Search NASA⌕ Search

SEARCH · Search NASA

Results for “ELECTROMAGNETIC PUMP”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Tuning of the rotational transform in Wendelstein 7-X

The control of rotational transform in Wendelstein 7-X (W7-X) is key to the island divertor operation and safety of plasma facing components. The island divertor concept in W7-X relies on an edge flux surface with rotational transform of $t$ = 1 resonating with an intrinsic n/m = 5/5 resonance to form a five lobed island chain. This island chain intersects with divertor plates to give rise to the island divertor. Changes in the relative position of the rational surface and the divertor plates can result in changes in divertor performance, thus the control of the rotational transform is essential to operation of the W7-X device. During the first divertor campaign electromagnetic loads resulted in elastic deformations of the shaped modular stellarator coils. Such deformations made these coils more planar, reducing the vacuum rotational transform, subsequently shifting the $t$ = 1 resonance outward. Unintended plasma wall interactions provided the first clear evidence of this effect during plasma operation. Flux surface measurements were utilized to estimate the correct level of current in the planar coils for correction of $t$, and found to be around ~-100 A . Scans of the planar coil current for iota correction were performed during plasma operation. These measurements suggest planar coil currents between -250 and ~ 0 A would place the strike lines at the designed distance from the pumping gaps. Divertor Langmuir and upstream probe measurements confirm these estimates along with measurements of divertor neutral gas pressure.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2015

Construction of a magnetic bottle spectrometer and its application to pulse duration measurement of X-ray laser using a pump-probe method

To characterize the temporal evolution of ultrashort X-ray pulses emitted by laser plasmas using a pump-probe method, a magnetic bottle time-of-flight electron spectrometer is constructed. The design is determined by numerical calculations of a mirror magnetic field and of the electron trajectory in a flight tube. The performance of the spectrometer is characterized by measuring the electron spectra of xenon atoms irradiated with a laser-driven plasma X-ray pulse. In addition, two-color above-threshold ionization (ATI) experiment is conducted for measurement of the X-ray laser pulse duration, in which xenon atoms are simultaneously irradiated with an X-ray laser pump and an IR laser probe. The correlation in the intensity of the sideband spectra of the 4d inner-shell photoelectrons and in the time delay of the two laser pulses yields an X-ray pulse width of 5.7 ps, in good agreement with the value obtained using an X-ray streak camera.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2020

An In-situ and Direct Confirmation of Super-Planckian Thermal Radiation Emitted From a Metallic Photonic-Crystal at Optical Wavelengths

Planck’s law predicts the distribution of radiation energy, color and intensity, emitted from a hot object at thermal equilibrium. The Law also sets the upper limit of radiation intensity, the blackbody limit. Recent experiments reveal that micro-structured tungsten can exhibit significant deviation from the blackbody spectrum. However, whether thermal radiation with weak non-equilibrium pumping can exceed the blackbody limit in the far field remains un-answered experimentally. Here, we compare thermal radiation from a micro-cavity/tungsten photonic crystal (W-PC) and a blackbody, which are both measured from the same sample and also in-situ. We show that thermal radiation can exceed the blackbody limit by >8 times at λ=1.7 μm resonant wavelength in the far-field. Our observation is consistent with a recent calculation by Wang and John performed for a 2D W-PC filament. This finding is attributed to non-equilibrium excitation of localized surface plasmon resonances coupled to nonlinear oscillators and the propagation of the electromagnetic waves through non-linear Bloch waves of the W-PC structure. This discovery could help create super-intense narrow band thermal light sources and even an infrared emitter with a laser-like input-output characteristic.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2024

EMP Testing of NAE Magnetic Motor Starters

Sandia National Laboratories (SNL) performed a high-altitude nuclear electromagnetic pulse (HEMP) critical generation station component vulnerability test campaign with a focus on high-frequency, conducted early-time (E1) HEMP for the Department of Energy (DOE) Office of Cybersecurity, Energy Security, and Emergency Response (CESER). This report provides vulnerability test results to investigate component response and/or damage thresholds to reasonable HEMP threat levels that will help to inform site vulnerability assessments, mitigation planning, and modeling calibrations. This work details testing of North American Electric (NAE) magnetic motor starters to determine the effects of conducted HEMP environments. Motor starters are the control elements that provide power to motors throughout a generating plant; a starter going offline would cause loss of power to critical pumps and compressors, which could lead to component damage or unplanned plant outages. Additionally, failed starters would be unable to support plant startup. Six industrial motor starters were tested: two 2 horsepower (HP) starters with breaker disconnects and typical protection equipment, two 20 HP starters with breaker disconnects, and two 20 HP starters with fused disconnects. Each starter was placed in a circuit with a generator and inductive motor matching the starter rating. The conducted EMP insult was injected on the power cables passing through the motor starter, with separate tests for the generator and motor sides of the starter.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2025

A mixed-integer PDE-constrained optimization formulation for constructing electromagnetic cloaks with multiple materials

We study the design of an electromagnetic cloak from multiple materials with an additional constraint on the mass of the cloak. Our problem is an example of a topology optimization problem, and we formulate this problem as a mixed-integer partial-differential equation constrained optimization (MIPDECO) problem, where Maxwell’s equation models the propagation of the wave through the cloak and surrounding medium. We use binary variables to model the assignment of the different materials, and their relevant properties (permittivity and density). The mass constraint adds a nontrivial constraint to this problem. We propose a two-phase strategy to solve this problem. In the first phase, we solve a continuous relaxation, and then propose a new variant of the feasibility pump that exploits the structure of the PDE to obtain an initial integral solution candidate. In the second phase, we use a trust-region approach to improve this incumbent. We also consider a continuation or mesh-sequencing approach to find better solutions faster on consecutively finer meshes. We present detailed numerical results to illustrate the effectiveness of our approaches for constructing multi-material cloaks with a mass constraint.

Calculus of Variations and Optimization↗
DOE OSTI2015

A reconfigurable liquid metal antenna driven by electrochemically controlled capillarity

We describe a new electrochemical method for reversible, pump-free control of liquid eutectic gallium and indium (EGaIn) in a capillary. Electrochemical deposition (or removal) of a surface oxide on the EGaIn significantly lowers (or increases) its interfacial tension as a means to induce the liquid metal in (or out) of the capillary. A fabricated prototype demonstrates this method in a reconfigurable antenna application in which EGaIn forms the radiating element. By inducing a change in the physical length of the EGaIn, the operating frequency of the antenna tunes over a large bandwidth. This purely electrochemical mechanism uses low, DC voltages to tune the antenna continuously and reversibly between 0.66 GHz and 3.4 GHz resulting in a 5:1 tuning range. Gain and radiation pattern measurements agree with electromagnetic simulations of the device, and its measured radiation efficiency varies from 41% to 70% over its tuning range.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2024

Producing entangled photon pairs and quantum squeezed states in plasmas

Plasma is capable of mediating the conversion of two pump photons into two different photons through a relativistic four-wave mixing nonlinearity. Spontaneously created photon pairs are emitted at symmetric angles with respect to the colinear pump direction, and the emission rate is largest if they have identical frequency. Thus, two orthogonally polarized pumps can produce polarization-entangled photon pairs through a millimeter-long homogeneous plasma. Here, the noise from Raman scattering can be avoided if the pump detuning differs from twice the plasma frequency. However, pump detuning exactly equal to twice the plasma frequency can significantly enhance the interaction rate, which allows for the production of strong two-mode squeezed states. Remarkably, the amplified noise from Raman scattering are correlated and hence can be suppressed in one of the output quadratures, thereby maintaining the squeezing magnitude.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2016

Integration of RFQ beam coolers and solenoidal magnetic fields

Electromagnetic traps are a flexible and powerful method of controlling particle beams, possibly of exotic nuclei, with cooling (of energy spread and transverse oscillations) provided by collisions with light gases as in the Radio Frequency Quadrupole Cooler (RFQC). A RFQC prototype can be placed inside the existing Eltrap solenoid, capable of providing a magnetic flux density component B{sub z} up to 0.2 T, where z is the solenoid axis. Confinement in the transverse plane is provided both by B{sub z} and the rf voltage V{sub rf} (up to 1 kV at few MHz). Transport is provided by a static electric field E{sub z} (order of 100 V/m), while gas collisions (say He at 1 Pa, to be maintained by differential pumping) provide cooling or heating depending on V{sub rf}. The beamline design and the major parameters V{sub rf}, B{sub z} (which affect the beam transmission optimization) are here reported, with a brief description of the experimental setup.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2022

Magnetized laser–plasma interactions in high-energy-density systems: Parallel propagation

In this study, we investigate parametric processes in magnetized plasmas, driven by a large-amplitude pump light wave. Our focus is on laser–plasma interactions relevant to high-energy-density (HED) systems, such as the National Ignition Facility and the Sandia MagLIF concept. We present a self-contained derivation of a “parametric” dispersion relation for magnetized three-wave interactions, meaning the pump wave is included in the equilibrium, similar to the unmagnetized work of Drake et al., Phys. Fluids 17, 778 (1974). For this, we use a multi-species plasma fluid model and Maxwell's equations. The application of an external B field causes right- and left-polarized light waves to propagate with differing phase velocities. This leads to Faraday rotation of the polarization, which can be significant in HED conditions. Phase-matching and linear wave dispersion relations show that Raman and Brillouin scattering have modified spectra due to the background B field, though this effect is usually small in systems of current practical interest. We study a scattering process we call stimulated whistler scattering, where a light wave decays to an electromagnetic whistler wave (ω≲ω ce ) and a Langmuir wave. This only occurs in the presence of an external B field, which is required for the whistler wave to exist.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2020

Broad band tunable energy electron beam pulser

An electromagnetic mechanical pulser implements a transverse wave metallic comb stripline TWMCS kicker having inwardly opposing teeth that retards a phase velocity of an RF traveling wave to match the kinetic velocity of a continuous electron beam, causing the beam to oscillate before being chopped into pulses by an aperture. The RF phase velocity is substantially independent of RF frequency and amplitude, thereby enabling independent tuning of the electron pulse widths and repetition rate. The TWMCS further comprises an electron pulse picker (EPP) that applies a pulsed transverse electric field across the TWMCS to deflect electrons out of the beam, allowing only selected electrons and/or groups of electrons to pass through. The EPP pulses can be synchronized with the RF traveling wave and/or with a pumping trigger of a transverse electron microscope (TEM), for example to obtain dynamic TEM images in real time.

42 ENGINEERING↗
DOE OSTI2014

Low- and high-order harmonic generation in the extended plasmas produced by laser ablation of zinc and manganese targets

The systematic studies of the harmonic generation of ultrashort laser pulses in the 5-mm-long Zn and Mn plasmas (i.e., application of nanosecond, picosecond, and femtosecond pulses for ablation, comparison of harmonic generation from atomic, ionic, and cluster-contained species of plasma, variation of plasma length, two-color pump of plasmas, etc.) are presented. The conversion efficiency of the 11th–19th harmonics generated in the Zn plasma was ∼5 × 10{sup −5}. The role of the ionic resonances of Zn near the 9th and 10th harmonics on the enhancement of harmonics is discussed. The enhancement of harmonics was also analyzed using the two-color pump of extended plasmas, which showed similar intensities of the odd and even harmonics along the whole range of generation. The harmonics up to the 107th order were demonstrated in the case of manganese plasma. The comparison of harmonic generation in the 5-mm-long and commonly used short (≤0.5 mm) plasma plumes showed the advanced properties of extended media.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2015

T-1065: Secondary Emitters Study

One possibility to make a fast and radiation resistant shower maximum (SM) detector or preshower detector is to use a secondary emitter (SE) as an active element. This method was proposed in 1990. Micro channel plates (MCP) were used as SE in the SM. The attractive properties of such SM are: 1) a two-dimensional map of energy at the SE location; 2) timing information at few tens of picosecond level, also as transverse shower size and 3) possible separation of electromagnetic and hadronic energy based on the differences of the shower size and timing. An electron-multiplier-based sampling calorimeter requires thin planar detectors at an affordable cost. Large-area photo detectors based on ALD-functionalized 20-cm-square borosilicate glass capillary micro-channel plates (MCPs), currently being developed by the LAPPD Collaboration, are candidates for the active elements. The first results of the new shower maximum detector with the micro channel plate photomultiplier (MCP-PMT) as active elements are described. The current proposal is the next natural step in this direction. The experimenters propose using large-area MCPs assembled without the usual bialkali photocathodes as the active element in sampling calorimeters. LAPPD modules without photocathodes can be economically assembled in a glove box and then pumped and sealed using the process to construct photomultipliers, bypassing the slow and expensive vacuum-transfer process required by bialkali photocathodes. The first use of electron multipliers, in this case MCPs (Fig. 1, left) as an active element in multi-layer sampling calorimeters is described. A chevron of two MCPs in vacuum, was located behind a tungsten plate on which 5 GeV and 26 GeV electrons were incident (Fig. 1, right). The amplitude of the MCP signal (Fig. 2) as a function of the tungsten thickness was measured. The primary electrons produce a shower of secondary particles, including positron-electron pairs and gammas; the response of the MCPs (Fig. 2, left) is proportional to the number of particles in the shower, which is dependent on the initial particle energy. The MCP signal shape is presented in the Fig. 2, right). The FWHM of the signal is 1 ns.

43 PARTICLE ACCELERATORS↗
DOE OSTI2015

Physical mechanisms of SiN{sub x} layer structuring with ultrafast lasers by direct and confined laser ablation

In the production process of silicon microelectronic devices and high efficiency silicon solar cells, local contact openings in thin dielectric layers are required. Instead of photolithography, these openings can be selectively structured with ultra-short laser pulses by confined laser ablation in a fast and efficient lift off production step. Thereby, the ultrafast laser pulse is transmitted by the dielectric layer and absorbed at the substrate surface leading to a selective layer removal in the nanosecond time domain. Thermal damage in the substrate due to absorption is an unwanted side effect. The aim of this work is to obtain a deeper understanding of the physical laser-material interaction with the goal of finding a damage-free ablation mechanism. For this, thin silicon nitride (SiN{sub x}) layers on planar silicon (Si) wafers are processed with infrared fs-laser pulses. Two ablation types can be distinguished: The known confined ablation at fluences below 300 mJ/cm{sup 2} and a combined partial confined and partial direct ablation at higher fluences. The partial direct ablation process is caused by nonlinear absorption in the SiN{sub x} layer in the center of the applied Gaussian shaped laser pulses. Pump-probe investigations of the central area show ultra-fast reflectivity changes typical for direct laser ablation. Transmission electron microscopy results demonstrate that the Si surface under the remaining SiN{sub x} island is not damaged by the laser ablation process. At optimized process parameters, the method of direct laser ablation could be a good candidate for damage-free selective structuring of dielectric layers on absorbing substrates.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2020

Coherent multidimensional photoelectron spectroscopy of ultrafast quasiparticle dressing by light

Abstract Depending on the applied strength, electromagnetic fields in electronic materials can induce dipole transitions between eigenstates or distort the Coulomb potentials that define them. Between the two regimes, they can also modify the electronic properties in more subtle ways when electron motion becomes governed by time and space-periodic potentials. The optical field introduces new virtual bands through Floquet engineering that under resonant conditions interacts strongly with the preexisting bands. Under such conditions the virtual bands can become real, and real ones become virtual as the optical fields and electronic band dispersions entangle the electronic response. We reveal optical dressing of electronic bands in a metal by exciting four-photon photoemission from the Cu(111) surface involving a three-photon resonant transition from the Shockley surface band to the first image potential band. Attosecond resolved interferometric scanning between identical pump–probe pulses and its Fourier analysis reveal how the optical field modifies the electronic properties of a solid through combined action of dipole excitation and field dressing.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2025

DOE SCGSR Final Report - Project Accomplishments and Additional Materials

The major accomplishments of my project were successfully developing and testing the laser interferometry diagnostic on the Plasma Liner Experiment (PLX) at Los Alamos National Laboratory (LANL). This diagnostic helped advance my research by providing a simpler way to obtain electron density measurements of magnetized plasmas compared to other electron density diagnostics such as triple Langmuir probes. The laser used was a 561 nm continuous wave (CW) diode-pumped solid state (DPSS) laser. The PLX laser interferometry diagnostic consists of two parts. These include the launching and receiving sides of the laser diagnostic. The launching side consists of the main laser beam from the DPSS laser being split into five chords(probe beams) and a reference beam which are then directed with fiber optic couplers into fiber optic cables which transmit the probe beamsto the PLX vacuum chamber. The probe beams then pass through the plasma in the chamber and into the receiving side optics where they are again directed through fiber optic cables to be combined with the reference beam. The combined beams are transmitted via multi-mode fiber optic cables to photodiodes to convert the light signals into electrical signals. Before the electrical signals get digitized, they pass through bandpass and low pass filters to eliminate electromagnetic noise and unwanted frequencies. The electrical signals are then processed by IQ demodulators to determine phase angle difference between the probe and reference beams for each chord in order to calculate line-integrated electron density.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2025

Measurement of the Neutron Electromagnetic Form Factors at High Momentum Transfer Using a Polarized 3He Target at Jefferson Lab

Ever since the composite structure of nucleons was uncovered, many experiments have been commissioned with the purpose of extracting parameters that shape our understanding of this structure. Form factors are powerful tools that rest at the forefront of the nucleon structure study. In the non-relativistic limit, they describe the magnetic and charge distributions inside the nucleon. The GEn-II experiment, which ran in Hall A of Jefferson Lab as a part of the SuperBigbite Spectrometer (SBS) program, aimed to extract the ratio of the neutron’s electric to magnetic Sachs form factors (GnE/GnM. This was accomplished using the double polarization technique: scattering polarized electrons with initial energies up to 8.45 GeV off high-density polarized 3He targets. The experiment was a coincidence measurement, with the scattered electrons detected in the BigBite Spectrometer and the recoil nucleons in a hadron calorimeter, a part of the SuperBigbite Spectrometer. The convection-style target cells used in this experiment have a 60cm long target chamber, an increase from the 40 cm cell used in the most recent polarized 3He target experiment. In addition, the cells were optically pumped from two sides of the pumping chamber. These improvements in design and functionality introduced world-record-breaking luminosity. This thesis presents preliminary results of the GEn-II experiment for the following 4-momentum transfer (Q2) values: 2.93, 6.76, and 9.78 GeV2, in addition to target performance and preliminary polarimetry results.

Presley, Hunter [Univ. of Virginia, Charlottesvill↗
DOE OSTI2021

Observation of a highly conductive warm dense state of water with ultrafast pump–probe free-electron-laser measurements

The electrical conductivity of water under extreme temperatures and densities plays a central role in modeling planetary magnetic fields. Experimental data are vital to test theories of high-energy-density water and assess the possible development and presence of extraterrestrial life. These states are also important in biology and chemistry studies when specimens in water are confined and excited using ultrafast optical or free-electron lasers (FELs). Here we utilize femtosecond optical lasers to measure the transient reflection and transmission of ultrathin water sheet samples uniformly heated by a 13.6 nm FEL approaching a highly conducting state at electron temperatures exceeding 20 000 K. The experiment probes the trajectory of water through the high-energy-density phase space and provides insights into changes in the index of refraction, charge carrier densities, and AC electrical conductivity at optical frequencies. At excitation energy densities exceeding 10 MJ/kg, the index of refraction falls to n = 0.7, and the thermally excited free-carrier density reaches ne = 5 × 1027 m−3, which is over an order of magnitude higher than that of the electron carriers produced by direct photoionization. Significant specular reflection is observed owing to critical electron density shielding of electromagnetic waves. The measured optical conductivity reaches 2 × 104 S/m, a value that is one to two orders of magnitude lower than those of simple metals in a liquid state. At electron temperatures below 15 000 K, the experimental results agree well with the theoretical calculations using density-functional theory/molecular-dynamics simulations. With increasing temperature, the electron density increases and the system approaches a Fermi distribution. In this regime, the conductivities agree better with predictions from the Ziman theory of liquid metals.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2023

Metastable argon dynamics in a pulsed microplasma at 43 GHz

Short pulses of millimeter wave (MMW) radiation at 43 GHz create microplasma within a photonic crystal for pressures from 40 to 600 Torr (1.3 × 10 3 –8.0 × 10 4 Pa). Gas breakdown occurs within a photonic crystal, which acts as an electromagnetic resonator to create a strong initial electric field. The time response of the argon metastable density is experimentally determined during the pulse and in the afterglow using laser absorption. The metastable density overshoots the steady-state condition at the beginning of the pulse and during the afterglow. Modeling is presented to understand these observations. The overproduction of argon 1s5 at the beginning of each pulse is due to a concurrent overshoot in the MMW electric field within the photonic crystal. This field overheats the plasma electrons and enhances the production of excited states. The burst of argon metastables observed in the afterglow is due to the pooled energy of the plasma stored in electrons, ions, and excited states of argon. As a result, understanding metastable production is an important intermediate step to ionization and is also critical in the study of diode-pumped rare gas lasers.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗