Mercury ion thruster technology

The Mercury Ion Thruster Technology program was an investigation for improving the understanding of state-of-the-art mercury ion thrusters. Emphasis was placed on optimizing the performance and simplifying the design of the 30 cm diameter ring-cusp discharge chamber. Thruster performance was improved considerably; the baseline beam-ion production cost of the optimized configuration was reduced to Epsilon (sub i) perspective to 130 eV/ion. At a discharge propellant-utilization efficiency of 95 percent, the beam-ion production cost was reduced to about 155 eV/ion, representing a reduction of about 40 eV/ion over the corresponding value for the 30 cm diameter J-series thruster. Comprehensive Langmuir-probe surveys were obtained and compared with similar measurements for a J-series thruster. A successful volume-averaging scheme was developed to correlate thruster performance with the dominant plasma processes that prevail in the two thruster designs. The average Maxwellian electron temperature in the optimized ring-cusp design is as much as 1 eV higher than it is in the J-series thruster. Advances in ion-extraction electrode fabrication technology were made by improving materials selection criteria, hydroforming and stress-relieving tooling, and fabrications procedures. An ion-extraction performance study was conducted to assess the effect of screen aperture size on ion-optics performance and to verify the effectiveness of a beam-vectoring model for three-grid ion optics. An assessment of the technology readiness of the J-series thruster was completed, and operation of an 8 cm IAPS thruster using a simplified power processor was demonstrated

Oxidative Heck desymmetrisation of 2,2-disubstituted cyclopentene-1,3-diones

Oxidative Heck couplings have been successfully developed for 2,2-disubstituted cyclopentene-1,3-diones. The direct coupling onto the 2,2-disubstituted cyclopentene-1,3-dione core provides a novel expedient way of enantioselectively desymmetrising all-carbon quaternary centres

High-Power Ion Thruster Technology

Performance data are presented for the NASA/Hughes 30-cm-diam 'common' thruster operated over the power range from 600 W to 4.6 kW. At the 4.6-kW power level, the thruster produces 172 mN of thrust at a specific impulse of just under 4000 s. Xenon pressure and temperature measurements are presented for a 6.4-mm-diam hollow cathode operated at emission currents ranging from 5 to 30 A and flow rates of 4 sccm and 8 sccm. Highly reproducible results show that the cathode temperature is a linear function of emission current, ranging from approx. 1000 C to 1150 C over this same current range. Laser-induced fluorescence (LIF) measurements obtained from a 30-cm-diam thruster are presented, suggesting that LIF could be a valuable diagnostic for real-time assessment of accelerator-arid erosion. Calibration results of laminar-thin-film (LTF) erosion badges with bulk molybdenum are presented for 300-eV xenon, krypton, and argon sputtering ions. Facility-pressure effects on the charge-exchange ion current collected by 8-cm-diam and 30-cm-diam thrusters operated on xenon propellant are presented to show that accel current is nearly independent of facility pressure at low pressures, but increases rapidly under high-background-pressure conditions

Professional Development Needs of Early-Career Extension Agents Beyond the First Year: Florida County Extension Director Perspectives

Extension agents serve important roles in communities but often begin their careers lacking skills crucial for success. We aimed to understand the professional development needs of Florida early-career Extension agents beyond the first year as perceived by eight county Extension directors (CEDs). Through semistructured interviews, CEDs indicated that building community relationships, managing volunteers, communicating effectively, and other Extension-related skills are areas for which early-career Extension agents need professional development. These results suggest a need for additional development opportunities beyond the first year, with a professional development model that is continually adapted as an Extension professional\u27s skill set changes. Our findings have implications for those involved in Extension practice and research beyond Florida

Coaching and Mentoring Experiences of Early Career Extension Agents in Florida Received from County Extension Directors

County Extension directors (CEDs) are Extension agents who have both programmatic and administrative responsibilities. A critical role of Florida CEDs is to coach and mentor new Extension agents in their county office. Most literature surrounding the onboarding process of new Extension hires focuses on Extension agents within their first year on the job, with little attention on their subsequent years on the job. This study sought to understand the coaching and mentoring experiences of early career Extension agents (one to three years on the job) received from CEDs. Findings revealed eight major themes, including CED years of experience as an agent, lack of CED onboarding, and intentionality of meeting regularly. Overall, CEDs were substantially more optimistic about their early career agents’ coaching and mentoring experiences than the agents themselves, revealing a major difference in perception regarding the impact of this critical CED role. UF/IFAS Extension should provide more resources to create needed onboarding training for new CEDs and tools to help CEDs be more effective coaches and mentors for new and early career Extension agents

Assessing Florida Early Career Extension Faculty\u27s Adoption of Design Principles to Communicate Messages

Extension faculty are tasked with developing and communicating educational programs to local clientele, and communication skills are a considerable piece of the Extension faculty job. Thus, UF/IFAS Extension included a communication portion to the on-board training for newly hired Extension faculty to develop their design skills so they can more effectively communicate through their educational and marketing materials. We used Rogers’ (2003) innovation-decision process to assess Florida early career Extension faculty’s adoption of design principles after completion of the 2019 UF/IFAS Extension Faculty Development Academy. Thirty-two Extension faculty completed the spring and fall sessions of the Academy. A mixed methods approach was utilized to gather survey data at the immediate completion of the Academy and qualitative, telephone interview data four to five months after completing the Academy. The faculty retrospectively perceived they increased their knowledge about design principles. They had an overwhelmingly positive attitude about learning design principles to better their communication efforts, but they decided not to fully adopt design principles in their work as other information and elements of learning their job took precedent

Transverse Demagnetization Dynamics of a Unitary Fermi Gas

Understanding the quantum dynamics of strongly interacting fermions is a problem relevant to diverse forms of matter, including high-temperature superconductors, neutron stars, and quark-gluon plasma. An appealing benchmark is offered by cold atomic gases in the unitary limit of strong interactions. Here we study the dynamics of a transversely magnetized unitary Fermi gas in an inhomogeneous magnetic field. We observe the demagnetization of the gas, caused by diffusive spin transport. At low temperatures, the diffusion constant saturates to the conjectured quantum-mechanical lower bound $\simeq \hbar/m$, where $m$ is the particle mass. The development of pair correlations, indicating the transformation of the initially non-interacting gas towards a unitary spin mixture, is observed by measuring Tan's contact parameter.Comment: 8 pages, 6 figures. Accepted versio