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DOE OSTI2023

Collimation Systems for the PSR

This note provides a review of collimator systems being used or considered in high-intensity proton accelerators like SNS, J-PARC, LHC, and PIP-II. These facilities use collimators to remove beam halo, restrict transverse size and momentum in the beam to constrain beam losses around collimators and minimize beam losses downstream, particularly losses arising from particles missing the design location at the stripping foil when injected into the proton storage ring. Collimators are placed either in the transport injection lines (single-pass collimators) or in the rings (multi-pass collimators). Collimators in the transport line are placed around stripping foils in H- accelerators, allowing the beamline optics to get rid of the unstripped protons into well localized absorbers. Rings and proton accelerators mostly rely on tungsten scrapers and collimators in a multi-stage configuration to clean the scattered beam particles mainly responsible for heavy losses at high energies. Placement of the collimators is carefully chosen in terms of the right phase advance to maximize the collimating efficiency, whether the collimation is intended to match an injection stripping foil or a downstream acceptance. Collimation systems are designed with the specific concerns of each facility in mind, although all of them prioritize the minimization of activation due to beam losses to enable hands-on access during maintenance periods. At LANSCE, there are no high-energy collimators, although pairs of horizontal and vertical jaws are routinely used in the LEBT to clean and control the transverse beam profile delivered downstream. This report will help in understanding, together with the beam dynamics simulations, which collimation schemes would be most effective for the PSR upgrade. For example, SNS designed off-momentum collimators to be placed in a 90° arc bend, a high-dispersion region in the beam injection line, very similar to the bend at Line D in LANSCE. This system was very effective at minimizing losses during injection into the SNS accumulator ring and is being re-designed for future operation.

43 PARTICLE ACCELERATORS↗

DOE OSTI2023

Hydroelectric Power and Hydrogen Production Integration

Hydropower-based hydrogen production could introduce opportunities for new revenue streams for hydropower plants, including from energy storage and regeneration as well as from sale of the hydrogen product to external markets. Hydrogen-based energy storage and regeneration could also help support Idaho Power’s decarbonization goals by decreasing dependence on fossil-based peaking power plants. Additionally, integration of hydrogen production with hydropower generation could help address the issue of low dissolved oxygen river water conditions that commonly accompany hydropower plant operations by utilizing the oxygen byproduct from an electrolytic hydrogen production process as a resource for mitigation of low dissolved oxygen water conditions. Comprehensive techno-economic analysis of the hybrid hydroelectric and hydrogen energy storage system has revealed critical insights into the pathways and considerations for optimizing the economic value and environmental benefits of such systems. Among the three identified pathways of natural gas blending, regeneration, and direct sale of hydrogen, the direct sale of hydrogen emerges as the most profitable, particularly given the current pricing dynamics of hydrogen and electricity. However, as we anticipate a future grid characterized by higher renewable energy penetration, the landscape may evolve, featuring lower average electricity prices, heightened fluctuations, and more significant seasonal variations. Consequently, the attractiveness of electricity regeneration through hydrogen and the benefits of long-duration hydrogen storage are expected to increase substantially in such a dynamic energy scenario. The careful selection of component sizes within the hybrid system proves to be paramount for ensuring cost-effectiveness. Notably, the size of the hydrogen market has emerged as a critical determinant for the optimal size of the electrolyzer. Hydrogen storage should be sized to meet energy shifting requirements. The appropriate size of the fuel cell/microturbine generator hinges on the shape of electricity prices and the available revenue streams derived from participating in grid services. Striking the right balance among these components is essential for maximizing the overall efficiency and profitability of the hydrogen facility. Furthermore, the by-product of electrolysis, namely oxygen, introduces an additional dimension to the system's functionality. The oxygen generated can be effectively utilized for dissolved oxygen (DO) mitigation, particularly with larger electrolyzer sizes capable of satisfying the complete oxygen demand for this purpose. While the economic benefits derived from saved oxygen purchase costs may be relatively modest compared to other revenue streams, the environmental advantages of repurposing oxygen for DO mitigation could help Idaho Power meet their environmental obligations. In addition to the identified factors shaping the viability of hybrid hydrogen production and hydroelectric generation, it is noteworthy that the integration of hydrogen energy storage offers a unique advantage during unusually wet years. In such periods of increased water inflow, the hydrogen storage capacity serves as a valuable supplement to the reservoir. By utilizing hydrogen energy storage as a complementary reservoir, the system gains flexibility in reservoir management when dealing with fluctuations in water availability.

08 HYDROGEN↗

DOE OSTI2026

Search for Dark Showers from Higgs Boson Decays Through the Photon Portal

One of the primary goals of the CMS detector is to find particles beyond the standard model. We present a search for dark showers produced from decays of the Higgs boson using collision data from the CMS experiment at the LHC. These dark showers then decay into jets made entirely of photons, which we can observe in the detector. Thus, our analysis focuses on reconstructing and analyzing these jets and maximizing signal selection efficiency for data from the Monte Carlo simulation. The photon signature of dark jets can then be confirmed via an invariant-mass distribution of these two photon jets. If found, these particles would provide evidence of physics theories beyond the Standard Model.

MacMullin, Alexandra [Skidmore Coll.]↗

DOE OSTI2026

Deep nonparametric estimation of operators between infinite dimensional spaces

Learning operators between infinitely dimensional spaces is an important learning task arising in machine learning, imaging science, mathematical modeling and simulations, etc. This paper studies the nonparametric estimation of Lipschitz operators using deep neural networks. Non-asymptotic upper bounds are derived for the generalization error of the empirical risk minimizer over a properly chosen network class. Under the assumption that the target operator exhibits a low dimensional structure, our error bounds decay as the training sample size increases, with an attractive fast rate depending on the intrinsic dimension in our estimation. Our assumptions cover most scenarios in real applications and our results give rise to fast rates by exploiting low dimensional structures of data in operator estimation. We also investigate the influence of network structures (e.g., network width, depth, and sparsity) on the generalization error of the neural network estimator and propose a general suggestion on the choice of network structures to maximize the learning efficiency quantitatively.

97 MATHEMATICS AND COMPUTING↗

NASA NTRS1973

Design, construction and evaluation of a 12.2 GHz, 4.0 kW-CW coupled-cavity traveling wave tube

An analytical and experimental program to study design techniques and to utilize these techniques to optimize the performance of an X-band 4 kW, CW traveling wave tube ultimately intended for satellite-borne television broadcast transmitters is described. The design is based on the coupled-cavity slow-wave circuit with velocity resynchronization to maximize the conversion efficiency. The design incorporates a collector which is demountable from the tube. This was done to facilitate multistage depressed collector experiments employing a NASA designed axisymmetric, electrostatic collector for linear beam microwave tubes after shipment of the tubes to NASA.

Ayers, W. R.↗

NASA NTRS1978

Automatic phase control in solar power satellite systems

Various approaches to the problem of generating, maintaining and distributing a coherent, reference phase signal over a large area are suggested, mathematically modeled and analyzed with respect to their ability to minimize: phase build-up, beam diffusion and beam steering phase jitter, cable length, and maximize power transfer efficiency. In addition, phase control configurations are suggested which alleviate the need for layout symmetry.

Lindsey, W. C.↗

NASA NTRS1982

Bandwidth limitations on noiseless optical channel capacity

The channel capacity of an optical communications link utilizing direct photon detection can be substantially larger than the heterodyne detection quantum limit. In the limit of a noiseless channel the capacity per received photon can even be infinite. In most communications systems the real constraint is to deliver a certain throughput capacity measured in nats/second. The current investigation has the objective to show that due to physical limitations on the minimum time resolution which can be achieved, and for any given throughput capacity in nats/second, there exists an optimum PPM word size which maximizes the 'power efficiency capacity' expressed in nats/photon. Such an optimization will allow the system-designer to minimize the amount of power needed to achieve the desired throughput without violating his bandwidth constraint.

Butman, S. A.↗

NASA NTRS1982

On the detection of other planetary systems by astrometric techniques

A quantitative method for astrometrically detecting perturbations induced in a star's motion by the presence of a planetary object is described. A periodogram is defined, wherein signals observed from a star show exactly periodic variations, which can be extracted from observational data using purely statistical methods. A detection threshold is defined for the frequency of occurrence of some detectable signal, e.g., the Nyquist frequency. Possible effects of a stellar orbital eccentricity and multiple companions are discussed, noting that assumption of a circular orbit assures the spectral purity of the signal described. The periodogram technique was applied to 12 yr of astrometric data from the U.S. Naval Observatory for three stars with low mass stellar companions. Periodic perturbations were confirmed. A comparison of the accuracy of different astrometric systems shows that the detection accuracy of a system is determined by the measurement accuracy and the number of observations, although the detection efficiency can be maximized by minimizing the number of data points for the case when observational errors are proportional to the square root of the number of data points. It is suggested that a space-based astrometric telescope is best suited to take advantage of the method.

Black, D. C.↗

NASA NTRS1985

A 250-Mbit/s ring local computer network using 1.3-microns single-mode optical fibers

A 250-Mbit/s three-station fiber-optic ring local computer network was built and successfully demonstrated. A conventional token protocol was employed for bus arbitration to maximize the bus efficiency under high loading conditions, and a non-return-to-zero (NRS) data encoding format was selected for simplicity and maximum utilization of the ECL-circuit bandwidth.

Eng, S. T.↗

NASA NTRS1987

Concepts for collection of aerosols in Titan's atmosphere

This paper considers design of instruments for collection of aerosols during entry in Titan's atmosphere. Major constraints on designs are small sample collection time, low aerosol column density, and the need to collect 1-10 micrograms of aerosol for gas chromatographic analysis. Thus, it is important to maximize aerosol collection through collector design, which includes consideration of various types of collectors, and maximizing the collection efficiency of a given type of collector. Sampling systems discussed include inertial impactors, filters, electrostatic devices, and multistage instruments. Aerosol sampling is reviewed in the context of high-altitude (200-70 km) and low-altitude (60-30 km) regions of Titan's atmosphere.

Oberbeck, Verne R.↗

NASA NTRS1987

Radiation hardening design of nuclear powered spacecraft

The design and operation of space systems utilizing nuclear fueled power systems must consider the radiation environment from the earliest stages of their design. A range of nuclear systems are being considered for present and future satellite systems capable of supplying tens of kilowatts to multimegawatt and generating a corresponding range of radiation environments. The effects of these radiations on electronics and materials can be minimized by implementing early design considerations which maximize the design efficiency and minimize the impact on system mass. Space systems design considerations for the radiation environment must include all sources in addition to the self induced gamma ray and neutron radiation. These include the orbital dependent environment from the high energy electron and protons encountered in natural space. The system trades which the designer must consider in the development of space platforms which utilize nuclear reactor power supplies are discussed.

Schmidt, R. E.↗

NASA NTRS1990

Solution techniques for the vorticity-streamfunction formulation of two-dimensional unsteady incompressible flows

A review of the solution techniques of Tezduyar et al. (1988 and 1989) for the vorticity-streamfunction formulation of two-dimensional incompressible flows is presented. While both the viscous and inviscid cases are considered, the derivation of the proper finite-element formulations for multiply connected domains is emphasized. In all formulations associated with the vorticity transport equation, the streamline upwind/Petrov-Galerkin method is used. The adaptive implicit-explicit and grouped element-by-element solution strategies are employed to maximize the computational efficiency. The solutions obtained in all test cases compare well with solutions from previously published investigations. The convergence and benchmark studies performed in this paper show that the solution techniques presented are accurate, reliable, and efficient.

Tezduyar, T. E.↗

NASA NTRS1989

AFTI/F-111 mission adaptive wing flight test instrumentation overview

The AFTI F-111 Mission Adaptive Wing (MAW) development is described together with the flight test demonstration program. The program developed a smooth variable camber wing and flight control system capable of adjusting the wing's airfoil shape in flight in response to pilot input and flight condition, in order to maximize the aerodynamic efficiency in all areas of flight envelope. This paper examines the instrumentation requirements and the systems implemented and presents the results of flight tests. These results demonstrate the practicality, airworthiness, maintainability, and performance benefits of the smooth variable camber wing system.

Bonnema, Kenneth L.↗

NASA NTRS1991

A mathematical basis for the design optimization of adaptive trusses in precision control

Optimal actuator placement schemes are presently studied for cases of adaptive truss precision control and prestressing control, with a view to the maximization of actuator efficiencies. In statically indeterminate truss structures, the optimal placement criteria and techniques differ, depending on whether the primary determinate structure is known. A suboptimal actuator-placement solution to the global optimization problem which combines displacement control and prestressing control is suggested, by combining the separate displacement control and prestressing control optimization results. Attention is given to the results obtained for the illustrative case of a two-bay, three-dimensional precision truss structure.

Das, S. K.↗

NASA NTRS1991

Operations mission planner beyond the baseline

The scheduling of Space Station Freedom must satisfy four major requirements. It must ensure efficient housekeeping operations, maximize the collection of science, respond to changes in tasking and available resources, and accommodate the above changes in a manner that minimizes disruption of the ongoing operations of the station. While meeting these requirements the scheduler must cope with the complexity, scope, and flexibility of SSF operations. This requires the scheduler to deal with an astronomical number of possible schedules. The Operations Mission Planner (OMP) is centered around minimally disruptive replanning and the use of heuristics limit search in scheduling. OMP has already shown several artificial intelligence based scheduling techniques such as Interleaved Iterative Refinement and Bottleneck Identification using Process Chronologies.

Biefeld, Eric↗

NASA NTRS1992

Compositional analysis of projectile residues on LDEF instrument AO187-1

Impact craters greater than 30 microns and associated projectile residues were analyzed by Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Analysis (EDXA). Objectives were to analyze a statistically significant number of projectiles to evaluate their chemical variability and possible clustering into discrete particle types. Bay A11 exposed six collector surfaces of anodized 1100-T4 (greater than 99 percent pure) aluminum sheets, 0.32 cm thick, yielding an exposed surface area of 1.1 sq. m. Four of the six panels have been retained at JSC, and were optically scanned, one (A11E00E) was prepared for SEM/EDX analysis. Bay A03 was occupied by high purity (99.99 percent) gold sheets, 0.5 mm thick, yielding an exposed surface area of 0.85 sq. m. Sample processing included the optical scanning (6X), labeling, and dislodging (by a punch-die device) of each individual impact greater than 75 microns for the aluminum and 30 microns for the gold. The 209 craters were dislodged form A11E00E, having crater diameters up to 3500 microns. Optical examination of the gold surfaces detected 238 craters, 198 of which were retained at JSC and analyzed via SEM/EDX. The analytical procedures included maximizing the geometric efficiency (take-off angles), using relatively long count times (500-1000 sec) and sufficiently high accelerating currents (25-30Kev). Despite diligent examination, a large number of craters did not exhibit measurable signals above background. Detectable resides were classified as either micrometeoritic or as man-made debris.

Bernhard, Ronald P.↗

NASA NTRS1992

Optimum design of high speed prop rotors including the coupling of performance, aeroelastic stability and structures

An optimization procedure is developed for the design of high speed prop-rotors to be used in civil tiltrotor applications. The goal is to couple aerodynamic performance, aeroelastic stability, and structural design requirements inside a closed-loop optimization procedure. The objective is to minimize the gross weight and maximize the propulsive efficiency in high speed cruise. Constraints are imposed on the rotor aeroelastic stability in both hover and cruise and rotor figure of merit in hover. Both structural and aerodynamic design variables are used.

Chattopadhyay, Aditi↗

NASA NTRS1993

Design of high speed proprotors using multiobjective optimization techniques

A multidisciplinary optimization procedure is developed for the design of high speed proprotors. The objectives are to simultaneously maximize the propulsive efficiency in high speed cruise without sacrificing the rotor figure of merit in hover. Since the problem involves multiple design objectives, multiobjective function formulation techniques are used. A derailed two-celled isotropic box beam is used to model the load carrying member within the rotor blade. Constraints are imposed on rotor blade aeroelastic stability in cruise, the first natural frequency in hover and total blade weight. Both aerodynamic and structural design variables are used. The results obtained using both techniques are compared to the reference rotor and show significant aerodynamic performance improvements without sacrificing dynamic and aeroelastic stability requirements.

Mccarthy, Thomas R.↗