Permanent Quadrupole Research Articles

Modulating the Inner Helmholtz Plane towards Stable Solid Electrolyte Interphase by Anion-π Interactions for High-Performance Anode-Free Lithium Metal Batteries.

Anode-freelithium (Li) metal batteries (AFLBs) featured high energy density are viewed as the viable future energy storage technology. However, the irregular Li deposition and unstable solid electrolyte interphase (SEI) on anode current collectors reduce their cycling performance. Here, we propose a concept of anion-recognition electrodes enabled by anion-π interactions to regulate the inner Helmholtz plane (IHP) and electrolyte solvation chemistry for high-performance AFLBs. By engineering the electrodes with electron-deficient aromatic-π systems that possess high permanent quadrupole moment (Qzz),the anion-π interactions can be generated to concentrate the anions on the electrode surface and tune the IHP structure to construct a stable anion-derived SEI layer, thus achieving highly reversible Li plating/stripping process. Through designing various current collectors with different Qzz values, the intimate correlations among the surface charge of the electrode, competitive adsorption of the IHP, and SEI structures are demonstrated. Particularly, the modified carbon cloth current collector with a high Qzz value (+35.1) delivers a high average Li stripping/plating Coulombic efficiency of 99.1% over 230 cycles in the carbonated electrolyte, enabling a long lifespan and high capacity retention of LiNi0.8Co0.1Mn0.1O2-based AFLBs with a commercial-level areal capacity (4.1 mA h cm-2).

β-Ketoenamine Porous Organic Polymers for High-Efficiency Carbon Dioxide Adsorption and Separation.

To mitigate the greenhouse effect, a number of porous organic polymers (POPs) has been developed for carbon capture. Considering the permanent quadrupole of symmetrical CO2 molecules, the integration of electron-rich groups into POPs is a feasible way to enhance the dipole-quadrupole interactions between host and guest. To comprehensively explore the effect of pore environment, including specific surface area, pore size, and number of heteroatoms, on carbon dioxide adsorption capacity, we synthesized a series of microporous POPs with different content of β-ketoenamine structures via Schiff-base condensation reactions. These materials exhibit high BET specific surface areas, high stability, and excellent CO2 adsorption capacity. It is worth mentioning that the CO2 adsorption capacity and CO2/N2 selectivity of TAPPy-TFP reaches 3.87 mmol g-1 and 27. This work demonstrates that the introduction of β-ketoenamine sites directly through condensation reaction is an effective strategy to improve the carbon dioxide adsorption performance of carbon dioxide.

Permanent magnet ECR ion source and LEBT dipole for single-ended heavy ion ToF-ERDA facility

We present the status of the ion source and low energy beam transport prototyping for a single-ended heavy ion time-of-flight elastic recoil detection analysis equipment. The environmentally friendly concept is based on a permanent magnet ECR ion source and dipole magnet on a 500 kV platform without SF6 insulation, producing high charge state noble gas ion beams, e.g. 3–6 MeV argon. The ion fluxes of Ar6+–Ar12+ achieved with the CUBE-ECRIS permanent magnet minimum-B quadrupole ion source exceed 1-10 particle nA required for the low energy ToF-ERDA application. The CUBE-ECRIS can produce over 1 particle nA krypton and xenon beams up to charge states Kr19+ and Xe24+, which enables extending the scope of the ToF-ERDA application. The integration of an adjustable-field permanent magnet dipole into the CUBE-ECRIS test stand at the JYFL accelerator laboratory is described briefly.

Towards Construction of a Novel Nanometer-Resolution MeV-STEM for Imaging Thick Frozen Biological Samples

Driven by life-science applications, a mega-electron-volt Scanning Transmission Electron Microscope (MeV-STEM) has been proposed here to image thick frozen biological samples as a conventional Transmission Electron Microscope (TEM) may not be suitable to image samples thicker than 300–500 nm and various volume electron microscopy (EM) techniques either suffering from low resolution, or low speed. The high penetration of inelastic scattering signals of MeV electrons could make the MeV-STEM an appropriate microscope for biological samples as thick as 10 μm or more with a nanoscale resolution, considering the effect of electron energy, beam broadening, and low-dose limit on resolution. The best resolution is inversely related to the sample thickness and changes from 6 nm to 24 nm when the sample thickness increases from 1 μm to 10 μm. To achieve such a resolution in STEM, the imaging electrons must be focused on the specimen with a nm size and an mrad semi-convergence angle. This requires an electron beam emittance of a few picometers, which is ~1000 times smaller than the presently achieved nm emittance, in conjunction with less than 10−4 energy spread and 1 nA current. We numerically simulated two different approaches that are potentially applicable to build a compact MeV-STEM instrument: (1) DC (Direct Current) gun, aperture, superconducting radio-frequency (SRF) cavities, and STEM column; (2) SRF gun, aperture, SRF cavities, and STEM column. Beam dynamic simulations show promising results, which meet the needs of an MeV-STEM, a few-picometer emittance, less than 10−4 energy spread, and 0.1–1 nA current from both options. Also, we designed a compact STEM column based on permanent quadrupole quintuplet, not only to demagnify the beam size from 1 μm at the source point to 2 nm at the specimen but also to provide the freedom of changing the magnifications at the specimen and a scanning system to raster the electron beam across the sample with a step size of 2 nm and the repetition rate of 1 MHz. This makes it possible to build a compact MeV-STEM and use it to study thick, large-volume samples in cell biology.

Design of A Permanent Quadrupole Magnet with Adjustable Magnetic Field Gradient

As compared to traditional magnets, permanent magnets can effectively reduce energy consumption and eliminate the impact of current ripple and the water cooling system on beam current. The use of permanent magnets in accelerators has become a new trend as permanent magnet technology has advanced. In HALF (Hefei Advanced Light Facility), we have designed a permanent magnet based on the quadrupole magnet, and the central magnetic field strength of the permanent magnet can be adjusted, indicating that single or multiple permanent magnets can be developed to replace different sizes of quadrupole magnets in accelerators, greatly improving systematization. The magnet’s mechanical design has been finalized, and the prototype of the permanent magnet will be manufactured and tested soon.

Kinetic and Parametric Analysis of the Separation of Ultra-Small, Aqueous Superparamagnetic Iron Oxide Nanoparticle Suspensions under Quadrupole Magnetic Fields.

Superparamagnetic iron oxide nanoparticles (SPIONs) have gathered tremendous scientific interest, especially in the biomedical field, for multiple applications, including bioseparation, drug delivery, etc. Nevertheless, their manipulation and separation with magnetic fields are challenging due to their small size. We recently reported the coupling of cooperative magnetophoresis and sedimentation using quadrupole magnets as a promising strategy to successfully promote SPION recovery from media. However, previous studies involved SPIONs dispersed in organic solvents (non-biocompatible) at high concentrations, which is detrimental to the process economy. In this work, we investigate, for the first time, the magnetic separation of 20 nm and 30 nm SPIONs dispersed in an aqueous medium at relatively low concentrations (as low as 0.5 g·L-1) using our custom, permanent magnet-based quadrupole magnetic sorter (QMS). By monitoring the SPION concentrations along the vessel within the QMS, we estimated the influence of several variables in the separation and analyzed the kinetics of the process. The results obtained can be used to shed light on the dynamics and interplay of variables that govern the fast separation of SPIONs using inexpensive permanent magnets.

Slit extraction and emittance results of a permanent magnet minimum-B quadrupole electron cyclotron resonance ion source

We present an experimental and simulation study of high charge state ion beams produced with a permanent magnet electron cyclotron resonance ion source (ECRIS) with minimum-B quadrupole magnetic field topology and slit extraction system. The unconventional topology generates fan-shaped plasma flux, favouring a rectangular aperture for beam extraction. We demonstrate successful low-energy transport of the slit beam, achieving up to 25 times higher beam currents compared to a round extraction aperture. Maximum beam intensities are 1.5 and 15 μA for argon 11＋ and 9＋, respectively. The results indicate microwave power-limited beam production. Emittance values are comparable to traditional ECRIS. Unlike in conventional ECRIS, the emittance increases monotonically with increasing charge state due to slit extraction, magnetic topology, and beam transport characteristics. The experimental transport efficiency for helium ranges from 32% to 50%, depending on the total beam current. The losses primarily occur due to the dipole magnet’s insufficient vertical aperture.

Transport Parameters for Combustion Species Based on cAMOEBA Polarizable Force Field.

In this study, we report a simplified yet accurate general AMOEBA polarizable force field for combustion-interested molecular species, denoted as Combustion-AMOEBA or cAMOEBA. By eliminating the permanent atomic dipoles and quadrupoles, retaining the explicit polarization and defining the general atom types of each molecule species, including alkanes, alkenes, alkynes, alcohols, peroxides, and aldehydes, a simplified and general cAMOEBA force field was constructed and validated using the benchmark results obtained at the QCISD(T)/CBS level of theory. In this way, the tedious parametrization step for permanent atomic multipoles of each new molecule in the original AMOEBA (Poltype/MP2) force field could be avoided, hence providing the capability of accurate high-throughput calculation for a large number of molecules at lower computational cost. The averaged difference between the calculated transport parameters, σ and ε, for approximately 100 different molecules and four bath gases (He, Ne, Ar, and N2) using cAMOEBA and AMOEBA (Poltype/MP2) are of 0.09% and 1.27%, respectively, showing a good consistence of the general cAMOEBA force field with the original AMOEBA (Poltype/MP2) force field where the multipole force field parameters were obtained from quantum mechanical calculation for each small molecule. Our results also indicated that the Lorentz-Berthelot combination rule was more applicable than Waldman-Hagler for obtaining the molecular Lennard-Jones parameters of pure gases from one bath gas, while the Waldman-Hagler combination rule was better for obtaining such parameters from all four bath gases. The pure gas parameters obtained using cAMOEBA can be applied to develop high quality transport property database for combustion modeling.

Sample-shape dependent energy levels in organic semiconductors

Energy levels in an organic semiconductor are mainly determined by the molecular orbital energies of the constituent molecules. Recent studies, however, have revealed that the energy levels can be altered as much as 1 eV by the molecular orientation in the film or the molecular mixing ratio in the binary film, owing to the intermolecular electrostatic interaction. Because of the long-range nature of Coulomb interaction, theory predicts that the electrostatic energy should depend on the sample shape. In this article, we examine the coverage-dependent energy levels of zinc phthalocyanine and per-fluorinated zinc phthalocyanine in the submonolayer region with ultraviolet photoelectron spectroscopy (UPS) and low-energy inverse photoelectron spectroscopy (LEIPS). Using the procedure we reported previously, we separately evaluated the electronic polarization energy and electrostatic energy as a function of coverage. Unlike the electronic polarization, which contributes only as much as 10 meV, the electrostatic energy contributes as much as 120 meV to the coverage-dependent energy shift. We conclude that the shift in energy levels by changing the coverage is attributed to the sample shape-dependent energy level, owing to the long-range nature of the charge--permanent quadrupole interaction.

Induced quantum gravitational interaction between two objects with permanent quadrupoles in external gravitational fields

We investigate, in the framework of linearized quantum gravity, the induced quantum gravitational interaction between two ground-state objects with permanent quadrupole moments, which are subjected to an external gravitational radiation field. Compared with the nonpolar case, there exists an additional term in the leading-order field-induced interobject interaction between two polar objects. This term arises when a real graviton is scattered by the same object center with coupling between the two objects occurring via the exchange of a single virtual graviton, and the interaction is thus relevant to the number density of gravitons, the frequency and polarization of the external gravitational field, as well as the permanent quadrupoles of the objects. Due to the existence of such an additional term, the field-induced quantum gravitational interaction between two polar objects can be significantly different from that between nonpolar ones when the interobject distance is much smaller than the wavelength of the external gravitational radiation field. Although we model the external gravitational radiation as a quantized monochromatic gravitational wave with a certain wave vector and polarization for simplicity, it is possible to generalize to more realistic situations, such as the case of a stochastic background of gravitational radiation.

Interaction potentials, electric moments, polarizabilities, and chemical reactions of YbCu, YbAg, and YbAu molecules

Ultracold YbAg molecules have been recently proposed as promising candidates for electron electric dipole moment searches Verma et al (2020 Phys. Rev. Lett. 125 153201). Here, we calculate potential energy curves, permanent electric dipole and quadrupole moments, and static electric dipole polarizabilities for the YbCu, YbAg, and YbAu molecules in their ground electronic states. We use the coupled cluster method restricted to single, double, and noniterative triple excitations with large Gaussian basis sets, while the scalar relativistic effects are included within the small-core energy-consistent pseudopotentials. We find that the studied molecules are relatively strongly bound with the well depths of 5708 cm−1, 5253 cm−1, and 13349 cm−1 and equilibrium distances of 5.50 bohr, 5.79 bohr, and 5.55 bohr for YbCu, YbAg, and YbAu, respectively. They have large permanent electric dipole moments of 3.2D, 3.3D, and 5.3D at equilibrium distances, respectively. We also calculate equilibrium geometries and energies of corresponding trimers. The studied molecules are chemically reactive unless they are segregated in an optical lattice or shielded with external fields. The investigated molecules may find application in ultracold controlled chemistry, dipolar many-body physics, or precision measurement experiments.

A Few MeV Laser-Plasma Accelerated Proton Beam in Air Collimated Using Compact Permanent Quadrupole Magnets

Proton laser-plasma-based acceleration has nowadays achieved a substantial maturity allowing to seek for possible practical applications, as for example Particle Induced X-ray Emission with few MeV protons. Here we report about the design, implementation, and characterization of a few MeV laser-plasma-accelerated proton beamline in air using a compact and cost-effective beam transport line based on permanent quadrupole magnets. The magnetic beamline coupled with a laser-plasma source based on a 14-TW laser results in a well-collimated proton beam of about 10 mm in diameter propagating in air over a few cm distance.

Quantitative analysis of the electrostatic and electronic polarization energies in molecularly mixed films of organic semiconductors

The energy levels of organic semiconductors are primarily determined by the molecular orbital energies of constituent molecules. Recent studies have, however, shown that the energy levels can be changed by the mixing ratio of two molecules which have different permanent quadrupole moments. From the good correlation between the magnitude of the mixed film's energy shift and the constituent molecules' permanent quadrupole moment, it was noted that the molecular quadrupole plays an important role in the energy shift. In this study, ultraviolet photoelectron spectroscopy (UPS) and low-energy inverse photoemission spectroscopy (LEIPS) are applied to the mixed films of zinc phthalocyanine (ZnPc) and perfluorinated ZnPc (${\mathrm{F}}_{16}\mathrm{ZnPc}$), which have permanent quadrupole moments with opposite directions. From the precisely determined ionization energies and electron affinities, we directly determine the electronic polarization energy $D$ and electrostatic energy $S$ as a function of mixing ratio. Furthermore, we examined the molecular orientation dependence of $S$ and $D$ values. $D$ is almost independent of the mixing ratio (the difference is less than 0.2 eV over the range of mixing ratio) whereas $S$ differs by as much as 1.6 eV. The result clearly shows that the energy levels' continuous shift by the mixing ratio originates in the electrostatic interaction, whose leading term is the charge-permanent quadrupole interaction.

Design, development and characterization of tunable Permanent Magnet Quadrupole for Drift Tube Linac

Bhabha Atomic Research Centre, Trombay is developing LEHIPA (Low Energy High Intensity Proton Accelerator) as pre-injector for 1 GeV proton accelerator for proposed ADSS (Accelerator Driven Sub-critical reactor System). LEHIPA is 20 MeV, 30 mA room temperature accelerator and consists of RFQ (Radio Frequency Quadrupole) and DTL (Drift Tube Linac) as major accelerating structures. The RF (Radio Frequency) design of DT (Drift Tube) of DTL aimed at maximizing the shunt impedance; this demands the size (transverse) of DTs to be minimal. The width of the DT is governed by the β of the particle and trade-off between transit time factor and effective accelerating voltage in the DT gap. The availability of limited volume in DTs for housing magnetic quadrupole has motivated the use of permanent magnets for generating the quadrupole field, as they have high magnetic energy density when compared to conventional electromagnets. With usage of permanent magnets, joule heating is eliminated, this helps in limiting the heat load. DTL has copious microwave heat with heat flux as large as 10 W/cm2 at certain locations. The beam dynamics requires uniformity of integral magnetic field gradient of PMQ (Permanent Magnet Quadrupole) to be better than ±0.5% with nominal value of 2.05 T. Further the drift tubes which houses these PMQs have microwave heat generation on outer surface which ranges from 5 kW to 8 kW depending on the size of the DT. This heat is required to be removed, not doing so would result in resonant frequency detuning in DTL cavity and enhanced temperature would deteriorate the strength of permanent magnets of the PMQ, thereby compromising their focal length. The drift tube has hydraulic circuit for microwave heat removal. This paper describes the magnetic design of the PMQ using Sm2Co17 rare earth permanent magnets. Paper discusses the magnetic design for optimizing integral magnetic field gradient (integral Gdl) uniformity. A novel magnetic field tuning technique is used for tuning the integral magnetic field gradient to required value. Comprehensive magnetic tuning and characterization scheme is presented which relates the measured magnetic moment of the permanent magnets, un-tuned integral Gdl and pole length to the required integral Gdl. Based on this scheme thirty six PMQ embedded drift tubes have been developed. Paper also details the results of characterization of twenty PMQs which forms part of 10 MeV to 15 MeV DTL. The scheme used for tuning integral magnetic field gradient is universal and can be implemented in similar permanent magnets quadrupoles and other permanent magnet based systems.

Orbital period modulation in hot Jupiter systems

ABSTRACT We introduce a model for the orbital period modulation in systems with close-by giant planets based on a spin–orbit coupling that transfers angular momentum from the orbit to the rotation of the planet and vice versa. The coupling is produced by a permanent non-axisymmetric gravitational quadrupole moment assumed to be present in the solid core of the planet. We investigate two regimes of internal planetary rotation, that is, when the planet rotates rigidly and when the rotation of its deep interior is time-dependent as a consequence of a vacillating or intermittent convection in its outer shell. The model is applied to a sample of very hot Jupiters predicting maximum transit-time deviations from a constant-period ephemeris of approximately 50 s in the case of rigid rotation. The transit time variations of WASP-12, currently the only system showing evidence of a non-constant period, cannot be explained by assuming rigid rotation, but can be modelled in the time-dependent internal rotation regime, thus providing an alternative to their interpretation in terms of a tidal decay of the planet orbit.

Design considerations for permanent magnetic quadrupole triplet for matching into laser driven wake field acceleration experiment at SINBAD

The ARES (Accelerator Research experiment at SINBAD) Linac at SINBAD (Short and INnovative Bunches and Accelerators at DESY) facility at DESY aims to produce high brightness ultrashort electron bunches (sub fs to few fs) at around 100 MeV, suitable for injection into novel accelerators e.g. dielectric Laser acceleration (DLA) and Laser Driven Wakefield acceleration (LWFA). The external injection experiment planned at ARES aims for stable LWFA by combining the reproducible conventional RF-based accelerator technology, with high-power plasma wakefield dynamics. The LWFA experiment demands Twiss parameter β to be of the order of few mm, in order to avoid emittance growth because of high accelerating gradient in the plasma. The ARES Linac is capable of producing ultra-short bunches at around 100-150 MeV, so the effect of space charge is significantly high. To match such a space charge dominated beam, strong transverse focusing is required. A Permanent Magnetic Quadrupole (PMQ) triplet is one promising focusing strategy. In this paper, we report the technical design constraints and findings for stable settings for PMQ triplet to match the requirements of the electron beam properties and study of phase spaces for final focus into LWFA experiment.

Evolution of MU69 from a binary planetesimal into contact by Kozai-Lidov oscillations and nebular drag

The New Horizons flyby of the cold classical Kuiper Belt object MU69 showed it to be a contact binary. The existence of other contact binaries in the 1–10 km range raises the question of how common these bodies are and how they evolved into contact. Here we consider that the pre-contact lobes of MU69 formed as a binary embedded in the Solar nebula, and calculate its subsequent orbital evolution in the presence of gas drag. We find that the sub-Keplerian wind of the disk brings the drag timescales for 10 km bodies to under 1 Myr for quadratic-velocity drag, which is valid in the asteroid belt. In the Kuiper belt, however, the drag is linear with velocity and the effect of the wind cancels out as the angular momentum gained in half an orbit is exactly lost in the other half; the drag timescales for 10 km bodies remain ≳10 Myr. In this situation we find that a combination of nebular drag and Kozai-Lidov oscillations is a promising channel for collapse. We analytically solve the hierarchical three-body problem with nebular drag and implement it into a Kozai cycles plus tidal friction model. The permanent quadrupoles of the pre-merger lobes make the Kozai oscillations stochastic, and we find that when gas drag is included the shrinking of the semimajor axis more easily allows the stochastic fluctuations to bring the system into contact. Evolution to contact happens very rapidly (within 104 yr) in the pure, double-average quadrupole, Kozai region between ≈85 − 95∘, and within 3 Myr in the drag-assisted region beyond it. The synergy between J2 and gas drag widens the window of contact to 80∘ − 100∘ initial inclination, over a larger range of semimajor axes than Kozai and J2 alone. As such, the model predicts a low initial occurrence of binaries in the asteroid belt, and an initial contact binary fraction of about 10% for the cold classicals in the Kuiper belt. The speed at contact is the orbital velocity; if contact happens at pericenter at high eccentricity, it deviates from the escape velocity only because of the oblateness, independently of the semimajor axis. For MU69, the oblateness leads to a 30% decrease in contact velocity with respect to the escape velocity, the latter scaling with the square root of the density. For mean densities in the range 0.3–0.5 g cm−3, the contact velocity should be 3.3 − 4.2 m s−1, in line with the observational evidence from the lack of deformation features and estimate of the tensile strength.

COXINEL transport of laser plasma accelerated electrons

Laser plasma acceleration (LPA) enables the generation of an up to several GeV electron beam with a short bunch length and high peak current within a centimeter scale. In view of undulator type light source applications, electron beam manipulation has to be applied. We report here on detailed electron beam transport for an LPA electron beam on the COXINEL test line, that consists of strong permanent quadrupoles to handle the electron beam divergence, a magnetic chicane to reduce the energy spread and a second set of quadrupoles for adjusting the focusing inside the undulator. After describing the measured LPA characteristics, we show that we can properly transport the electron beam along the line, thanks to several screens. We also illustrate the influence of the chromatic effects induced by the electron beam energy spread, both experimentally and numerically. We then study the sensitivity of the transport to the electron beam pointing and skewed quadrupolar components.

A three-point coarse-grained model of five-water cluster with permanent dipoles and quadrupoles.

As coarse-grained (CG) studies of large biomolecules increase, developments of reliable CG solvent models become particularly important. In this work, we reduce five water molecules into a three-point CG model with permanent dipole and quadrupole moments. In the CG force field, the modified Morse potential is utilized and an ideal three-water cluster is designed to derive CG-level permanent multipoles. The new CG model is parametrized on the AMOEBA polarizable force field. Various important properties of liquid water are examined to validate the new CG model. Results show that the new CG model can correctly reproduce certain important experimental properties such as density, isothermal compressibility and relative static dielectric permittivity, even better than the existing AA models. Additionally, the CPU tests reveal that the CG model can accelerate molecular dynamics simulations by a factor of 19 compared to the popular AA force field. Compared with the fix-point-charge model widely used in other CG models, the permanent-multipole-based CG model describes more rigid electrostatic attractions. This study also illustrates that the permanent multipole moments contribute a lot to the electrostatic calculations in CG simulation.

Design and optimization of a laser-PIXE beamline for material science applications

AbstractMulti-MeV proton beams can be generated by irradiating thin solid foils with ultra-intense (>1018 W/cm2) short laser pulses. Several of their characteristics, such as high bunch charge and short pulse duration, make them a complementary alternative to conventional radio frequency-based accelerators. A potential material science application is the chemical analysis of cultural heritage (CH) artifacts. The complete chemistry of the bulk material (ceramics, metals) can be retrieved through sophisticated nuclear techniques such as particle-induced X-ray emission (PIXE). Recently, the use of laser-generated proton beams was introduced as diagnostics in material science (laser-PIXE or laser-driven PIXE): Coupling laser-generated proton sources to conventional beam steering devices successfully enhances the capture and transport of the laser-accelerated beam. This leads to a reduction of the high divergence and broad energy spread at the source. The design of our hybrid beamline is composed of an energy selector, followed by permanent quadrupole magnets aiming for better control and manipulation of the final proton beam parameters. This allows tailoring both, mean proton energy and spot sizes, yet keeping the system compact. We performed a theoretical study optimizing a beamline for laser-PIXE applications. Our design enables monochromatizing the beam and shaping its final spot size. We obtain spot sizes ranging between a fraction of mm up to cm scale at a fraction of nC proton charge per shot. These results pave the way for a versatile and tunable laser-PIXE at a multi-Hz repetition rate using modern commercially available laser systems.