of Flux-Corrected Transportin semi-Eulerian mode. We present results for calculationsof proton beams absorbed in a sandwich layerof gold and plastic. We investigate the optimm thicknessesof the gold and plastic layers in terms of energytransfer w d maxim= velocity obtained for the acceleratedpayload.*Work aupported by the U.S. Department of EnergyHI 8 Intense Relativistic Electron Beam Expandinginto a Pield-Free Vacuum*. F. PNRRAY**, D. PERSHING.J. SMITH, and W. 0. DOGGETT. North Carolina State Univ.,Raleigh, N. C.--An intense relativistic electron beam~roduced in NCSU's 7 ohm diode (0.5 MeV, 70 kA) is firedihrough a hole in the anode plate into e field-freevacuum. The transmitted portion of the beam expands asa result of its own self fields. A principle diagnosticemployed is blue cellophane film which is calibrated to. give current density as a function of change in transmissioncoefficient for red light. The transmissioncoefficient is determined on an optical microdensitometerwhich has been modified to accommodate He-Ne laseras its light source. The calibration constant whichrelates the current density to the change in transmissionagrees within experimental error with a pravio Y slypublished value at. much lower dose deposition rate.Preliminary result6 will be presented which show theradial beam prbfile as a function of axial positic~.*Supported by AFOSR Contract No. F49620-76-C-0007**On sabbatical leave from U. of Scranton, Scranton, PA1 ~ J. . Henley and D. Richman, Anal. 'Chem. G, 1580(1956).