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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.

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At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1992

Fe II fluorescence and anomalous C IV doublet intensities in symbiotic novae

The variation of absolute intensities of Bowen-excited Fe II emission in the symbiotic stars RR Tel, RX Pup, and AG Peg is examined. The C IV doublet intensity ratios in RR Tel were not anomalous between 1979 and 1989, and the ratio had typical values within the optically thin range. The intensity of individual Fe II Bowen-excited lines is correlated with the C IV 1548.2 A flux, suggesting the presence of a foreground Fe II region in which fluorescent-excited material responds to flux variations of C IV 1548.2 A. In RX Pup the combined fluxes of Fe II Bowen-pumped lines can account for an appreciable fraction of the flux deficit in the C IV 1548.2 A line when the C IV doublet ratio is less than the optically thick limit of unity. The Fe II Bowen lines in RX Pup exhibit a velocity range from 0 to 80 km/s, where several strong Fe II emission lines correspond to deep absorption structure in the C IV 1548.2 A line profile. In AG Peg and C IV 1548.2 A flux deficit cannot be explained by Fe II fluorescent absorption alone when the C IV doublet ratio anomaly is at an extreme.

Michalitsianos, A. G.↗
DOE OSTI2023

Utah FORGE: Reports on Northwestern Nevada Well Doublet Drilling and Testing by Fervo Energy

These reports review Fervo Energy's construction of a commercial enhanced geothermal system (EGS). Fervo has qualified full functionality of the system through production testing at commercially relevant operating conditions. The project site is located in a nearfield setting adjacent to an operating geothermal power station in north-central Nevada and is designed to deliver an uplift in high-temperature geothermal flow rates to increase the power capacity at the facility. The project involved drilling a first-of-a-kind EGS horizontal doublet well system consisting of an injection and production well pair within a high-temperature hard-rock geothermal formation. The lithology of the target reservoir is characterized as a mixed metasedimentary and igneous formation, comprised of phyllite, quartzite, diorite, and granodiorite, representative of the geology across the most prospective geothermal areas throughout the western US. This work included a 16-stage plug-and-perforate stimulation treatment which was the first of its kind in a high-temperature mixed metasedimentary and granitic formation in a fully horizontal doublet geothermal well.

15 GEOTHERMAL ENERGY↗
DOE OSTI2025

Entanglement maximization and mirror symmetry in two-Higgs-doublet models

We consider 2-to-2 scatterings of Higgs bosons in a CP-conserving two-Higgs-doublet model (2HDM) and study the implication of maximizing the entanglement in the flavor space, where the two doublets Φ a , a = 1, 2, can be viewed as a qubit: Φ 1 = |0⟩ and Φ 2 = |1⟩. More specifically, we compute the scattering amplitudes for Φ a Φ b → Φ c Φ d and require the outgoing flavor entanglement to be maximal for a full product basis such as the computational basis, which consists of {|00⟩, |01⟩, |10⟩, |11⟩}. In the unbroken phase and turning off the gauge interactions, entanglement maximization results in the appearance of an U(2) × U(2) global symmetry among the quartic couplings, which in general is broken softly by the mass terms. Interestingly, once the Higgs bosons acquire vacuum expectation values, maximal entanglement enforces an exact U(2) × U(2) symmetry, which is spontaneously broken to U(1) × U(1). As a byproduct, this gives rise to Higgs alignment as well as to the existence of 6 massless Nambu-Goldstone bosons. The U(2) × U(2) symmetry can be gauged to lift the massless Goldstones, while maintaining maximal entanglement demands the presence of a discrete Z 2 symmetry interchanging the two gauge sectors. The model is custodially invariant in the scalar sector, and the inclusion of fermions requires a mirror dark sector, related to the standard one by the Z 2 symmetry.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2021

Theoretical study of CH 3 Cl-N 2 line shapes in the ν 1 band. Line mixing effects in QR doublets and QQ k sub-branches

Line coupling and line mixing effects of CH 3 Cl lines in the ν 1 band perturbed by N 2 have been investigated. We have taken into account the non-diagonality of the exp(–S 2 ) operator within specified line spaces as well as the k-degeneracy of the transitions (due to the double degeneracy of the j,k levels with k ≠ 0). These transitions should be considered as doublets coupled by the line mixing process. A new problem appears in the calculation when the atom-atom potential model is introduced. In order to overcome this difficulty, a pragmatic approach is proposed. Comparisons of theoretically calculated matrix elements of W with measurements of QR(j,k) doublets as well as some QQ k sub-branches, which are strongly affected by line mixing, have been made. Finally, the results show that the formalism improved in this way leads to rather accurate predictions.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
NASA NTRS1976

The behavior of the Mg II doublet features near 2800 A observed in F, A, and B supergiants

The Mg II doublet features near 2800 A were recently observed in F-, A-, and B-type supergiants with a balloon-borne ultraviolet stellar spectrometer. The stars observed are Alpha UMi (F8 Ib), Alpha Per (F5 Ib), Eta Leo (A0 Ib), and Rho Leo (B1 Ib). The Mg II doublet features in Alpha UMi and Alpha Per show emission superposed on photospheric absorption. In the spectrum of Eta Leo, the Mg II lines are in absorption and show shortward-shifted components attributable to mass loss. In the spectrum of Rho Leo, the Mg II lines are primarily a composite of the photospheric and interstellar absorption features. The general behavior of the Mg II lines for supergiants of spectral types M through B are also discussed.

Kondo, Y.↗
NASA NTRS1986

The Mg 280-nm doublet as a monitor of changes in solar ultraviolet irradiance

Solar irradiance data gathered with the Nimbus 7 spacecraft from 1978-1985 are compared with atmospheric MG 289-nm doublet emission line data to evaluate the possibility of using the rotational line data to calculate the total solar UV input. The satellite instrumentation is described, including the calibration equipment and procedures. The spacecraft records solar irradiance once per day and the remainder of the time records irradiance scattered by the atmosphere. The measured irradiances are converted to equivalent brightness temperatures, which can be interpolated for specific layers of the atmosphere. Sample daily data are provided to illustrate the correlation between variations in the Mg-II core radiation and the soalr UV irradiance. Techniques are defined for correcting for periodic variations in instrument performance to quantify long-term solar UV radiance variations. Using the atmospheric Mg-II doublet radiation for measuring soalr UV irradiance is concluded of value for characterizing the effects of solar radiation on the atmosphere.

Heath, D. F.↗
NASA NTRS1989

The relative line strength and intensity of the N II 2143 doublet

The doublet emission from N II at 2139.7 A and 2143.6 A was observed by a 1.4-m scanning spectrometer with 3.1 A resolution in the daytime, high-altitude thermosphere during moderate levels of solar activity. The spectrometer viewed the earth's limb 5 deg below the local horizontal to give a nominal tangent height of 152 km. Both sub band heads of the nitric oxide gamma band system were resolved in the data at the resolution used. The emission features from N II are clearly evident on the short wavelength shoulder of the (1, 0) band. Synthetic profiles of the (1, 0) gamma band and the (0, 3) delta band of nitric oxide were fitted to the data using a chi-square analysis. These contributions were removed from the data leaving a residual emission, considered to be the N II doublet. A chi-square minimization of the data relative to a synthetic intensity profile was done. The minimum was for a line strength ratio between the 2139 A and 2143 A lines of 0.58 + or - 0.08. The mean solar EUV flux deduced from the intensity of the N II emission in this experiment is lower than other reported observations, consistent with a lower solar activity level.

Bucsela, Eric J.↗
NASA NTRS1948

The Use of Source-Sink and Doublet Distributions Extended to the Solution of Boundary-Value Problems in Supersonic Flow

A direct analogy is established between the use of source-sink and doublet distributions in the solution of specific boundary-value problems in subsonic wing theory and the corresponding problems in supersonic theory. The correct concept of the "finite part" of an integral is introduced and used in the calculation of the improper integrals associated with supersonic doublet distributions. The general equations developed are shown to include several previously published results and particular examples are given for the loading on rolling and pitching triangular wings with supersonic leading edges.

Heaslet, Max A↗
NASA NTRS2013

Surface Temperature Measurements from a Stator Vane Doublet in a Turbine Engine Afterburner Flame using Ultra-Bright Cr-Doped GdAlO3 Thermographic Phosphor

Luminescence-based surface temperature measurements from an ultra-bright Cr-doped GdAlO3 perovskite (GAP:Cr) coating were successfully conducted on an air-film-cooled stator vane doublet exposed to the afterburner flame of a J85 test engine at University of Tennessee Space Institute (UTSI). The objective of the testing at UTSI was to demonstrate that reliable thermal barrier coating (TBC) surface temperatures based on luminescence decay of a thermographic phosphor could be obtained from the surface of an actual engine component in an aggressive afterburner flame environment and to address the challenges of a highly radiant background and high velocity gases. A high-pressure turbine vane doublet from a Honeywell TECH7000 turbine engine was coated with a standard electron-beam physical vapor deposited (EB-PVD) 200-m-thick TBC composed of yttria-stabilized zirconia (YSZ) onto which a 25-m-thick GAP:Cr thermographic phosphor layer was deposited by EB-PVD. The ultra-bright broadband luminescence from the GAP:Cr thermographic phosphor is shown to offer the advantage of over an order-of-magnitude greater emission intensity compared to rare-earth-doped phosphors in the engine test environment. This higher emission intensity was shown to be very desirable for overcoming the necessarily restricted probe light collection solid angle and for achieving high signal-to-background levels. Luminescence-decay-based surface temperature measurements varied from 500 to over 1000C depending on engine operating conditions and level of air film cooling.

Eldridge, Jeffrey I.↗
NASA NTRS2015

Surface Temperature Measurements from a Stator Vane Doublet in a Turbine Engine Afterburner Flame Using a YAG:Tm Thermographic Phosphor

Luminescence-based surface temperature measurements were obtained from a YAG:Tm-coated stator vane doublet exposed to the afterburner flame of a J85 test engine at University of Tennessee Space Institute (UTSI). The objective of the testing was to demonstrate that reliable surface temperatures based on luminescence decay of a thermographic phosphor producing short-wavelength emission could be obtained from the surface of an actual engine component in a high gas velocity, highly radiative afterburner flame environment. YAG:Tm was selected as the thermographic phosphor for its blue emission at 456 nm (1D23F4 transition) and UV emission at 365 nm (1D23H6 transition) because background thermal radiation is lower at these wavelengths, which are shorter than those of many previously used thermographic phosphors. Luminescence decay measurements were acquired using a probe designed to operate in the afterburner flame environment. The probe was mounted on the sidewall of a high-pressure turbine vane doublet from a Honeywell TECH7000 turbine engine coated with a standard electron-beam physical vapor deposited (EB-PVD) 200-m-thick TBC composed of yttria-stabilized zirconia (YSZ) onto which a 25-m-thick YAG:Tm thermographic phosphor layer was deposited by solution precursor plasma spray (SPPS). Spot temperature measurements were obtained by measuring luminescence decay times at different afterburner power settings and then converting decay time to temperature via calibration curves. Temperature measurements using the decays of the 456 and 365 nm emissions are compared. While successful afterburner environment measurements were obtained to about 1300C with the 456 nm emission, successful temperature measurements using the 365 nm emission were limited to about 1100C due to interference by autofluorescence of probe optics at short decay times.

thermographic phosphor↗
NASA NTRS2021

Theoretical Study of CH3Cl-N2 Line Shapes in the ν1 Band. Line Mixing Effects in QR Doublets and QQk Sub-Branches

Line coupling and line mixing effects of CH3Cl lines in the ν1 band perturbed by N2 have been investigated. We have taken into account the non-diagonality of the exp(−S2) operator within specified line spaces as well as the k-degeneracy of the transitions (due to the double degeneracy of the j,k levels with k ≠ 0). These transitions should be considered as doublets coupled by the line mixing process. A new problem appears in the calculation when the atom-atom potential model is introduced. In order to overcome this difficulty, a pragmatic approach is proposed. Comparisons of theoretically calculated matrix elements of W with measurements of QR(j,k) doublets as well as some QQk sub-branches, which are strongly affected by line mixing, have been made. The results show that the formalism improved in this way leads to rather accurate predictions.

Methyl chloride↗
DOE OSTI2020

Cascade decays of heavy Higgs bosons through vectorlike quarks in two Higgs doublet models

We study cascade decays of heavy neutral Higgs bosons through vectorlike quarks. We focus on scenarios where decay modes into pairs of vectorlike quarks are not kinematically open which extends the sensitivity of the LHC to larger masses. Assuming only mixing with the third family of standard model quarks the new decay modes of heavy Higgs bosons are: H → t 4 t → Wbt, Ztt, htt and H → b 4 b → Wtb, Zbb, hbb, where t 4 (b 4 ) is the new up-type (down-type) quark mass eigenstate. In the numerical analysis we assume the CP even Higgs boson in the two Higgs doublet model type-II but the signatures are relevant for many other scenarios. We identify the region of the parameter space where these decay modes are significant or can even dominate, and thus they provide the best opportunities for the simultaneous discovery of a new Higgs boson and vectorlike quarks. We further explore the reach of the High Luminosity LHC for two representative decay modes,t 4 → Zt → ℓℓt and b 4 → Zb → ℓℓb, and found that cross sections at a 0.1 fb level can be probed with simple cut based analyses. We also find that the rates for Higgs cascade decays can be much larger than the rates for a single production of vectorlike quarks. Furthermore, the reach for vectorlike quarks in Higgs cascade decays and pair production extends to comparable masses.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2020

One-loop charge-breaking minima in the two-Higgs doublet model

We analyze the vacuum structure of the one-loop effective potential in the two Higgs doublet model. We find that electroweak-breaking vacuua can coexist with charge breaking ones, contradicting a theorem valid at tree-level. We perform a numerical analysis of the model and supply explicit parameter values for which charge-breaking vacuua can be the global minimum of the theory, and deeper than charge-preserving ones.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2023

Effective field theory of the two Higgs doublet model

We revisit the effective field theory of the two Higgs doublet model at tree level. The introduction of a novel basis in the UV theory allows us to derive matching coefficients in the effective description that resum important contributions from the Higgs vacuum expectation value. The new basis typically provides a significantly better approximation of the full theory prediction than the traditional approach that utilizes the Higgs basis, particularly for alignment away from the decoupling limit.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2020

Vacuum stability in inert higgs doublet model with right-handed neutrinos

We analyze the vacuum stability in the inert Higgs doublet extension of the Standard Model (SM), augmented by right-handed neutrinos (RHNs) to explain neutrino masses at tree level by the seesaw mechanism. We make a comparative study of the high- and low-scale seesaw scenarios and the effect of the Dirac neutrino Yukawa couplings on the stability of the Higgs potential. Bounds on the scalar quartic couplings and Dirac Yukawa couplings are obtained from vacuum stability and perturbativity considerations. These bounds are found to be relevant only for low-scale seesaw scenarios with relatively large Yukawa couplings. The regions corresponding to stability, metastability and instability of the electroweak vacuum are identified. These theoretical constraints give a very predictive parameter space for the couplings and masses of the new scalars and RHNs which can be tested at the LHC and future colliders. The lightest non-SM neutral CP-even/odd scalar can be a good dark matter candidate and the corresponding collider signatures are also predicted for the model.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2026

Upper bound on Parity breaking scale for doublet WIMP dark matter

A bstract We consider weakly interacting massive particle (WIMP) dark matter in a Parity solution to the strong CP problem. The WIMP phenomenology can be drastically affected by the presence of Parity partners of the WIMP and electroweak gauge bosons. We focus on a Parity extension of SU(2) L -doublet fermion dark matter, identify the viable parameter space, and derive the predictions of the theory. We find that the Parity symmetry breaking scale is bounded from above, with the bound given by 25–60 TeV, depending on whether or not dark matter and its Parity partner coannihilate with each other. The High-Luminosity Large Hadron Collider, future colliders, and direct and indirect detection experiments can probe the parameter space further, with correlated signal rates.

Baldwin, Matthew J. [University of Chicago; Univer↗
DOE OSTI2025

Observation of Persistent Zero Modes and Superconducting Vortex Doublets in UTe 2

Superconducting vortices can reveal electron pairing details and nucleate topologically protected states. Yet, vortices of bulk spin-triplet superconductors have never been visualized at the atomic scale. Recently, UTe 2 has emerged as a prime spin-triplet superconductor, but its superconducting order parameter is elusive, and whether time-reversal symmetry (TRS) is broken remains unsettled. Here, in this work, we visualize vortices on the (011) surface of ultraclean UTe 2 single crystals (T c = 2.1 K) using scanning tunneling microscopy (STM). We introduce $\frac{d^{2}𝐼}{d𝑉^{2}}$ imaging as an effective technique for vortex visualization in superconductors with substantial residual zero-energy density of states (DOS), as in UTe 2 . Anisotropic single-flux-quantum vortices, with coherence lengths of ∼12 nm (4 nm) parallel (perpendicular) to the a -axis, form a triangular vortex lattice (VL) under a small out-of-plane magnetic field. The invariance of vortex structures and VL under changes of field polarity and cooling history strongly supports time-reversal invariant superconductivity under zero field. At vortex cores (VCs), nonsplit, spectrally sharp zero-bias conductance peaks (ZBPs) persist up 8 T that are consistent with symmetry-protected Majorana zero modes (MZMs) in a topological vortex line. Close examination of vortex structures reveals a mirror-asymmetric doublet─one with ZBPs and another with an enhanced apparent gap, possibly originating from a field-induced multicomponent order parameter.

UTe2↗
DOE OSTI2023

Optically controlled single-valley exciton doublet states with tunable internal spin structures and spin magnetization generation

Manipulating quantum states through light–matter interactions has been actively pursued in two-dimensional materials research. Significant progress has been made toward the optical control of the valley degrees of freedom in semiconducting monolayer transition-metal dichalcogenides, based on doubly degenerate excitons from their two distinct valleys in reciprocal space. Here, we introduce a type of optically controllable doubly degenerate exciton states that come from a single valley, dubbed as single-valley exciton doublet (SVXD) states. They are unique in that their constituent holes originate from the same valence band, making possible the direct optical control of the spin structure of the excited constituent electrons. Combining ab initio GW plus Bethe–Salpeter equation ( GW -BSE) calculations and a theoretical analysis method, we demonstrate such SVXD in substrate-supported monolayer bismuthene—which has been successfully grown using molecular beam epitaxy. In each of the two distinct valleys in the Brillouin zone, strong spin–orbit coupling and C 3 v symmetry lead to a pair of degenerate 1s exciton states (the SVXD states) with opposite spin configurations. Any coherent linear combinations of the SVXD in a single valley can be excited by light with a specific polarization, enabling full manipulation of their internal spin configurations. In particular, a controllable net spin magnetization can be generated through light excitation. Our findings open routes to control quantum degrees of freedom, paving the way for applications in spintronics and quantum information science.

2D materials↗