Engineering topics
Publications and source records attributed to Huang, H..
Polarization lifetime for He3 using two and six snakes are studied using the T-BMT Spin Resonance Tracker code. This code integrates a reduced spinor form of the T-BMT equation including only several spin resonances and the kinematics of synchrotron motion. It was previously benchmarked against RHIC polarization lifetime under the two snake system *. * Phys. Rev.Accel. Beams 22 (2019) 9, 091001
HYBRID-E is an inertial confinement fusion implosion design that increases energy coupled to the hot spot by increasing the capsule scale in cylindrical hohlraums while operating within the current experimental limits of the National Ignition Facility. HYBRID-E reduces the hohlraum scale at a fixed capsule size compared to previous HYBRID designs, thereby increasing the hohlraum efficiency and energy coupled to the capsule, and uses the cross-beam energy transfer (CBET) to control the implosion symmetry by operating the inner (23° and 30°) and outer (44° and 50°) laser beams at different wavelengths (Δλ> 0). Small case to capsule ratio designs can suffer from insufficient drive at the waist of the hohlraum. We show that only a small amount of wavelength separation between the inner and outer beams (Δλ1-2 Å) is required to control the symmetry in low-gas-filled hohlraums (0.3 mg/cm3 He) with enough drive at the waist of the hohlraum to symmetrically drive capsules 1180 μm in outer radius. This campaign is the first to use the CBET to control the symmetry in 0.3 mg/cm3 He-filled hohlraums, the lowest gas fill density yet fielded with Δλ> 0. We find a stronger sensitivity of hot spot P2 in μm per Angstrom (40–50 μm/Å wavelength separation) than observed in high-gas-filled hohlraums and previous longer pulse designs that used a hohlraum gas fill density of 0.6 mg/cm3. There is currently no indication of transfer roll-off with increasing Δλ, indicating that even longer pulses or larger capsules could be driven using the CBET in cylindrical hohlraums. We show that the radiation flux symmetry is well controlled during the foot of the pulse, and that the entire implosion can be tuned symmetrically in the presence of the CBET in this system, with low levels of laser backscatter out of the hohlraum and low levels of hot electron production from intense laser–plasma interactions. Radiation hydrodynamic simulations can accurately represent the early shock symmetry and be used as a design tool, but cannot predict the late-time radiation flux symmetry during the peak of the pulse, and semi-empirical models are used to design the experiments. Deuterium–tritium (DT)-layered tests of 1100 μm inner radius implosions showed performance close to expectations from simulations at velocities up to ~360 km/s, and record yields at this velocity, when increasing the DT fuel layer thickness to mitigate hydrodynamic mixing of the ablator into the hot spot as a result of defects in the ablator. However, when the implosion velocity was increased, mixing due to these defects impacted performance. The ratio of measured to simulated yield for these experiments was directly correlated with the level of observed mixing. These simulations suggest that reducing the mixing, e.g., by improving the capsule defects, could result in higher performance. In addition, future experiments are planned to reduce the coast time at this scale, delay between the peak compression and the end of the laser, to increase the hot spot convergence and pressure. To reduce the coast time by several hundred ps compared to the 1100 μm inner radius implosions, HYBRID-E has also fielded 1050 μm inner radius capsules, which resulted in higher hot spot pressure and a fusion energy yield of ~170 kJ.
The extensive APEX studies of the RHIC Spin Flipper were performed during FY17 achieving up to 97 % spin flip efficiency at both injection (23.8 GeV) and store (255 GeV) energy, using 9 MHz and 197 MHz RF system. The Zgoubi simulations were setup to reproduce the experimental conditions. The results of the APEX measurements and the numerical simulations are compared here, showing a good agreement especially at injection energy. The additional simulations of the spin flip efficiency, with the 28 MHz and 197 MHz RF system, show that a stronger Spin Flipper is needed in order to achieve good (|P f /P i | > 99 %) spin flip efficiency during the nominal physics store running conditions at 255 GeV.
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The presence of a small concentration of in-plane Fe dopants in La 1.87 Sr 0.13 Cu 0.99 Fe 0.01 O 4 is known to enhance stripelike spin and charge density wave (SDW and CDW) order and suppress the superconducting T c . Here, we show that it also induces highly two-dimensional superconducting correlations that have been argued to be the signatures of a new form of superconducting order, the so-called pair density wave (PDW) order. In addition, using resonant soft x-ray scattering, we find that the two-dimensional superconducting fluctuation is strongly associated with the CDW stripe. In particular, the PDW signature first appears when the correlation length of the CDW stripe grows over eight times the lattice unit (~8 a). In conclusion, these results provide critical conditions for the formation of the PDW order.
Abstract Understanding mechanisms controlling fluid injection-triggered seismicity is key in defining strategies to ameliorate it. Recent triggered events (e.g. Pohang, Mw 5.5) have exceeded predictions of average energy release by a factor of >1000x, necessitating robust methodologies to both define critical antecedent conditions and to thereby constrain anticipated event size. We define maximum event magnitudes resulting from triggering as a function of pre-existing critical stresses and fluid injection volume. Fluid injection experiments on prestressed laboratory faults confirm these estimates of triggered moment magnitudes for varied boundary conditions and injection rates. In addition, observed ratios of shear slip to dilation rates on individual faults signal triggering and may serve as a measurable proxy for impending rupture. This new framework provides a robust method of constraining maximum event size for preloaded faults and unifies prior laboratory and field observations that span sixteen decades in injection volume and four decades in length scale.
Inertial confinement fusion implosions must achieve high in-flight shell velocity, sufficient energy coupling between the hot spot and imploding shell, and high areal density ( ρ R = ∫ ρ d r ) at stagnation. Asymmetries in ρ R degrade the coupling of shell kinetic energy to the hot spot and reduce the confinement of that energy. In this study, we present the first evidence that nonuniformity in the ablator shell thickness ( ~ 0.5 % of the total thickness) in high-density carbon experiments is a significant cause for observed 3D ρ R asymmetries at the National Ignition Facility. These shell-thickness nonuniformities have significantly impacted some recent experiments leading to ρ R asymmetries on the order of ~ 25 % of the average ρ R and hot spot velocities of ~ 100 km / s . This work reveals the origin of a significant implosion performance degradation in ignition experiments and places stringent new requirements on capsule thickness metrology and symmetry.
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In this paper, we report on eight, indirect-drive, deuterium–tritium-layered, inertial-confinement-fusion experiments at the National Ignition Facility to determine the largest capsule that can be driven symmetrically without relying on cross-beam energy transfer or advanced Hohlraum designs. Targets with inner radii of up to 1050 μm exhibited controllable P 2 symmetry, while larger capsules suffered from diminished equatorial drive. Reducing the Hohlraum gas-fill-density from 0.45 mg/cm 3 to 0.3 mg/cm 3 did not result in a favorable shift of P 2 amplitude as observed in preceding tuning experiments. Reducing the laser-entrance-hole diameter from 4 mm to 3.64 mm decreased polar radiation losses as expected, resulting in an oblate symmetry. The experiments exhibited the expected performance benefit from increased experimental scale, with yields at a fixed implosion velocity roughly following the predicted 1D dependence. With an inner radius of 1050 μm and a case-to-capsule-ratio of 3.0, experiment N181104 is the lowest implosion-velocity experiment to exceed a total neutron yield of 10 16 .
Abstract not provided.
The present RHIC beam-injection-system and one of its components the Lambertson septum magnet will be used by the EIC project to inject the hadrons from the AGS into the EIC hadron ring for further acceleration. The number of hadron bunches injected to fill the EIC ring will be almost three times as many as compared to the number of bunches to fill RHIC. The increase of the injected bunches requires new type of kickers known as “transmission line” or “strip line” kickers which provide faster rise time of ~18 nsec, but this type of kickers may not be strong enough to provide the kick required to place the injected beam trajectory into the reference orbit of the circulating beam. In this technical note we provide a modification of the RHIC injection system which consists of lowering the Lambertson septum to decrease the strength of the kickers required to place the injected beam into the reference orbit of the circulating beam.
Abstract The Raman tensor of the dominant A 1 modes of the nonlinear optical crystalline material potassium dihydrogen phosphate and its 70% deuterated analog have been ascertained. Challenges in determining the A 1 mode tensor element values based on previous reports have been resolved using a specially designed experimental setup that makes use of spherical crystal samples. This novel experimental design enabled the determination of measurement artifacts, including polarization rotation of the pump and/or scattered light propagating through the sample and the contribution of additional overlapping phonon modes, which have hindered previous efforts. Results confirmed that the polarization tensor is diagonal, and matrix elements were determined with high accuracy.
Polarized helions are part of the spin physics program for the EIC, allowing collisions of polarized neutrons with polarized electrons. Helion imperfection resonances are 2.4 times closer than protons. Helions cross two intrinsic resonances (|Gγ| = 12 - ν γ and |Gγ| = 6 + ν γ ) and six imperfection resonances |Gγ| = 5, 6, 7, 8, 9, and 10) in the Booster as they are accelerated to extraction at |Gγ| = 10.5. In this same range of γ, protons cross two imperfection resonances (|Gγ| = 3, and 4) and are extracted from the Booster prior to crossing the |Gγ| = 0 + ν γ . Preliminary benchmarking simulations are performed using protons crossing the |Gγ| = 3 and 4 imperfection resonances, results of which are compared to experimental data. The settings used for protons are extrapolated to the helion case to show there is sufficient corrector strength to preserve polarization at each imperfection resonance up to extraction.
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