Thesis (Ph. D.)--University of Pennsylvania, 1936. / Bibliography: p. 115-118.

This work concerns the developnent of a proton irnuced X-ray emission (PIXEl analysis system and a multi-sample scattering chamber facility . The characteristics of the beam pulsing system and its counting rate capabilities were evaluated by observing the ion-induced X- ray pulsing operation. The characteristic X-rays were detected with a high resolution 5i(Li) detector ocoupled to a multi-channel analyser. The removal of the pile-up continuum by the use of the on-demand beam pulsing is clearly demonstrated in this work . This new on-demand pu1sing system with its counting rate capability of 25, 18 and 10 kPPS corresponding to 2, 4 am 8 used main amplifier time constant respectively enables thick targets to be analysed more readily. Reproducibility tests of the on-demand beam pulsing system operation were checked by repeated measurements of the system throughput curves, with and without beam pulsing . The reproducibility of the analysis performed using this system was also checked by repeated measurements of the intensity ratios from a number of standard binary alloys during the experimental work. A computer programme has been developed to evaluate the calculations of the X-ray yields from thick targets bombarded by protons, taking into account the secondary X-ray yield prproduction due to characteristic X- ray fluorescence from an element energetically higher than the absorption edge energy of the other element present in the target. This effect was studied on metallic binary alloys such aa Fe/Ni and Cr /Fe . The quantitative analysis of Fe/Ni and Cr/Fe alloy samples to determine their elemental composition taking into account the enhancement has been deIronstrated in this work. Furthermore , the usefulness of the Rutherford backscattering (R.B.S .) technique to obtain the depth profiles of the elements in the upper micron of the sample is discussed.

Heat pumps are becoming increasingly popular, but poor electricity generating efficiency limits the potential energy savings of electrically powered units. Thus the work reported in this thesis concerns the development of a range of gas engine driven heat pumps for industrial and commercial heating applications, which recover heat from the prime mover, normally rejected to waste. Despite the convenience of using proprietary engine heat recovery packages, investigations have highlighted the necessity to ensure the engine and the heat recovery equipment are compatible. A problem common •to all air source heat pumps is the formation of frost on the evaporator, which must be removed periodically, with the expenditure of energy, to ensure the continued operation of the plant. An original fluidised bed defrosting mechanism is proposed, which prevents the build-up of this frost, and also improves system performance. Criticisms have been levelled against the rotary sliding vane compressor, in particular the effects of lubrication, which is essential. This thesis compares the rotary sliding vane compressor with other machines, and concludes that many of these criticisms are unfounded. A confidential market survey indicates an increasing demand for heat pumps up to and including 1990, and the technical support needed to penetrate this market is presented. Such support includes the development of a range of modular gas engine driven heat pumps, and a computer aided design for the selection of the optimum units. A case study of a gas engine driven heat pump for a swimming pool application which provided valuable experience is included.

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In the present work the neutron emission spectra from a graphite cube, and from natural uranium, lithium fluoride, graphite, lead and steel slabs bombarded with 14.1 MeV neutrons were measured to test nuclear data and calculational methods for D - T fusion reactor neutronics • The neutron spectra measured were performed by an organic scintillator using a pulse shape discrimination technique based on a charge comparison method to reject the gamma rays counts. A computer programme was used to analyse the experimental data by the differentiation unfolding method. The 14.1 MeV neutron source was obtained £ran T(d,n)4He reaction by the bombardment of T - Ti target with a deuteron beam of energy 130 KeV. The total neutron yield was rronitored by the associated particle method using a silicon surface barrier detector. The numerical calculations were performed using the one - dimensional discrete - ordinate neutron transport code ANISN with the ZZ - FEWG 1/ 31 - lF cross section library. A computer programme based on Gaussian smoothing function was used to srrooth the calculated data and to match the experimental data. There was general agreement between measured and calculated spectra for the range of materials studied. The ANISN calculations carried out with P3 - S8 calculations together with representation of the slab assemblies by a hollow sphere with no reflection at the internal boundary were adequate to model the experimental data and hence it appears that the cross section set is satisfactory and for the materials tested needs no modification in the range 14.1 MeV to 2 MeV. Also it would be possible to carry out a study on fusion reactor blankets, using cylindrical geometry and including a series of concentric cylindrical shells to represent the torus wall, possible neutron converter and breeder regions, and reflector and shielding regions.

In the last few years, there has been considerable interest in using saturated magnetic objective lenses in high resolution electron microscopes. Such lenses, in present commercial electron microscopes, are energized either by conventional or superconducting coils. Very little work, however, has been reported on the use of conventional coils in saturated magnetic electron lenses. The present investigation has been concerned with the design of high flux density saturated objective lenses of both single and double polepiece types which may be energized by conventional coils and in some cases by superconducting coils. Such coils have the advantage of being small and capable of carrying high current densities. The present work has been carried out with the aid of several computer programs based on the finite element method. The effect of the shape and position of the energizing coil on the electron optical parameter has been investigated. Electron optical properties such as chromatic and spherical aberration have been studies in detail for saturated single and double polepiece lenses. Several high flux density coils of different shapes have been investigated. The choice of the most favourable coil shape and position subject to the operational requirements, has been studied in some detail. The focal properties of such optimised lenses have been computed and compared.

In this 'WOrk , the angular distributions for eTastic ·and. iBela:~ii.tc scattering of fast neutrons in fusion .reactor materials l'ia:~te<~ studied Lithium and wad material are- -likely' ';;i;"be ~n CCIUfX)nents of fusion reactor wall con£igut'atiQn qesign .. .We m=asurements were perfonnedusing an associated part;icl~,~~-; flight technique • The 14 and 14 .. 44 Mev neutrons were p~u¢ed 1;Jy. ;tli.$ T(d,n} 4He reaction with deut.erons Peinga<;eelerated in a 150kev SAME..S type Jaccelerator at ASTON and in.the 3. Mev ~~ at the Jo.i;nt Radiation. Centre I Birmingham I. res~vely; .. The q,ss.Qcj.a.~~ alpha-particles and fast. neu.tJ;qri$ Were; deteeteCl!. ~;¥.'~l :o£'·~·:p~a;§~¢; scintillator rrpunted on. a fa:st£GC1.Jsed photoroillmplj;er<t~,.;·1n~j samples used were e~ended flatpl.a:tesj of tb.icJ<n~ss~s upt.o'0~9-~... . free-path for Uthium and 1.562 Irean-fre~path fC)r ~~ • . The differential elastic seatteringcrQSs-.seefiQns· 'Wer~'tteas~ea,'for 14 Mev neutron.s for vgriousthicJmesses Qf Lithiunl ~. ~d inthel angular range from zero to; 90/ •• ]naooit.iorf , tile; angul;at':',: distributions of elastically scattered 14,.44 Mev .neutrons;·· £liein . Lithium. samples were studied in thes~' angular range: •. Inelastic scattering to the 4.63 Mev state in ~Lian<l the state I and 4 •. 1 Mev state I' in 2013Bb hay;e:been :meas~ed.T1ie,resria:Jts: . are ca:npared to ENDF!l3-IV data files and to previous fuea$ur~ts .,:' For the Lead samples the differential neutron sca,~terin9:¢:'Q$.$""'·: sections for discrete 3 Mev ranges and tile' angplardistributiQhS~lie' measured The increase in effective cross-section due tQlIJ\llt;;£plll~; . scattering effects I as the sample thic:1mess:, increas.ed:waS 'foun(~Ft.Q; . be predicted by tile empirical .relation cY =Q;:exp.(K-x}. A g96d,:E~;j;.t:Q, the eJ{perirrental data was obtained using the universa.1C0~t.;inl:.,"~i~'~ The differential elastics¢q;ttering "'crQss,,,:,,,section da:£a for,~,. . samples Qf Lithium and Lead were, a,nal:yzed in terms of' optical' nPii~it, .' calculations using the. conputer code. RARCMPPararnetersear~, procedures produced good fits' to the· cross-sections • . . For the case of thick samples of Lithium and Lead , th¢rrea:s.~ed:· angular distributions of :the scattered neutrons we.re'~p3Iesi tQ,tl1,$ .. predictions of the continuous slowing down model.