Separation of rare or expensive isotopes, whether radioactive or stable, requires a high efficiency of the separation process. Electromagnetic isotope separation is the most widely-used of all separation processes. Its separation efficiency depends mainly upon the ionization efficiency of its ion source. An Electron Cyclotron Resonance (ECR) ion source has been developed for the separation of both stable and radioactive isotopes on account of its high ionization efficiencies. The maximum ionization efficiencies achieved with the ECR ion source for singly charged ions for a range of materials were: radioiodine (8%), carbon (10%), nitrogen (26%), oxygen (53%), neon (31%) and xenon (83%). A computer code ECREFF, based on the atomic processes which occur in the plasma, is described for the calculation of the ionization efficiency of an ECR ion source. The experimental and calculated data are compared.

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1981. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Includes bibliographical references. / by Kenneth Edmund Kreischer. / Ph.D.

Thesis (Ph. D.)--University of Texas at Austin, 2002. / Vita. Includes bibliographical references. Available also from UMI Company.

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Cyclotron resonance has been measured in GaAs and related compounds through the use of a new experimental technique developed for the study of very pure semiconductors called optically detected cyclotron resonance (ODCR). ODCR differs from other forms of magnetospectroscopy in that the intensity of luminescence excited by a visible laser is monitored rather than the direct absorption of far-infrared radiation. The ODCR technique is initially used on an exceptionally pure sample of GaAs and resolves impurity transitions and central cell effects. An accurate measure of the electron effective mass including band nonparabolicity is made. The ODCR signal represents an interaction between the donor bound electron states and the donor bound exciton states. Standard cyclotron resonance measurements on high mobility GaAs/Ga₁-_xAl_xAs heterojunctions are performed with tilted magnetic fields. Resonant coupling between the Landau levels and electric subbands gives rise to a splitting of the cyclotron resonance lineshape which can be used to determine the subband energy spacings. This allows for a direct determination of the shape of the confinement potential which changes dramatically under different illumination conditions. A dilution refrigerator is modified in order to measure the cyclotron resonance (CR) to 100 mK of the low density, two dimensional electron system in a heterojunction. Anomalies in the CR spectrum are explained in terms of an interacting electron system composed of carriers in the two spin states of the lowest Landau level. Experimental results are presented in terms of a recent theory offered for cyclotron resonance. A series of undoped GaAs quantum wells is studied with ODCR. The conduction band mass was measured for different well widths. An offset is observed in the cyclotron resonance energy which is strongly dependent on the well width. ODCR is measured on In_0.05Ga_0.95As/GaAs superlattices using both the Faraday and Voigt magnetic field orientations. Cyclotron resonance in the Voigt geometry reveals a band structure in the growth direction. The impurity transition in the Voigt configuration shifts dramatically, moving from the bulk 1s-2p + to close to the bulk free electron field.

Thesis (Ph. D.)--Florida State University, 2004. / Advisor: Dr. Alan G. Marshall, Florida State University, College of Arts and Sciences, Institute of Molecular Biophysics. Title and description from dissertation home page (viewed June 6, 2005). Document formatted into pages; contains xix, 146 pages. Includes bibliographical references (p. 107-125).

Thesis (Ph. D.)--University of Wisconsin--Madison, 1969. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliography.

Thesis (M.S.) in Chemistry--University of Maine, 2006. / Includes vita. Includes bibliographical references (leaves 71-78).

No description available.

Durant cette thèse nous avons caractérisé et amélioré une nouvelle source de rayons X avec unplasma ECR (résonance cyclotronique électronique) permettant de générer des électronsénergétiques de 10 à 120 keV, qui vont ensuite produire le rayonnement X par freinage(bremsstrahlung). Les améliorations de l’installation ont permis d’obtenir une source stable, pouvantfonctionner une journée entière de travail (huit heures) sans arrêt. Dans la première partie de l’étudeexpérimentale on a étudié et déterminé les paramètres optimaux de la source : la pression, lapuissance micro-onde et la configuration magnétique sur le rayonnement X du plasma. Nous avonségalement confirmé la localisation des électrons énergétiques sur un anneau due à la configurationmagnétique. L’intensité trop faible et la zone d’émission non ponctuelle du rayonnement plasma, nepermettant pas l’utilisation de la source à plasma, une cible a été insérée sur la trajectoire desélectrons énergétique pour résoudre ces deux problèmes.Le principal avantage de notre source par rapport aux tubes X, est l’absence de haute tension (20 à400 kV). Pour chauffer les électrons, nous utilisons une onde de 2,45 GHz, qui est la fréquenceindustrielle autorisée dans les fours à micro-ondes, délivrée par un magnétron. Les éléments simplesqui composent notre source donne un coût plus faible qu’un système classique de tubes X, dûprincipalement au prix élevé du générateur HT pour les tubes X. De plus, nous n’avons pas besoind’un vide très poussé car, à la différence des tubes X, la source ECRX fonctionne avec une pressionrésiduelle de 0,1mPa. Et enfin notre source est compacte ce qui la rend facilement transportable. Lesapplications de cette source sont nombreuses comme la radiologie, la stérilisation et le contrôle nondestructif industriel. / During this thesis we have characterised and developed a new X-ray source with an ECR plasma(electron cyclotron resonance) generating energetic electrons from 10 to 120 keV, which will emit adeceleration radiation (the Bremsstrahlung). The improvements of the installation permit to obtain astable source, which can work during one day (eight hours) without stop. In first part of theexperimental study we have studied and determined the optimal parameters of the source: pressure,micro-wave power and the magnetic configuration on the X radiation of the plasma. We also confirmedthe localisation of the energetic electron on a ring due to the magnetic configuration. The low intensityand the non punctual emission size of the X radiation, don’t allow the use of the source, so a target isinserted in the trajectory of the energetic electron to solve these two weaknesses.The main advantage of our source compared with X-ray tubes, is the absence of high voltage (20 to400 kV). For heating the electron, we use a 2,45 GHz wave, that is the industrial frequency authorizedfor the micro-wave oven, delivered by the magnetron. The simple elements that compose our sourceare less expensive than the classical X-ray tubes, due to mainly the high cost of the X-ray generator.Moreover, we don’t need a high vacuum, mandatory for the X-ray tubes; an ECRX operates at aresidual pressure of 0,1 mPa. And finally, we have a compact source. Applications will be various frommedical, like radiological, sterilization, to non-destructive industrial control.