Permanent magnet machines have become an attractive topology for several applications due to their high power density and brushless qualities as compared to conventional wound field machines or squirrel cage machines. The presences of permanent magnets provide distinct advantages, but at the same time unique behaviors that must be accounted for. Recent work has developed permanent magnet machines for high-power and high-speed applications such as may be found in the petro-chemical industry, naval ships, and energy storage systems. / text

Introduction Technetium-99m, supplied in the form of 99Mo/99mTc generators, is the most widely used radioisotope for nuclear medical imaging. The parent isotope 99Mo is currently produced in nuclear reactors. Recent disruptions in the 99Mo supply chain [1] prompted the development of methods for the direct accelerator-based production of 99mTc. Our approach involves the 100Mo(p,2n)99mTc reaction on isotopically enriched molybdenum using small medical cyclotrons (Ep ≤ 20 MeV), which is a viable method for the production of clinically useful quantities of 99mTc [2]. Multi-Curie production of 99mTc requires a 100Mo target capable of dissipating high beam intensities [3]. We have reported the fabrication of 100Mo targets of both small and large area tar-gets by electrophoretic deposition and subsequent sintering [4]. As part of our efforts to further enhance the performance of molybdenum targets at high beam currents, we have developed a novel target system (initially de-signed for the GE PETtrace cyclotron) based on a pressed and sintered 100Mo plate brazed onto a dispersion-strengthened copper backing. Materials and Methods In the first step, a molybdenum plate is produced similarly to the method described in [5] by compacting approximately 1.5 g of commercially available 100Mo powder using a cylindrical tool of 20 mm diameter. A pressure between 25 kN/cm2 and 250 kN/cm2 is applied by means of a hydraulic press. The pressed molybdenum plate is then sintered in a reducing atmosphere (Ar/2% H2) at 1,700 oC for five hours. The resulting 100Mo plates have about 90–95 % of the molybdenum bulk density. The 100Mo plate is furnace brazed at ~750 oC onto a backing manufactured from a disperse on strengthened copper composite (e.g. Glidcop AL-15) using a high temperature silver-copper brazing filler. This process yields a unique, mechanically and thermally robust target system for high beam power irradiation. Irradiations were performed on the GE PETtrace cyclotrons at LHRI and CPDC with 16.5 MeV protons and beam currents ≥ 100 µA. Targets were visually inspected after a 6 hour, 130 µA bombardment (2.73 kW/cm2, average) and were found fully intact. Up to 4.7 Ci of 99mTc have been produced to date. The saturated production yield remained constant between 2 hour and 6 hour irradiations. Results and Conclusion These results demonstrate that our brazed tar-get assembly can withstand high beam intensities for long irradiations without deterioration. Efforts are currently underway to determine maximum performance parameters.

Introduction In order to address the increasing demand for Fluorine-18 and the rising cost per mL of 18O enriched water, IBA developed improvements to their 18F- production systems. For this new design we started from scratch, with the main objectives of reducing the required enriched water volume and improving the cooling of the insert. A better cooling allows increasing the target current and thus the produced activity. Finally, we aimed to reduce the number of parts and improve the design of auxiliary components. Material and Methods Six Niobium conical inserts with different target chamber volumes were machined and tested. Only 4 of these were selected to create the new range of IBA 18F− targets shown in TABLE 1. The new Niobium target inserts have a complex shape with drilled channels on the outside of the chamber and a deep channel next to the beam strike area (FIG. 1, green circle) to ensure efficient cooling. The 18O water inlet lines are now directly inserted in the Niobium body (FIG. 1, blue circle) to improve 18F- quality (no more contact with small o-rings). In operation, a 35µm Havar® target window is used. All tests were performed using IBA Cyclone® 18 cyclotron. The targets were filled with different volumes of enriched 18O water (enrichment > 92 %) and irradiated with 18 MeV protons on target with beam currents up to 145 μA for 30 to 150 minutes, while the internal pressure rise of the target was recorded. For each target, a pressure-current curve was plotted and an optimum balance between target water fill volume, pressure and current has been determined, which maximises available activity after two hours, in each case. Results and Conclusion Radionuclidic impurities were measured and more than 100 FDG syntheses on various synthesizers confirmed the effectiveness of the new design. Increasing the current up to 145µA in Conical 16, the production reached 18 Ci in 2 hours, single beam, with a target pressure under 43 bar. Today, the use of these new targets for daily commercial production is increasing within the IBA Cyclone® installed base.

The ever-increasing popularity and usage of communication devices has resulted in power density becoming more demanding due to crowding of frequency spectrums and narrowing of bandwidths. Consequently, the power-handling capability of filters has emerged as an important research area. With the size and mass of filters shrinking to accommodate the needs of the latest technology, designing narrowband filters necessitates the operation of filters close to their maximum power capacities. Hence, there is an urgent need to properly measure and estimate power-handling capability in filter-based products such as satellite multiplexers and wireless diplexers. In this research, the design of filters and diplexers capable of handling higher power was investigated using modifications of available methods to predict the maximum input power that a filter can handle before breakdown. This method was utilized to improve the power-handling capability and quality factor of the conventional coaxial resonator while avoiding time-consuming EM simulations. A novel coaxial resonator configuration was proposed using this method and the performance of suggested configuration was validated by designing 2-pole filters using both conventional and novel configurations. A 4-pole chebyshev filter was also designed and realized using the proposed configuration, and a power-handling analysis utilizing HFSS was compared with that of the estimated value. A novel approach in the design procedure of coaxial diplexers was proposed that provided a faster design method using step-by-step group delay matching of EM simulation results with a diplexer equivalent circuit. A method for predicting air breakdown was also applied to the diplexers to determine maximum power-handling capability.

Thesis (M.S.)--Rochester Institute of Technology, 1990. / Includes bibliographical references (leaves i-ii).

Thesis (Ph. D.)--University of Texas at Austin, 2008. / Vita. Includes bibliographical references.

Thesis (M.S. in Applied Physics and M.S. in Electrical Engineering)--Naval Postgraduate School, December 2002. / Thesis advisor(s): William B. Colson, Phillip E. Pace. "AD-A411 177." Includes bibliographical references (p. 81-83). Also available online.

Thesis (M.S.)--University of Missouri-Columbia, 2004. / Typescript. Includes bibliographical references (leaves 65-67). Also available on the Internet.

Thesis (M.S. in Applied Physics and M.S. in Electrical Engineering)--Naval Postgraduate School, December 2002. / Thesis advisor(s): William B. Colson, Phillip E. Pace. Includes bibliographical references (p. 81-83). Also available online.

Thesis (M.S.)--University of Missouri-Columbia, 2004. / Typescript. Includes bibliographical references (leaves 65-67). Also available on the Internet.