Transverse emittance dilution due to coupler kicks in linear accelerators

One of the main concerns in the design of low emittance linear accelerators (linacs) is the preservation of beam emittance. Here we discuss one possible source of emittance dilution, the coupler kick, due to transverse electromagnetic fields in the accelerating cavities of the linac caused by the power coupler geometry. In addition to emittance growth, the coupler kick also produces orbit distortions. It is common wisdom that emittance growth from coupler kicks can be strongly reduced by using two couplers per cavity mounted opposite each other or by having the couplers of successive cavities alternation from above to below the beam pipe so as to cancel each individual kick. We therefore analyze consequences of alternate coupler placements. We show here that for sufficiently large Q values, alternating the coupler location from before to after the cavity leads to a cancellation of the orbit distortion but not of the emittance growth, whereas alternating the coupler location from before and above to behind and below the cavity cancels the emittance growth but not the orbit distortion. These compensations hold even when each cavity is individually detuned, e.g. by microphonics. Another effective method for reducing coupler kicks that is studied is the optimization of the phase of the coupler kick. This technique is independent of the coupler geometry but relies on operating on crest. A final technique studied is symmetrization of the cavity geometry in the coupler region with the addition of a stub opposite the coupler, which reduces the amplitude of the off axis fields and is thus effective for off crest acceleration as well. We show applications of these techniques to the energy recovery linac (ERL) planned at Cornell University

Multiple Payload Adapters: Opening the Doors to Space

In order to increase the number of satellites that can be flown with reduced costs, Multiple Payload Adapters (MPAs) are needed to take advantage of excess payload capability on launch systems. This paper will discuss the development of several MPAs at the Air Force Research Laboratory Space Vehicles Directorate in support of current and future Air Force and Department of Defense requirements. The adapters are being designed using state-of-the-art manufacturing processes, launch vibration isolation, and low-shock separation technology that can accommodate multiple satellite configurations. The MPAs can deploy multiple satellites, in a large range of sizes (15 kg to 1000 kg), depending on the design configuration. The MPAs are being developed to support the Minuteman and Peacekeeper derived space launch vehicles, the Evolved Expendable Launch Vehicle, and the Space Shuttle. The successful development of these adapters will greatly reduce the cost of launching satellites into orbit by allowing for the efficient use of currently unused payload margins. These MPA concepts maximize the opportunity for low-budget satellites to be manifested for launch, and are being proposed to fly as early as 2003. Additionally, work has begun to standardize adapter configurations and connections across multiple launch vehicles to provide reduced flight integration costs and greater opportunities for inclusion of small experiments on larger missions

Critical Analytic Thinking Skills: Do They Predict Job-Related Task Performance Above and Beyond General Intelligence?

Employers and government leaders have called attention to the need for critical thinking skills in the workforce, while business trends toward evidence-based decision making also highlight the increasing importance of the critical thinking skill set. Although studies have examined the relationship of critical thinking to behaviors or job performance, many have missed a key component: incremental predictive validity of critical thinking beyond cognitive ability. The current study defines critical thinking, presents results from a test development effort in which the conceptual definition was operationalized as a measure of critical analytical thinking skills for government analysts, and presents results of a criterion validity study examining whether critical thinking skills predict technical performance generally and incrementally, beyond cognitive ability and other characteristics

Metallic and complex hydride-based electrochemical storage of energy

The development of efficient storage systems is one of the keys to the success of the energy transition. There are many ways to store energy, but among them, electrochemical storage is particularly valuable because it can store electrons produced by renewable energies with a very good efficiency. However, the solutions currently available on the market remain unsuitable in terms of storage capacity, recharging kinetics, durability, and cost. Technological breakthroughs are therefore expected to meet the growing need for energy storage. Within the framework of the Hydrogen Technology Collaboration Program—H2TCP Task-40, IEA\u27s expert researchers have developed innovative materials based on hydrides (metallic or complex) offering new solutions in the field of solid electrolytes and anodes for alkaline and ionic batteries. This review presents the state of the art of research in this field, from the most fundamental aspects to the applications in battery prototypes

Hydrogen storage in complex hydrides: past activities and new trends

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