Generation of forerunner electron beam during interaction of ion beam pulse with plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hara, Kentaro; Kaganovich, Igor D.; Startsev, Edward A.

The long-time evolution of the two-stream instability of a cold tenuous ion beam pulse propagating through the background plasma with density much higher than the ion beam density is investigated using a large-scale one-dimensional electrostatic kinetic simulation. The three stages of the instability are investigated in detail. After the initial linear growth and saturation by the electron trapping, a portion of the initially trapped electrons becomes detrapped and moves ahead of the ion beam pulse forming a forerunner electron beam, which causes a secondary two-stream instability that preheats the upstream plasma electrons. Consequently, the self-consistent nonlinear-driven turbulent state is setmore » up at the head of the ion beam pulse with the saturated plasma wave sustained by the influx of the cold electrons from upstream of the beam that lasts until the final stage when the beam ions become trapped by the plasma wave. Finally, the beam ion trapping leads to the nonlinear heating of the beam ions that eventually extinguishes the instability.« less

Impact of centrifugal drifts on ion turbulent transport

DOE Office of Scientific and Technical Information (OSTI.GOV)

Belli, Emily A.; Candy, J.

Here, the influence of sonic toroidal rotation on gyrokinetic stability and transport is studied, with important implications for heavy impurity dynamics. When centrifugal drifts and electrostatic trapping corrections are included, significant modifications to the calculated transport of heavy impurities are observed. These high-rotation corrections add to the standard Coriolis drift and toroidal rotation shear drive which are normally included in gyrokinetics. Yet, because of their complexity, centrifugal and electrostatic trapping terms (quadratic in the main ion Mach number) are not generally included in gyrokinetic codes. In this work, we explore the implications of using reduced descriptions of the rotational physics.more » For heavy impurities such as tungsten, cross terms due to the centrifugal force can dominate the rotation dynamics, and neglecting them is shown to lead to large errors in the impurity particle flux.« less

Impact of centrifugal drifts on ion turbulent transport

DOE PAGES

Belli, Emily A.; Candy, J.

2018-03-01

Here, the influence of sonic toroidal rotation on gyrokinetic stability and transport is studied, with important implications for heavy impurity dynamics. When centrifugal drifts and electrostatic trapping corrections are included, significant modifications to the calculated transport of heavy impurities are observed. These high-rotation corrections add to the standard Coriolis drift and toroidal rotation shear drive which are normally included in gyrokinetics. Yet, because of their complexity, centrifugal and electrostatic trapping terms (quadratic in the main ion Mach number) are not generally included in gyrokinetic codes. In this work, we explore the implications of using reduced descriptions of the rotational physics.more » For heavy impurities such as tungsten, cross terms due to the centrifugal force can dominate the rotation dynamics, and neglecting them is shown to lead to large errors in the impurity particle flux.« less

Impact of Shock Front Rippling and Self-reformation on the Electron Dynamics at Low-Mach-number Shocks

NASA Astrophysics Data System (ADS)

Yang, Zhongwei; Lu, Quanming; Liu, Ying D.; Wang, Rui

2018-04-01

Electron dynamics at low-Mach-number collisionless shocks are investigated by using two-dimensional electromagnetic particle-in-cell simulations with various shock normal angles. We found: (1) The reflected ions and incident electrons at the shock front provide an effective mechanism for the quasi-electrostatic wave generation due to the charge-separation. A fraction of incident electrons can be effectively trapped and accelerated at the leading edge of the shock foot. (2) At quasi-perpendicular shocks, the electron trapping and reflection is nonuniform due to the shock rippling along the shock surface and is more likely to take place at some locations accompanied by intense reflected ion-beams. The electron trapping process has a periodical evolution over time due to the shock front self-reformation, which is controlled by ion dynamics. Thus, this is a cross-scale coupling phenomenon. (3) At quasi-parallel shocks, reflected ions can travel far back upstream. Consequently, quasi-electrostatic waves can be excited in the shock transition and the foreshock region. The electron trajectory analysis shows these waves can trap electrons at the foot region and reflect a fraction of them far back upstream. Simulation runs in this paper indicate that the micro-turbulence at the shock foot can provide a possible scenario for producing the reflected electron beam, which is a basic condition for the type II radio burst emission at low-Mach-number interplanetary shocks driven by Coronal Mass Ejections (CMEs).

Utility of Higher Harmonics in Electrospray Ionization Fourier Transform Electrostatic Linear Ion Trap Mass Spectrometry.

PubMed

Dziekonski, Eric T; Johnson, Joshua T; McLuckey, Scott A

2017-04-18

Mass resolution (M/ΔM fwhm) is observed to linearly increase with harmonic order in a Fourier transform electrostatic linear ion trap (ELIT) mass spectrometer. This behavior was predicted by Grosshans and Marshall for frequency-multiple detection in a Fourier transform ion cyclotron resonance mass spectrometer only for situations when the prominent mechanism for signal decay is ion ejection from the trap. As the analyzer pressure in our ELIT chamber is relatively high, such that collisional scattering and collision-induced dissociation are expected to underlie much of the ion loss, we sought to explore the relationship between harmonic order and mass resolution. Mass resolutions of 36 900 (fundamental), 75 850 (2nd harmonic), and 108 200 (3rd harmonic) were obtained for GdO + (avg. m/z 173.919) with a transient length of 300 ms. To demonstrate that the mass resolution was truly increasing with harmonic order, the unresolved isotopes at the fundamental distribution of cytochrome c +8 (m/z ∼ 1549) were nearly baseline, resolved at the third harmonic (mass resolution ≈ 23 000) with a transient length of only 200 ms. This experiment demonstrates that, when the ion density is sufficiently low, ions with frequency differences of less than 4 Hz remain uncoalesced. Higher harmonics can be used to increase the effective mass resolution for a fixed transient length and thereby may enable the resolution of closely spaced masses, determination of a protein ion's charge state, and study of the onset of peak coalescence when the resolution at the fundamental frequency is insufficient.

The new ClusterTrap setup

NASA Astrophysics Data System (ADS)

Martinez, F.; Marx, G.; Schweikhard, L.; Vass, A.; Ziegler, F.

2011-07-01

ClusterTrap has been designed to investigate properties of atomic clusters in the gas phase with particular emphasis on the dependence on the cluster size and charge state. The combination of cluster source, Penning trap and time-of-flight mass spectrometry allows a variety of experimental schemes including collision-induced dissociation, photo-dissociation, further ionization by electron impact, and electron attachment. Due to the storage capability of the trap extended-delay reaction experiments can be performed. Several recent modifications have resulted in an improved setup. In particular, an electrostatic quadrupole deflector allows the coupling of several sources or detectors to the Penning trap. Furthermore, a linear radio-frequency quadrupole trap has been added for accumulation and ion bunching and by switching the potential of a drift tube the kinetic energy of the cluster ions can be adjusted on their way towards or from the Penning trap. Recently, experiments on multiply negatively charged clusters have been resumed.

Effect of Trapped Ions on Shielding and Floating Potential of a Dust Grain in a Plasma

NASA Astrophysics Data System (ADS)

Lampe, Martin; Ganguli, Gurudas; Joyce, Glenn; Gavrishchaka, Valeriy

2001-10-01

The problem of electrostatic shielding around a small spherical collector immersed in plasma, and the related problem of electron and ion flow to the collector, date to the origins of plasma physics. Beginning with Mott-Smith and Langmuir (1926), calculations have typically neglected collisions, on the grounds that the mean free path is long compared to shielding length scales, i.e. the Debye length. However, investigators beginning with Bernstein and Rabinowitz (1959) have known that negative-energy trapped ions, created by occasional collisions, might be important. We present an analytic calculation of the density of trapped and untrapped ions, self-consistent with the potential. Under typical conditions for dust grains immersed in a discharge plasma, trapped ions dominate the shielding cloud in steady state, even in the limit of very long mean free path. As a result the shielded potential is different from the results of orbital motion limited theory. Collisions also greatly increase the ion current to the collector, thereby decreasing the floating potential and the grain charge by a factor as large as two to three.

ELISA - an electrostatic storage ring for low-energy ions

NASA Astrophysics Data System (ADS)

Pape Moeller, Soeren

1997-05-01

The design of a new type of storage ring for low-energy ions using electrostatic deflection and focusing devices is described. Electrostatic bends and quadrupoles are used since they are more efficient than magnetic ones for low-velocity heavy ions. Furthermore, electrostatic devices are more compact and easier to construct than magnetic devices. In comparison to an electromagnetic trap, one important advantage of the elecrostatic ring is the easy access to the circulating beam and its decay products. These and other features, e.g. no magnetic fields, makes such storage devices attractive for many atomic-physics experiments. Also neigboring fields as chemistry and biology might benefit from such an relatively inexpensive device. One important difference between an electrostatic and a magnetic ring is, that the longitudinal energy is not conserved for the electrostatic ring. The actual ring will have a race-track shape as defined by two straight sections each with two quadrupole doublets connected by 180-degrees bends. The bends will consist of 160-degrees spherical deflection plates surrounded by two parallel plate 10-degrees bends. The storage ring ELISA, currently being built, will have a circumference of 6 meters. The first beam tests will take place during summer 1996.

Bloch equations applied to ion cyclotron resonance spectroscopy: Broadband interconversion between magnetron and cyclotron motion for ion axialization

NASA Astrophysics Data System (ADS)

Guan, Shenheng; Marshall, Alan G.

1993-03-01

Conversion of magnetron motion to cyclotron motion combined with collisional cooling of the cyclotron motion provides an efficient way to reduce the kinetic energy of trapped heavy ions and to reduce their magnetron radii in an ion cyclotron resonance (ICR) ion trap. The coupling of magnetron and cyclotron motion can be realized by azimuthal quadrupolar excitation. Theoretical understanding of the coupling process has until now been based on resonant single-frequency quadrupolar excitation at the combination frequency ωc=ω++ω-, in which ωc is the ion cyclotron orbital frequency in the absence of electrostatic field; and ω+ and ω- are the reduced cyclotron and magnetron frequencies in the presence of an electrostatic trapping potential. In this work, we prove that the magnetron/cyclotron coupling is closely related to a two energy level system whose behavior is described by the well-known Bloch equations. By means of a special transformation, the equations of motion for the coupling may be expressed in Bloch-type equations in spherical coordinates. We show that magnetron-to-cyclotron conversion by single-frequency quadrupolar excitation in ICR is analogous to a 180° pulse in nuclear magnetic resonance (NMR). We go on to show that simultaneous magnetron-to-cyclotron conversion of ions over a finite mass-to-charge ratio range may be produced by quadrupolar frequency-sweep excitation, by analogy to adiabatic rapid passage in magnetic resonance. Axialization by broadband magnetron-to-cyclotron conversion followed by cyclotron cooling is successfully demonstrated experimentally for a crude oil distillate sample.

Determining Energies and Cross Sections of Individual Ions Using Higher-Order Harmonics in Fourier Transform Charge Detection Mass Spectrometry (FT-CDMS)

NASA Astrophysics Data System (ADS)

Harper, Conner C.; Elliott, Andrew G.; Lin, Haw-Wei; Williams, Evan R.

2018-06-01

A general method for in situ measurements of the energy of individual ions trapped and weighed using charge detection mass spectrometry (CDMS) is described. Highly charged (> 300 e), individual polyethylene glycol (PEG) ions are trapped and oscillate within an electrostatic trap, producing a time domain signal. A segmented Fourier transform (FT) of this signal yields the temporal evolution of the fundamental and harmonic frequencies of ion motion throughout the 500-ms trap time. The ratio of the fundamental frequency and second harmonic (HAR) depends on the ion energy, which is an essential parameter for measuring ion mass in CDMS. This relationship is calibrated using simulated ion signals, and the calibration is compared to the HAR values measured for PEG ion signals where the ion energy was also determined using an independent method that requires that the ions be highly charged (> 300 e). The mean error of 0.6% between the two measurements indicates that the HAR method is an accurate means of ion energy determination that does not depend on ion size or charge. The HAR is determined dynamically over the entire trapping period, making it possible to observe the change in ion energy that takes place as solvent evaporates from the ion and collisions with background gas occur. This method makes it possible to measure mass changes, either from solvent evaporation or from molecular fragmentation (MSn), as well as the cross sections of ions measured using CDMS.

Effect of particles attachment to multi-sized dust grains present in electrostatic sheaths of discharge plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zaham, B.; Faculté des Sciences et des Sciences Appliquées, Université de Bouira Rue Drissi Yahia 10000 Bouira; Tahraoui, A., E-mail: alatif-tahraoui@yahoo.fr

The loss of electrons and ions due to their attachment to a Gauss-distributed sizes of dust grains present in electrostatic sheaths of discharge plasmas is investigated. A uni-dimensional, unmagnetized, and stationary multi-fluid model is proposed. Forces acting on the dust grain along with its charge are self-consistently calculated, within the limits of the orbit motion limited model. The dynamic analysis of dust grains shows that the contribution of the neutral drag force in the net force acting on the dust grain is negligible, whereas the contribution of the gravity force is found considerable only for micrometer particles. The dust grainsmore » trapping is only possible when the electrostatic force is balanced by the ion drag and the gravity forces. This trapping occurs for a limited radius interval of micrometer dust grains, which is around the most probable dust grain radius. The effect of electron temperature and ion density at the sheath edge is also discussed. It is shown that the attachment of particles reduces considerably the sheath thickness and induces dust grain deceleration. The increase of the lower limit as well as the upper limit of the dust radius reduces also the sheath thickness.« less

In-depth study of in-trap high-resolution mass separation by transversal ion ejection from a multi-reflection time-of-flight device.

PubMed

Fischer, Paul; Knauer, Stefan; Marx, Gerrit; Schweikhard, Lutz

2018-01-01

The recently introduced method of ion separation by transversal ejection of unwanted species in electrostatic ion-beam traps and multi-reflection time-of-flight devices has been further studied in detail. As this separation is performed during the ion storage itself, there is no need for additional external devices such as ion gates or traps for either pre- or postselection of the ions of interest. The ejection of unwanted contaminant ions is performed by appropriate pulses of the potentials of deflector electrodes. These segmented ring electrodes are located off-center in the trap, i.e., between one of the two ion mirrors and the central drift tube, which also serves as a potential lift for capturing incoming ions and axially ejecting ions of interest after their selection. The various parameters affecting the selection effectivity and resolving power are illustrated with tin-cluster measurements, where isotopologue ion species provide mass differences down to a single atomic mass unit at ion masses of several hundred. Symmetric deflection voltages of only 10 V were found sufficient for the transversal ejection of ion species with as few as three deflection pulses. The duty cycle, i.e., the pulse duration with respect to the period of ion revolution, has been varied, resulting in resolving powers of up to several tens of thousands for this selection technique.

In-depth study of in-trap high-resolution mass separation by transversal ion ejection from a multi-reflection time-of-flight device

NASA Astrophysics Data System (ADS)

Fischer, Paul; Knauer, Stefan; Marx, Gerrit; Schweikhard, Lutz

2018-01-01

The recently introduced method of ion separation by transversal ejection of unwanted species in electrostatic ion-beam traps and multi-reflection time-of-flight devices has been further studied in detail. As this separation is performed during the ion storage itself, there is no need for additional external devices such as ion gates or traps for either pre- or postselection of the ions of interest. The ejection of unwanted contaminant ions is performed by appropriate pulses of the potentials of deflector electrodes. These segmented ring electrodes are located off-center in the trap, i.e., between one of the two ion mirrors and the central drift tube, which also serves as a potential lift for capturing incoming ions and axially ejecting ions of interest after their selection. The various parameters affecting the selection effectivity and resolving power are illustrated with tin-cluster measurements, where isotopologue ion species provide mass differences down to a single atomic mass unit at ion masses of several hundred. Symmetric deflection voltages of only 10 V were found sufficient for the transversal ejection of ion species with as few as three deflection pulses. The duty cycle, i.e., the pulse duration with respect to the period of ion revolution, has been varied, resulting in resolving powers of up to several tens of thousands for this selection technique.

Effect of Trapped Ions on Shielding of a Charged Spherical Object in a Plasma

NASA Astrophysics Data System (ADS)

Lampe, Martin; Ganguli, Gurudas; Joyce, Glenn; Gavrishchaka, Valeriy

2001-04-01

The problem of electrostatic shielding around a small spherical collector immersed in plasma, and the related problem of electron and ion flow to the collector, date to the origins of plasma physics. Beginning with Langmuir[1], all calculations have neglected collisions, on the grounds that the mean free path is long compared to shielding length scales, i.e. the Debye length. However, investigators beginning with Bernstein and Rabinowitz[2] have known that negative-energy trapped ions, created by occasional collisions, might be important. We present an analytic calculation of the density of trapped and untrapped ions, self-consistent with a calculation of the potential. We show that under typical conditions for dust grains immersed in a discharge plasma, trapped ions dominate the shielding cloud in steady state, even in the limit of very long mean free path. As a result the shielded potential is quite different from the Debye form or the results of orbital motion limited theory. Collisions also modify the ion current to the grain, but to a lesser extent. [1]H. Mott-Smith and I. Langmuir, Phys. Rev. 28, 27 (1926). [2]I. Bernstein and I. Rabinowitz, Phys. Fluids 2,112(1959).

Determining Energies and Cross Sections of Individual Ions Using Higher-Order Harmonics in Fourier Transform Charge Detection Mass Spectrometry (FT-CDMS).

PubMed

Harper, Conner C; Elliott, Andrew G; Lin, Haw-Wei; Williams, Evan R

2018-06-02

A general method for in situ measurements of the energy of individual ions trapped and weighed using charge detection mass spectrometry (CDMS) is described. Highly charged (> 300 e), individual polyethylene glycol (PEG) ions are trapped and oscillate within an electrostatic trap, producing a time domain signal. A segmented Fourier transform (FT) of this signal yields the temporal evolution of the fundamental and harmonic frequencies of ion motion throughout the 500-ms trap time. The ratio of the fundamental frequency and second harmonic (HAR) depends on the ion energy, which is an essential parameter for measuring ion mass in CDMS. This relationship is calibrated using simulated ion signals, and the calibration is compared to the HAR values measured for PEG ion signals where the ion energy was also determined using an independent method that requires that the ions be highly charged (> 300 e). The mean error of 0.6% between the two measurements indicates that the HAR method is an accurate means of ion energy determination that does not depend on ion size or charge. The HAR is determined dynamically over the entire trapping period, making it possible to observe the change in ion energy that takes place as solvent evaporates from the ion and collisions with background gas occur. This method makes it possible to measure mass changes, either from solvent evaporation or from molecular fragmentation (MS n ), as well as the cross sections of ions measured using CDMS. Graphical Abstract.

Simulation and optimization of a 10 A electron gun with electrostatic compression for the electron beam ion source.

PubMed

Pikin, A; Beebe, E N; Raparia, D

2013-03-01

Increasing the current density of the electron beam in the ion trap of the Electron Beam Ion Source (EBIS) in BNL's Relativistic Heavy Ion Collider facility would confer several essential benefits. They include increasing the ions' charge states, and therefore, the ions' energy out of the Booster for NASA applications, reducing the influx of residual ions in the ion trap, lowering the average power load on the electron collector, and possibly also reducing the emittance of the extracted ion beam. Here, we discuss our findings from a computer simulation of an electron gun with electrostatic compression for electron current up to 10 A that can deliver a high-current-density electron beam for EBIS. The magnetic field in the cathode-anode gap is formed with a magnetic shield surrounding the gun electrodes and the residual magnetic field on the cathode is (5 ÷ 6) Gs. It was demonstrated that for optimized gun geometry within the electron beam current range of (0.5 ÷ 10) A the amplitude of radial beam oscillations can be maintained close to 4% of the beam radius by adjusting the injection magnetic field generated by a separate magnetic coil. Simulating the performance of the gun by varying geometrical parameters indicated that the original gun model is close to optimum and the requirements to the precision of positioning the gun elements can be easily met with conventional technology.

Simulation and optimization of a 10 A electron gun with electrostatic compression for the electron beam ion source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pikin, A.; Beebe, E. N.; Raparia, D.

Increasing the current density of the electron beam in the ion trap of the Electron Beam Ion Source (EBIS) in BNL's Relativistic Heavy Ion Collider facility would confer several essential benefits. They include increasing the ions' charge states, and therefore, the ions' energy out of the Booster for NASA applications, reducing the influx of residual ions in the ion trap, lowering the average power load on the electron collector, and possibly also reducing the emittance of the extracted ion beam. Here, we discuss our findings from a computer simulation of an electron gun with electrostatic compression for electron current upmore » to 10 A that can deliver a high-current-density electron beam for EBIS. The magnetic field in the cathode-anode gap is formed with a magnetic shield surrounding the gun electrodes and the residual magnetic field on the cathode is (5 Division-Sign 6) Gs. It was demonstrated that for optimized gun geometry within the electron beam current range of (0.5 Division-Sign 10) A the amplitude of radial beam oscillations can be maintained close to 4% of the beam radius by adjusting the injection magnetic field generated by a separate magnetic coil. Simulating the performance of the gun by varying geometrical parameters indicated that the original gun model is close to optimum and the requirements to the precision of positioning the gun elements can be easily met with conventional technology.« less

Dendritic polyelectrolytes as seen by the Poisson-Boltzmann-Flory theory.

PubMed

Kłos, J S; Milewski, J

2018-06-20

G3-G9 dendritic polyelectrolytes accompanied by counterions are investigated using the Poisson-Boltzmann-Flory theory. Within this approach we solve numerically the Poisson-Boltzmann equation for the mean electrostatic potential and minimize the Poisson-Boltzmann-Flory free energy with respect to the size of the molecules. Such a scheme enables us to inspect the conformational and electrostatic properties of the dendrimers in equilibrium based on their response to varying the dendrimer generation. The calculations indicate that the G3-G6 dendrimers exist in the polyelectrolyte regime where absorption of counterions into the volume of the molecules is minor. Trapping of ions in the interior region becomes significant for the G7-G9 dendrimers and signals the emergence of the osmotic regime. We find that the behavior of the dendritic polyelectrolytes corresponds with the degree of ion trapping. In particular, in both regimes the polyelectrolytes are swollen as compared to their neutral counterparts and the expansion factor is maximal at the crossover generation G7.

Ion Dynamic Capture Experiments With The High Performance Antiproton Trap (HiPAT)

NASA Technical Reports Server (NTRS)

Martin, James; Lewis, Raymond; Chakrabarti, Suman; Sims, William H.; Pearson, J. Boise; Fant, Wallace E.

2002-01-01

To take the first step towards using the energy produced from the matter-antimatter annihilation for propulsion applications, the NASA Marshall Space Flight Center (MSFC) Propulsion Research Center (PRC) has initiated a research activity examining the storage of low energy antiprotons. The High Performance Antiproton Trap (HiPAT) is an electromagnetic system (Penning-Malmberg design) consisting of a 4 Tesla superconductor, a high voltage electrode confinement system, and an ultra high vacuum test section. It has been designed with an ultimate goal of maintaining 10(exp 12) charged particles with a half-life of 18 days. Currently, this system is being evaluated experimentally using normal matter ions that are cheap to produce, relatively easy to handle, and provide a good indication of overall trap behavior (with the exception of assessing annihilation losses). The ions are produced via a positive hydrogen ion source and transported to HiPAT in a beam line equipped with electrostatic optics. The optics serve to both focus and gate the incoming ions, providing microsecond-timed beam pulses that are dynamically captured by cycling the HiPAT forward containment field like a "trap door". Initial dynamic capture experiments have been successfully performed with beam energy and currents set to 1.9 kV and 23 micro-amps, respectively. At these settings up to 2x10(exp 9) ions have been trapped during a single dynamic cycle.

Selective passive adsorption of nitrate with surfactant treated porous electrode and electrostatic regeneration

NASA Astrophysics Data System (ADS)

Oyarzun, Diego I.; Hemmatifar, Ali; Palko, James W.; Stadermann, Michael; Santiago, Juan G.; Stanford microfluidics lab Team; Lawrence Livermore National Lab Team

2017-11-01

Nitrate is an important pollutant in drinking water worldwide, and a number of methods exist for the removal of nitrate from water including ion exchange and reverse osmosis. However, these approaches suffer from a variety of disadvantages including the need for a regenerating brine supply and disposal of used brine for ion exchange and low water recovery ratio for reverse osmosis. We are researching and developing a form of capacitive deionization (CDI) for energy efficient desalination and selective removal of ionic toxins from water. In CDI an electrode is used to electrostatically trap ions in a pair of porous electrodes. Here, we demonstrate the use of high surface area activated carbon electrodes functionalized with ion exchange moieties for adsorption of nitrate from aqueous solution. Unlike a traditional ion exchanger, the functionalized surfaces can be repeatedly regenerated by the application of an electrostatic potential which displaces the bound NO3- while leaving an excess of electronic charge on the electrode. Trimethylammonium has an intrinsic selectivity, we are using this moiety to selectively remove nitrate over chloride. We performed adsorption/desorption cycles under several desorption voltages and ratios of concentrations.

Energy gain calculations in Penning fusion systems using a bounce-averaged Fokker-Planck model

NASA Astrophysics Data System (ADS)

Chacón, L.; Miley, G. H.; Barnes, D. C.; Knoll, D. A.

2000-11-01

In spherical Penning fusion devices, a spherical cloud of electrons, confined in a Penning-like trap, creates the ion-confining electrostatic well. Fusion energy gains for these systems have been calculated in optimistic conditions (i.e., spherically uniform electrostatic well, no collisional ion-electron interactions, single ion species) using a bounce-averaged Fokker-Planck (BAFP) model. Results show that steady-state distributions in which the Maxwellian ion population is dominant correspond to lowest ion recirculation powers (and hence highest fusion energy gains). It is also shown that realistic parabolic-like wells result in better energy gains than square wells, particularly at large well depths (>100 kV). Operating regimes with fusion power to ion input power ratios (Q-value) >100 have been identified. The effect of electron losses on the Q-value has been addressed heuristically using a semianalytic model, indicating that large Q-values are still possible provided that electron particle losses are kept small and well depths are large.

Transfer matrix calculation for ion optical elements using real fields

NASA Astrophysics Data System (ADS)

Mishra, P. M.; Blaum, K.; George, S.; Grieser, M.; Wolf, A.

2018-03-01

With the increasing importance of ion storage rings and traps in low energy physics experiments, an efficient transport of ion species from the ion source area to the experimental setup becomes essential. Some available, powerful software packages rely on transfer matrix calculations in order to compute the ion trajectory through the ion-optical beamline systems of high complexity. With analytical approaches, so far the transfer matrices are documented only for a few ideal ion optical elements. Here we describe an approach (using beam tracking calculations) to determine the transfer matrix for any individual electrostatic or magnetostatic ion optical element. We verify the procedure by considering the well-known cases and then apply it to derive the transfer matrix of a 90-degree electrostatic quadrupole deflector including its realistic geometry and fringe fields. A transfer line consisting of a quadrupole deflector and a quadrupole doublet is considered, where the results from the standard first order transfer matrix based ion optical simulation program implementing the derived transfer matrix is compared with the real field beam tracking simulations.

ITG-TEM turbulence simulation with bounce-averaged kinetic electrons in tokamak geometry

NASA Astrophysics Data System (ADS)

Kwon, Jae-Min; Qi, Lei; Yi, S.; Hahm, T. S.

2017-06-01

We develop a novel numerical scheme to simulate electrostatic turbulence with kinetic electron responses in magnetically confined toroidal plasmas. Focusing on ion gyro-radius scale turbulences with slower frequencies than the time scales for electron parallel motions, we employ and adapt the bounce-averaged kinetic equation to model trapped electrons for nonlinear turbulence simulation with Coulomb collisions. Ions are modeled by employing the gyrokinetic equation. The newly developed scheme is implemented on a global δf particle in cell code gKPSP. By performing linear and nonlinear simulations, it is demonstrated that the new scheme can reproduce key physical properties of Ion Temperature Gradient (ITG) and Trapped Electron Mode (TEM) instabilities, and resulting turbulent transport. The overall computational cost of kinetic electrons using this novel scheme is limited to 200%-300% of the cost for simulations with adiabatic electrons. Therefore the new scheme allows us to perform kinetic simulations with trapped electrons very efficiently in magnetized plasmas.

A Single-Ion Reservoir as a High-Sensitive Sensor of Electric Signals.

PubMed

Domínguez, Francisco; Arrazola, Iñigo; Doménech, Jaime; Pedernales, Julen S; Lamata, Lucas; Solano, Enrique; Rodríguez, Daniel

2017-08-21

A single-ion reservoir has been tested, and characterized in order to be used as a highly sensitive optical detector of electric signals arriving at the trapping electrodes. Our system consists of a single laser-cooled 40 Ca + ion stored in a Paul trap with rotational symmetry. The performance is observed through the axial motion of the ion, which is equivalent to an underdamped and forced oscillator. Thus, the results can be projected also to Penning traps. We have found that, for an ion oscillator temperature T axial  ≲ 10 mK in the forced-frequency range ω z  = 2π × (80,200 kHz), the reservoir is sensitive to a time-varying electric field equivalent to an electric force of 5.3(2) neV/μm, for a measured quality factor Q = 3875(45), and a decay time constant γ z  = 88(2) s -1 . This method can be applied to measure optically the strength of an oscillating field or induced (driven) charge in this frequency range within times of tens of milliseconds. Furthermore the ion reservoir has been proven to be sensitive to electrostatic forces by measuring the ion displacement. Since the heating rate is below 0.3 μeV/s, this reservoir might be used as optical detector for any ion or bunch of charged particles stored in an adjacent trap.

Planetary plasma waves

NASA Technical Reports Server (NTRS)

Gurnett, Donald A.

1993-01-01

The primary types of plasma waves observed in the vicinity of the planets Venus, Mars, Earth, Jupiter, Saturn, Uranus, and Neptune are described. The observations are organized according to the various types of plasma waves observed, ordered according to decreasing distance from the planet, starting from the sunward side of the planet, and ending in the region near the closest approach. The plasma waves observed include: electron plasma oscillations and ion acoustic waves; trapped continuum radiation; electron cyclotron and upper hybrid waves; whistler-mode emissions; electrostatic ion cyclotron waves; and electromagnetic ion cyclotron waves.

Analytic model of a laser-accelerated composite plasma target and its stability

NASA Astrophysics Data System (ADS)

Khudik, Vladimir; Shvets, Gennady

2013-10-01

A self-consistent analytical model of monoenergetic acceleration of a one and two-species ultrathin target irradiated by a circularly polarized laser pulse is developed. In the accelerated reference frame, the bulk plasma in the target is neutral and its parameters are assumed to be stationary. It is found that the structure of the target depends strongly on the temperatures of electrons and ions, which are both strongly influenced by the laser pulse pedestal. When the electron temperature is large, the hot electrons bounce back and forth inside the potential well formed by ponderomotive and electrostatic potentials while the heavy and light ions are forced-balanced by the electrostatic and non-inertial fields forming two separated layers. In the opposite limiting case when the ion temperature is large, the hot ions are trapped in the potential well formed by the ion-sheath's electric and non-inertial potentials while the cold electrons are forced-balanced by the electrostatic and ponderomotive fields. Using PIC simulations we have determined which scenario is realized in practice depending on the initial target structure and laser intensity. Target stability with respect to Rayleigh-Taylor instability will also be discussed. This work is supported by the US DOE grants DE-FG02-04ER41321 and DE-FG02-07ER54945.

Ion related problems for the XLS ring

NASA Astrophysics Data System (ADS)

Bozoki, Eva S.; Halama, Henry

1991-10-01

The electron beam in a storage ring collides with the residual gas in the vacuum chamber. As a consequence, low velocity positive ions are produced and trapped in the potential well of the electron beam. They perform stable or unstable oscillations around the beam under the repetitive Coulomb force of the bunches. If not cleared, the captured ions can lead to partial or total neutralization of the beam, causing both a decrease of lifetime and a change in the vertical tunes as well as an increase in the tune spread. It can also cause coherent and incoherent transverse instabilities. An electrostatic clearing electrodes system was designed to keep the neutralization below a desired limit. The location and the geometry of the clearing electrodes as well as the applied clearing voltage is based on the study of the ion production rate, longitudinal velocity of ions in field-free regions and in the dipoles, beam self-electric field, beam potential, critical mass for ion capture in the bunched beam and the bounce frequencies of the ions, tune shift and pressure rise due to trapped ions.

Ion-mobility study of two functionalized pentacene structural isomers using a modified electrospray/triple quadrupole mass spectrometer

NASA Astrophysics Data System (ADS)

Prada, Svitlana V.; Bohme, Diethard K.; Baranov, Vladimir I.

2007-03-01

We report ion-mobility measurements with a modified triple quadrupole mass spectrometer fitted with an ion molecule reactor (IMR) designed to investigate ion molecule reactivity in organic mass spectrometry. Functionalized pentacene ions, which are generally unreactive were chosen for study to decouple drift/diffusion effects from reactivity (including clustering). The IMR is equipped with a variable axial electrostatic drift field (ADF) and is able to trap ions. These capabilities were successfully employed in the measurement of ion mobilities in different modes of IMR operation. Theoretical modeling of the drift dynamics and the special localization of the large ion packet was successfully implemented. The contribution of the quadrupole RF field to the drift dynamics also was taken into consideration.

Inertial electrostatic confinement and nuclear fusion in the interelectrode plasma of a nanosecond vacuum discharge. I: Experiment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kurilenkov, Yu. K.; Skowronek, M.

2010-12-15

Properties of an aerosol substance with a high power density in the interelectrode space of a nano- second vacuum discharge are studied. The possibilities of emission and/or trapping of fast ions and hard X-rays by ensembles of clusters and microparticles are analyzed. The possibility of simultaneous partial trapping (diffusion) of X-rays and complete trapping of fast ions by a cluster ensemble is demonstrated experimentally. Due to such trapping, the aerosol ensemble transforms into a 'dusty' microreactor that can be used to investigate a certain class of nuclear processes, including collisional DD microfusion. Operating regimes of such a microreactor and theirmore » reproducibility were studied. On the whole, the generation efficiency of hard X-rays and neutrons in the proposed vacuum discharge with a hollow cathode can be higher by two orders of magnitude than that in a system 'high-power laser pulse-cluster cloud.' Multiply repeated nuclear fusion accompanied by pulsating DD neutron emission was reproducibly detected in experiment. Ion acceleration mechanisms in the interelectrode space and the fundamental role of the virtual cathode in observed nuclear fusion processes are discussed.« less

Manufacturing a thin wire electrostatic trap for ultracold polar molecules.

PubMed

Kleinert, J; Haimberger, C; Zabawa, P J; Bigelow, N P

2007-11-01

We present a detailed description on how to build a thin wire electrostatic trap (TWIST) for ultracold polar molecules. It is the first design of an electrostatic trap that can be superimposed directly onto a magneto-optical trap (MOT). We can thus continuously produce ultracold polar molecules via photoassociation from a two species MOT and instantaneously trap them in the TWIST without the need for complex transfer schemes. Despite the spatial overlap of the TWIST and the MOT, the two traps can be operated and optimized completely independently due to the complementary nature of the utilized trapping mechanisms.

Vertical sizes of 1-D and 2-D electrostatic solitons with nonextensive and trapped electrons in the upper ionosphere

NASA Astrophysics Data System (ADS)

Ali Shan, Shaukat; Saleem, Hamid

2018-05-01

The vertical sizes of one-dimensional (1-D) and two dimensional (2-D) electrostatic solitons are estimated in the oxygen-hydrogen (O - H) and pure oxygen plasmas of the upper ionosphere taking into account the effects of non-extensive and trapped electrons. The field-aligned flow of oxygen ions is also considered. It is found that both electron trapping and non-extensivity play a constructive role in the formation of 1-D and 2-D solitary structures. The vertical size of the solitons is not known through observations, but here it is pointed out that the vertical size of these structures should be of the order of a few meters at the altitude of 800 km in the 1-D case. On the other hand, in the 2-D case, the vertical size is much larger than the horizontal size and it turns out to be of the order of a few kilometers, while the width is about a few hundred meters in agreement with the observations.

Calibration function for the Orbitrap FTMS accounting for the space charge effect.

PubMed

Gorshkov, Mikhail V; Good, David M; Lyutvinskiy, Yaroslav; Yang, Hongqian; Zubarev, Roman A

2010-11-01

Ion storage in an electrostatic trap has been implemented with the introduction of the Orbitrap Fourier transform mass spectrometer (FTMS), which demonstrates performance similar to high-field ion cyclotron resonance MS. High mass spectral characteristics resulted in rapid acceptance of the Orbitrap FTMS for Life Sciences applications. The basics of Orbitrap operation are well documented; however, like in any ion trap MS technology, its performance is limited by interactions between the ion clouds. These interactions result in ion cloud couplings, systematic errors in measured masses, interference between ion clouds of different size yet with close m/z ratios, etc. In this work, we have characterized the space-charge effect on the measured frequency for the Orbitrap FTMS, looking for the possibility to achieve sub-ppm levels of mass measurement accuracy (MMA) for peptides in a wide range of total ion population. As a result of this characterization, we proposed an m/z calibration law for the Orbitrap FTMS that accounts for the total ion population present in the trap during a data acquisition event. Using this law, we were able to achieve a zero-space charge MMA limit of 80 ppb for the commercial Orbitrap FTMS system and sub-ppm level of MMA over a wide range of total ion populations with the automatic gain control values varying from 10 to 10(7). Copyright © 2010 American Society for Mass Spectrometry. Published by Elsevier Inc. All rights reserved.

Energy gain calculations in spherical IEC fusion systems using the BAFP code

NASA Astrophysics Data System (ADS)

Chacón, L.; Miley, G. H.; Barnes, D. C.; Knoll, D. A.

1999-11-01

The spherical IEC fusion concept takes advantage of the potential well generated by an inner spherical cathode (physical or virtual), biased negatively to several kV with respect to a concentric outer grounded boundary, to focus ions inwards and form a dense central core where fusion may occur. However, defocusing of the ion beams due to ion-ion collisions may prevent a satisfactory energy balance in the system. This research concentrates of spherically symmetric virtual cathode IEC devices, in which a spherical cloud of electrons, confined á la Penning trap, creates the ion-confining electrostatic well. A bounce-averaged Fokker-Planck model has been constructed to analyze the ion physics in ideal conditions (i.e., spherically uniform electrostatic well, no collisional interaction between ions and electrons, single ion species).(L. Chacon, D. C. Barnes, D. A. Knoll, 40^th) Annual Meeting of the APS Division of Plasma Physics, New Orleans, LA, Nov. 1998 Results will reproduce the phenomenology of previously published( W. Nevins, Phys. Plasmas), 2(10), 3804-3819 (1995) theoretical limits, and will show that, under some conditions, steady-state solutions with relatively high gains and small ion recirculation powers exist for the bounce-averaged Fokker-Planck transport equation. Variations in gain with parameter space will be presented.

A versatile electrostatic trap with open optical access

NASA Astrophysics Data System (ADS)

Li, Sheng-Qiang; Yin, Jian-Ping

2018-04-01

A versatile electrostatic trap with open optical access for cold polar molecules in weak-field-seeking state is proposed in this paper. The trap is composed of a pair of disk electrodes and a hexapole. With the help of a finite element software, the spatial distribution of the electrostatic field is calculated. The results indicate that a three-dimensional closed electrostatic trap is formed. Taking ND3 molecules as an example, the dynamic process of loading and trapping is simulated. The results show that when the velocity of the molecular beam is 10 m/s and the loading time is 0.9964 ms, the maximum loading efficiency reaches 94.25% and the temperature of the trapped molecules reaches about 30.3 mK. A single well can be split into two wells, which is of significant importance to the precision measurement and interference of matter waves. This scheme, in addition, can be further miniaturized to construct one-dimensional, two-dimensional, and three-dimensional spatial electrostatic lattices.

The physics of W transport illuminated by recent progress in W density diagnostics at ASDEX Upgrade

NASA Astrophysics Data System (ADS)

Odstrcil, T.; Pütterich, T.; Angioni, C.; Bilato, R.; Gude, A.; Odstrcil, M.; ASDEX Upgrade Team; the EUROfusion MST1 Team

2018-01-01

Due to the high mass and charge of the heavy ions, centrifugal and electrostatic forces cause a significant variation in their poloidal density. The impact of these forces on the poloidal density profile of tungsten was investigated utilizing the detailed two-dimensional SXR emissivity profiles from the ASDEX Upgrade tokamak. The perturbation in the electrostatic potential generated by magnetic trapping of the non-thermal ions from neutral beam injection was found to be responsible for significant changes in the poloidal distribution of tungsten ions. An excellent match with the results from fast particle modeling was obtained, validating the model for the poloidal fast particle distribution. Additionally, an enhancement of the neoclassical transport due to an outboard side impurity localization was measured in the experiment when analyzing the tungsten flux between sawtooth crashes. A qualitative match with neoclassical modeling was found, demonstrating the possibility of minimizing neoclassical transport by an optimization of the poloidal asymmetry profile of the impurity.

Acceleration of ions and neutrals by a traveling electrostatic wave

NASA Astrophysics Data System (ADS)

Lee, K. H.; Lee, L. C.; Wong, A. Y.

2018-02-01

We propose a new scheme for accelerating a weakly ionized gas by externally imposing a sinusoidal electrostatic (ES) potential in a tubular system. The weakly ionized gas consists of three fluid components: neutral hydrogen fluid ( H ), positively charged fluid ( H + ), and negatively charged fluids ( H - and/or e - ), as an example. The sinusoidal ES potential is imposed on a series of conductive meshes in the tubular system, and its phase varies with time and space to mimic a traveling ES wave. The charged fluids are trapped and accelerated by the sinusoidal ES potential, while the neutral fluid is accelerated through neutral-ion collisions. The neutral fluid can be accelerated to the wave phase velocity in a few neutral-ion collision times. The whole device remains charge-neutral, and there is no build-up of space charge. The acceleration scheme can be applied to, for example, the propulsion of glider in the air, partially ionized plasma in a chamber, spacecraft, and wind tunnel.

Ion source based on the cathodic arc

DOEpatents

Sanders, David M.; Falabella, Steven

1994-01-01

A cylindrically symmetric arc source to produce a ring of ions which leave the surface of the arc target radially and are reflected by electrostatic fields present in the source to a point of use, such as a part to be coated. An array of electrically isolated rings positioned in the source serves the dual purpose of minimizing bouncing of macroparticles and providing electrical insulation to maximize the electric field gradients within the source. The source also includes a series of baffles which function as a filtering or trapping mechanism for any macroparticles.

Review of microscopic plasma processes of occurring during refilling of the plasmasphere

NASA Technical Reports Server (NTRS)

Singh, N.; Torr, D. G.

1988-01-01

Refilling of the plasmashere after geomagnetic storms involves both macroscopic and microscopic plasma processes. The latter types of processes facilitate the refilling by trapping the plasma in the flux tube and by thermalizing the interhemispheric flow. A review of studies on microscopic processes is presented. The primary focus in this review is on the processes when the density is low and the plasma is collisionless. The discussion includes electrostatic shock formation, pitch angle scatterring extended ion heating and localized ion heating in the equatorial region.

Ground-Based High-Power Microwave Decoy Discrimination System.

DTIC Science & Technology

1987-12-23

understanding of plasma instabilities, self-induced magnetic effects , space - charge considerations, production of ion currents, etc. 3.3.4 Cross-Field...breakdown, due to small potential differences. Interaction volumes can therefore be large, avoiding breakdown and space - charge effects (at the price...the interference of the incident and reflected wave, and by the electrostatic forces of the surface (positive) and space charge (negative) trapped in

A model for chorus associated electrostatic bursts

NASA Technical Reports Server (NTRS)

Grabbe, C. L.

1984-01-01

The linear theory of the generation of electrostatic bursts of noise by electrons trapped in chorus wave packets is developed for a finite temperature electron beam and a Maxwellian elecron and ion background. The growth rates determined qualitatively in good agreement with those obtained by previous authors from a more idealized model. Two connected instability mechanisms seem to be occurring: a beam plasma (electron-ion two-stream) instability commonly associated with intensification of the chorus power levels, and a transitional or borderline resistive medium instability commonly associated with chorus hooks. The physical reasons for the two mechanisms is discussed. In the second case electron beams are difficult to identify in the particle data. An expression is obtained for the maximum growth rate in terms of the ratios of the beam and electron thermal velocities to the beam velocity, and of the beam density to plasma density. It is anticipated that this may allow the observed peak in the electrostatic noise spectrum to be used as a diagnostic for the beam characteristics. Previously announced in STAR as N84-12832

Anomalous pinch of turbulent plasmas driven by the magnetic-drift-induced Lorentz force through the Stokes-Einstein relation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Shaojie, E-mail: wangsj@ustc.edu.cn

It is found that the Lorentz force generated by the magnetic drift drives a generic plasma pinch flux of particle, energy and momentum through the Stokes-Einstein relation. The proposed theoretical model applies for both electrons and ions, trapped particles, and passing particles. An anomalous parallel current pinch due to the electrostatic turbulence with long parallel wave-length is predicted.

Trapping of muscle relaxant methocarbamol degradation product by complexation with copper(II) ion: Spectroscopic and quantum chemical studies

NASA Astrophysics Data System (ADS)

Mansour, Ahmed M.; Shehab, Ola R.

2014-07-01

Structural properties of methocarbamol (Mcm) were extensively studied both experimentally and theoretically using FT IR, 1H NMR, UV-Vis., geometry optimization, Mulliken charge, and molecular electrostatic potential. Stability arises from hyper-conjugative interactions, charge delocalization and H-bonding was analyzed using natural bond orbital (NBO) analysis. Mcm was decomposed in ethanol/water mixture at 80 °C to guaifenesin [(RS)-3-(2-methoxyphenoxy)propane-1,2-diol] and carbamate ion [NH2COO-], where the degradation mechanism was explained by trapping the carbamate ion via the complexation with copper(II) ion. The structure of the isolated complex ([Cu(NH2COO)2(H2O)]ṡ4H2O) was elucidated by spectral, thermal, and magnetic tools. Electronic spectra were discussed by TD-DFT and the descriptions of frontier molecular orbitals and the relocations of the electron density were determined. Calculated g-tensor values showed best agreement with experimental values from EPR when carried out using both the B3LYP and B3PW91 functional.

Ion source based on the cathodic arc

DOEpatents

Sanders, D.M.; Falabella, S.

1994-02-01

A cylindrically symmetric arc source to produce a ring of ions which leave the surface of the arc target radially and are reflected by electrostatic fields present in the source to a point of use, such as a part to be coated, is described. An array of electrically isolated rings positioned in the source serves the dual purpose of minimizing bouncing of macroparticles and providing electrical insulation to maximize the electric field gradients within the source. The source also includes a series of baffles which function as a filtering or trapping mechanism for any macroparticles. 3 figures.

Studies on Equatorial Shock Formation During Plasmaspheric Refilling

NASA Technical Reports Server (NTRS)

Singh, Nagendra

1995-01-01

During the grant period from August 1, 1994 to October 31, 1995 we have continued to investigate the effects of plasma wave instabilities on the early stage plasmaspheric refilling. Since ion beams are the primary feature of the interhemispheric plasma flows during the early stage refilling, ion-beam driven instabilities and associated waves are of primary interest. The major findings of this research are briefly summarized here. After a systematic examination of the relevant plasma instabilities, we realized that when the interhemispheric plasma flows begin to interpenetrate at the equator, the most relevant plasma instability is the electrostatic ion cyclotron wave instability. Only at later stages the ion-acoustic instability may be affecting the plasma flow. An interesting property of the electrostatic ion cyclotron wave is that it heats ions perpendicular to the magnetic field. When the ions in the field-aligned flows are transversely heated, they are trapped in the magnetic flux tube, thus affecting the refilling process. The eic wave instability is a microprocess with scale length of the order of ion Larmor radius and the corresponding time scale is the ion cyclotron period. We have attempted to tackle the problem for the plasmaspheric refilling by incorporating the effects of eic wave instability on the mesoscale plasma flow when the properties of the latter exceeds the critical conditions for the former. We have compared the results on refilling from the model with and without the eic instability effects.

Studies on equatorial shock formation during plasmaspheric refilling

NASA Technical Reports Server (NTRS)

Singh, N.

1994-01-01

Investigations based on small-scale simulations of microprocesses occurring when a magnetic flux tube refills with a cold plasma are summarized. Results of these investigations are reported in the following attached papers: (1) 'Numerical Simulation of Filling a Magnetic Flux Tube with a Cold Plasma: The Role of Ion Beam-Driven Instabilities'; and (2) 'Numerical Simulation of Filling a Magnetic Flux Tube with a Cold Plasma: Effects of Magnetically Trapped Hot Plasma'. Other papers included are: 'Interaction of Field-Aligned Cold Plasma Flows with an Equatorially-Trapped Hot Plasma: Electrostatic Shock Formation'; and 'Comparison of Hydrodynamic and Semikinetic Treatments for a Plasma Flow along Closed Field Lines'. A proposal for further research is included.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kleinert, J.; Haimberger, C.; Zabawa, P. J.

We present a detailed description on how to build a thin wire electrostatic trap (TWIST) for ultracold polar molecules. It is the first design of an electrostatic trap that can be superimposed directly onto a magneto-optical trap (MOT). We can thus continuously produce ultracold polar molecules via photoassociation from a two species MOT and instantaneously trap them in the TWIST without the need for complex transfer schemes. Despite the spatial overlap of the TWIST and the MOT, the two traps can be operated and optimized completely independently due to the complementary nature of the utilized trapping mechanisms.

Trapping of ultracold polar molecules with a thin-wire electrostatic trap.

PubMed

Kleinert, J; Haimberger, C; Zabawa, P J; Bigelow, N P

2007-10-05

We describe the realization of a dc electric-field trap for ultracold polar molecules, the thin-wire electrostatic trap (TWIST). The thin wires that form the electrodes of the TWIST allow us to superimpose the trap onto a magneto-optical trap (MOT). In our experiment, ultracold polar NaCs molecules in their electronic ground state are created in the MOT via photoassociation, achieving a continuous accumulation in the TWIST of molecules in low-field seeking states. Initial measurements show that the TWIST trap lifetime is limited only by the background pressure in the chamber.

Electrostatic odd symmetric eigenmode in inhomogeneous Bernstein-Greene-Kruskal equilibrium

NASA Astrophysics Data System (ADS)

Woo, M.-H.; Dokgo, K.; Yoon, Peter H.; Lee, D.-Y.; Choi, Cheong R.

2018-04-01

A self-consistent electrostatic odd-symmetric eigenmode (OEM) is analytically found in a solitary type Bernstein-Greene-Kruskal (BGK) equilibrium. The frequency of the OEM is order of the electron bounce frequency and it is spatially odd-symmetric with the scale comparable to that of the solitary BGK equilibrium structure. Such an OEM is consistent with the recent observation from particle-in-cell simulation of the solitary wave [Dokgo et al., Phys. Plasmas 23, 092107 (2016)]. The mode can be driven unstable by trapped electrons within the hole structure of the solitary wave. Such a low frequency, pure electron mode, which may possibly interact resonantly with the ion acoustic mode, provides a possible damping mechanism of the BGK equilibrium.

Obliquely propagating ion acoustic solitary structures in the presence of quantized magnetic field

NASA Astrophysics Data System (ADS)

Iqbal Shaukat, Muzzamal

2017-10-01

The effect of linear and nonlinear propagation of electrostatic waves have been studied in degenerate magnetoplasma taking into account the effect of electron trapping and finite temperature with quantizing magnetic field. The formation of solitary structures has been investigated by employing the small amplitude approximation both for fully and partially degenerate quantum plasma. It is observed that the inclusion of quantizing magnetic field significantly affects the propagation characteristics of the solitary wave. Importantly, the Zakharov-Kuznetsov equation under consideration has been found to allow the formation of compressive solitary structures only. The present investigation may be beneficial to understand the propagation of nonlinear electrostatic structures in dense astrophysical environments such as those found in white dwarfs.

The MR-TOF-MS isobar separator for the TITAN facility at TRIUMF

NASA Astrophysics Data System (ADS)

Jesch, Christian; Dickel, Timo; Plaß, Wolfgang R.; Short, Devin; Ayet San Andres, Samuel; Dilling, Jens; Geissel, Hans; Greiner, Florian; Lang, Johannes; Leach, Kyle G.; Lippert, Wayne; Scheidenberger, Christoph; Yavor, Mikhail I.

2015-11-01

At TRIUMF's Ion Trap for Atomic and Nuclear Science (TITAN) a multiple-reflection time-of-flight mass spectrometer (MR-TOF-MS) will extend TITAN's capabilities and facilitate mass measurements and in-trap decay spectroscopy of exotic nuclei that so far have not been possible due to strong isobaric contamination. This MR-TOF-MS will also enable mass measurements of very short-lived nuclides (half-life > 1 ms) that are produced in very low quantities (a few detected ions overall). In order to allow the installation of an MR-TOF-MS in the restricted space on the platform, on which the TITAN facility is located, novel mass spectrometric methods have been developed. Transport, cooling and distribution of the ions inside the device is done using a buffer gas-filled RFQ-based ion beam switchyard. Mass selection is achieved using a dynamic retrapping technique after time-of-flight analysis in an electrostatic isochronous reflector system. Only due to the combination of these novel methods the realization of an MR-TOF-MS based isobar separator at TITAN has become possible. The device has been built, commissioned off-line and is currently under installation at TITAN.

Resilience of quasi-isodynamic stellarators against trapped-particle instabilities.

PubMed

Proll, J H E; Helander, P; Connor, J W; Plunk, G G

2012-06-15

It is shown that in perfectly quasi-isodynamic stellarators, trapped particles with a bounce frequency much higher than the frequency of the instability are stabilizing in the electrostatic and collisionless limit. The collisionless trapped-particle instability is therefore stable as well as the ordinary electron-density-gradient-driven trapped-electron mode. This result follows from the energy balance of electrostatic instabilities and is thus independent of all other details of the magnetic geometry.

Nonlinear dynamics of resonant electrons interacting with coherent Langmuir waves

NASA Astrophysics Data System (ADS)

Tobita, Miwa; Omura, Yoshiharu

2018-03-01

We study the nonlinear dynamics of resonant particles interacting with coherent waves in space plasmas. Magnetospheric plasma waves such as whistler-mode chorus, electromagnetic ion cyclotron waves, and hiss emissions contain coherent wave structures with various discrete frequencies. Although these waves are electromagnetic, their interaction with resonant particles can be approximated by equations of motion for a charged particle in a one-dimensional electrostatic wave. The equations are expressed in the form of nonlinear pendulum equations. We perform test particle simulations of electrons in an electrostatic model with Langmuir waves and a non-oscillatory electric field. We solve equations of motion and study the dynamics of particles with different values of inhomogeneity factor S defined as a ratio of the non-oscillatory electric field intensity to the wave amplitude. The simulation results demonstrate deceleration/acceleration, thermalization, and trapping of particles through resonance with a single wave, two waves, and multiple waves. For two-wave and multiple-wave cases, we describe the wave-particle interaction as either coherent or incoherent based on the probability of nonlinear trapping.

TITAN's multiple-reflection time-of-flight isobar separator

NASA Astrophysics Data System (ADS)

Reiter, Moritz Pascal; Titan Collaboration

2016-09-01

At the ISAC facility located at TRIUMF exotic nuclei are produced by the ISOL method. Exotic nuclei are separated by a magnetic separator and transported to TRIUMF's Ion Trap for Atomic and Nuclear science (TITAN). TITAN is a system of multiple ion traps for high precision mass measurements and in-trap decay spectroscopy. Although ISAC can deliver some of the highest yields for even many of the most exotic species many measurements suffer from a strong isobaric background. This background often prevents the high precision measurement of the species of interest. To overcome this limitation an additional isobar separator based on the Multiple-Reflection Time-Of-Flight Mass Spectrometry (MR-TOF-MS) technique has been developed for TITAN. Mass selection is achieved using dynamic re-trapping of the species of interest after a time-of-flight analysis in an electrostatic isochronous reflector system. Additionally the MR-TOF-MS will, on its own, enable mass measurements of very short-lived nuclides that are weakly produced. Being able to measure all isobars of a given mass number at the same time the MR-TOF-MS can be used for beam diagnostics or determination of beam compositions. Results from the offline commissioning showing mass resolving power and separation power will be presented.

Electrostatic Charging and Particle Interactions in Microscopic Insulating Grains

NASA Astrophysics Data System (ADS)

Lee, Victor

In this thesis, we experimentally investigate the electrostatic charging as well as the particle interactions in microscopic insulating grains. First, by tracking individual grains accelerated in an electric field, we quantitatively demonstrate that tribocharging of same-material grains depends on particle size. Large grains tend to charge positively, and small ones tend to charge negatively. Theories based on the transfer of trapped electrons can explain this tendency but have not been validated. Here we show that the number of trapped electrons, measured independently by a thermoluminescence technique, is orders of magnitude too small to be responsible for the amount of charge transferred. This result reveals that trapped electrons are not responsible for same-material tribocharging of dielectric particles. Second, same-material tribocharging in grains can result in important long-range electrostatic interactions. However, how these electrostatic interactions contribute to particle clustering remains elusive, primarily due to the lack of direct, detailed observations. Using a high-speed camera that falls with a stream charged grains, we observe for the first time how charged grains can undergo attractive as well as repulsive Kepler-like orbits. Charged particles can be captured in their mutual electrostatic potential and form clusters via multiple bounces. Dielectric polarization effects are directly observed, which lead to additional attractive forces and stabilize "molecule-like" arrangements of charged particles. Third, we have developed a new method to study the charge transfer of microscopic particles based on acoustic levitation techniques. This method allows us to narrow the complex problem of many-particle charging down to precise charge measurements of a single sub-millimeter particle colliding with a target plate. By simply attaching nonpolar groups onto glass surfaces, we show that the contact charging of a particle is highly dependent on hydrophobicity. Charging between a hydrophilic and a hydrophobic surface is enhanced in a basic atmosphere and suppressed in an acidic one. Moreover, hydrophobicity is also found to play a key role in particle charging driven by an external electric field. These results strongly support the idea that aqueous-ion transfer is responsible for the particle contact charging phenomenon.

Resonant ion acceleration by plasma jets: Effects of jet breaking and the magnetic-field curvature.

PubMed

Artemyev, A V; Vasiliev, A A

2015-05-01

In this paper we consider resonant ion acceleration by a plasma jet originating from the magnetic reconnection region. Such jets propagate in the background magnetic field with significantly curved magnetic-field lines. Decoupling of ion and electron motions at the leading edge of the jet results in generation of strong electrostatic fields. Ions can be trapped by this field and get accelerated along the jet front. This mechanism of resonant acceleration resembles surfing acceleration of charged particles at a shock wave. To describe resonant acceleration of ions, we use adiabatic theory of resonant phenomena. We show that particle motion along the curved field lines significantly influences the acceleration rate. The maximum gain of energy is determined by the particle's escape from the system due to this motion. Applications of the proposed mechanism to charged-particle acceleration in the planetary magnetospheres and the solar corona are discussed.

Ion related problems for the XLS ring

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bozoki, E.; Halama, H.

1989-07-11

The electron beam in the XLS will collide with the residual gas in the vacuum chamber. The positive ions will be trapped in the potential well of the electron beam. They will perform stable or unstable oscillations around the beam under the repetitive Coulomb force of the bunches. If not cleared, the captured ions will lead to partial or total neutralization of the beam, causing both, a decrease of life-time and a change in the vertical tunes as well as an increase in the tune-spread. They can also cause coherent transverse instabilities. The degree of neutralization {theta} that one canmore » tolerate, is primarily determined by the allowable tune shift, which of the XLS is between 1 and 5 10{sup {minus}3}. Electrostatic clearing electrodes will be used to keep the neutralization below the desired limit. In order to determine their location and the necessary clearing-rate and voltage, we examine the ion production rate, longitudinal velocity of ions in field-free regions and in the dipoles to see what distance the ions can travel without clearing before the neutralization of the beam reaches the prescribed limit, beam potential to see the locations of the potential wells, voltage requirements for ion clearing, critical mass for ion capture in the bunched beam, tune shift caused by neutralization of the beam, pressure rise due to the trapped ions and power dissipation due to beam image current. 13 refs., 3 figs., 4 tabs.« less

Overview of the High Performance Antiproton (HiPAT) Experiment

NASA Technical Reports Server (NTRS)

Martin, James J.; Sims, William H.; Chakrabarti, Suman; Pearson, Boise; Fant, Wallace E.; Lewis, Raymond A.; Rodgers, Stephen (Technical Monitor)

2002-01-01

The annihilation of matter with antimatter represents the highest energy density of any known reaction, producing 10(exp 8) MJ/g, approximately 10 orders of magnitude more energy per unit mass than chemical based combustion. To take the first step towards using this energy for propulsion applications the NASA MSFC Propulsion Research Center (PRC) has initiated a research activity examining the storage of low energy antiprotons. Storage was identified as a key enabling technology since it builds the experience base necessary to understand the handling of antiprotons for virtually all utilization and high-density storage concepts. To address this need, a device referred to as the High Performance Antiproton Trap (HiPAT) is under development at the NASA MSFC PRC. The HiPAT is an electromagnetic system (Penning-Malmberg design) consisting of a 4 Tesla superconductor, a high voltage confinement electrode system (operation up to 20 KV), and an ultra high vacuum test section (operating in the 10(exp -12) torr range). The system was designed to be portable with an ultimate goal of maintaining 10(exp 12) charged particles with a half-life of 18 days. Currently, this system is being experimentally evaluated using normal matter ions which are cheap to produce and relatively easy to handle. These normal ions provide a good indication of overall trap behavior, with the exception of assessing annihilation losses. The ions are produced external to HiPAT using two hydrogen ion sources, with adjustable beam energy and current. Ion are transported in a beam line and controlled through the use of electrostatic optics. These optics serve to both focus and gate the incoming ions, providing microsecond-timed pulses that are dynamically captured by cycling the HiPAT electric containment field like a 'trap door'. The layout of this system more closely simulates the operations expected at an actual antiproton production facility where 'packets' of antiprotons with pulse widths measured in 100's of nanoseconds could be provided. Initial dynamic capture experiments have been performed with both trap and ton source system functioning at approximately 10% of maximum levels, minimizing the potential for extraneous effects. Dynamic trapping techniques demonstrated the successful capture of millions of hydrogen ions with good agreement with the predicted loading based on the timing sequence, trap electric field, and ion beam current. These techniques will be expanded to examine multiple shot capture or 'stacking' to increase the total number of ions stored within HiPAT.

Plasmas in compact traps: From ion sources to multidisciplinary research

NASA Astrophysics Data System (ADS)

Mascali, D.; Musumarra, A.; Leone, F.; Galatà, A.; Romano, F. P.; Gammino, S.

2017-09-01

In linear (minimum-B) magneto-static traps dense and hot plasmas are heated by electromagnetic radiation in the GHz domain via the Electron Cyclotron Resonance (ECR). The values of plasma density, temperature and confinement times ( n_eτ_i>10^{13} cm ^{-3} s; T_e>10 keV) are similar to the ones of thermonuclear plasmas. The research in this field -devoted to heating and confinement optimization- has been supported by numerical modeling and advanced diagnostics, for probing the plasma especially in a non-invasive way. ECR-based systems are nowadays able to produce extremely intense (tens or hundreds of mA) beams of light ions (p, d, He), and relevant currents of heavier elements (C, O, N) up to heavy ions like Xe, Pb, U. Such beams can be extracted from the trap by a proper electrostatic system. The above-mentioned properties make these plasmas very attractive for interdisciplinary researches also, such as i) nuclear decays rates measurements in stellar-like conditions, ii) energy conversion studies, being exceptional sources of short-wavelength electromagnetic radiation (EUV, X-rays, hard X-rays and gammas, useful in material science and archaeometry), iii) environments allowing precise spectroscopical measurements as benchmarks for magnetized astrophysical plasmas. The talk will give an overview about the state-of-the-art in the field of intense ion sources, and some new perspectives for interdisciplinary research, with a special attention to the developments based at INFN-LNS.

Ion acceleration by laser hole-boring into plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pogorelsky, I. V.; Dover, N. P.; Babzien, M.

By experiment and simulations, we study the interaction of an intense CO{sub 2} laser pulse with slightly overcritical plasmas of fully ionized helium gas. Transverse optical probing is used to show a recession of the front plasma surface with an initial velocity >10{sup 6} m/s driven by hole-boring by the laser pulse and the resulting radiation pressure driven electrostatic shocks. The collisionless shock propagates through the plasma, dissipates into an ion-acoustic solitary wave, and eventually becomes collisional as it slows further. These observations are supported by PIC simulations which prove the conclusion that monoenergetic protons observed in our earlier reportedmore » experiment with a hydrogen jet result from ion trapping and reflection from a shock wave driven through the plasma.« less

Auroral-particle precipitation and trapping caused by electrostatic double layers in the ionosphere.

PubMed

Albert, R D; Lindstrom, P J

1970-12-25

Interpretation of high-resolution angular distribution measurements of the primary auroral electron flux detected by a rocket probe launched into a visible aurora from Fort Churchill in the fall of 1966 leads to the following conclusions. The auroral electron flux is nearly monoenergetic and has a quasi-trapped as well as a precipitating component. The quasi-trapped flux appears to be limited to a region defined by magnetic-mirror points and multiple electrostatic double layers in the ionosphere. The electrostatic field of the double-layer distribution enhances the aurora by lowering the magnetic-mirror points and supplying energy to the primary auroral electrons.

Piezoelectrically-induced trap-depth reduction model of elastico-mechanoluminescent materials

NASA Astrophysics Data System (ADS)

Chandra, B. P.; Chandra, V. K.; Jha, Piyush

2015-03-01

Considering the detrapping of charge carriers due to reduction in trap-depth caused by piezoelectric field produced by applied pressure, an expression is derived for the detrapping rate of electrons. Then, an expression is obtained for the rate of generation of excited ions produced during capture of detrapped electrons by Eu3+ ions in persistent luminescent materials or by the energy released during electron-hole recombination in ZnS:Mn crystals. Finally, an expression is explored for the elastico-mechanoluminescence (EML) intensity, which is able to explain satisfactorily the characteristics of EML for the application of static pressure as well as for impact pressure. The total number of detrapped electrons and the total EML intensity are found to increase linearly with the electrostatic energy of the crystals in piezoelectric field. It is shown that the EML intensity should increase with the EML efficiency, number of crystallites (volume of sample), concentration of local piezoelectric regions in crystallites, piezoelectric constant of local piezoelectric regions, average length of the local piezoelectric regions, total number of electron traps, pressing rate, and applied pressure, and it should be higher for the materials having low value of threshold pressure and low value of trap-depth in unstressed condition. On the basis of the piezoelectrically-induced trap-depth reduction model of EML reported in the present investigation novel intense elastico mechanoluminescent materials having repetitive EML with undiminished intensity for successive loadings can be tailored which may find applications in sensing, imaging, lighting, colored displays, and other mechano-optical devices.

Development and Use of Fluorescent Antibody and qPCR Protocols for the Electrostatic Spore Trap

USDA-ARS?s Scientific Manuscript database

Fluorescent antibody (FA) and qPCR protocols were evaluated for the newly developed aerobiological sampler (Ionic Spore Trap), which depends upon electrostatic deposition of particulates onto a 25 mm aluminum disk (stub). This device was originally designed for assessment of captured particulates by...

Verification of nonlinear particle simulation of radio frequency waves in fusion plasmas

NASA Astrophysics Data System (ADS)

Kuley, Animesh; Bao, Jian; Lin, Zhihong

2015-11-01

Nonlinear global particle simulation model has been developed in GTC to study the nonlinear interactions of radio frequency (RF) waves with plasmas in tokamak. In this model, ions are considered as fully kinetic particles using the Vlasov equation and electrons are treated as guiding centers using the drift kinetic. Boris push scheme for the ion motion has been implemented in the toroidal geometry using magnetic coordinates and successfully verified for the ion cyclotron, ion Bernstein and lower hybrid waves. The nonlinear GTC simulation of the lower hybrid wave shows that the amplitude of the electrostatic potential is oscillatory due to the trapping of resonant electrons by the electric field of the lower hybrid wave. The nonresonant parametric decay is observed an IBW sideband and an ion cyclotron quasimode (ICQM). The ICQM induces an ion perpendicular heating with a heating rate proportional to the pump wave intensity. This work is supported by PPPL subcontract number S013849-F and US Department of Energy (DOE) SciDAC GSEP Program.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ali, S.; Bukhari, S.; Department of Physics, The University of Azad Jammu and Kashmir, Muzaffarabad 13100, Azad Kashmir

Keeping in view the kinetic treatment for plasma particles, the electrostatic twisted dust-acoustic (DA) and dust-ion-acoustic (DIA) waves are investigated in a collisionless unmagnetized multi-component dusty plasma, whose constituents are the electrons, singly ionized positive ions, and negatively charged massive dust particulates. With this background, the Vlasov–Poisson equations are coupled together to derive a generalized dielectric constant by utilizing the Laguerre-Gaussian perturbed distribution function and electrostatic potential in the paraxial limit. The dispersion and damping rates of twisted DA and DIA waves are analyzed with finite orbital angular momentum states in a multi-component dusty plasma. Significant modifications concerning the realmore » wave frequencies and damping rates appeared with varying twisted dimensionless parameter and dust concentration. In particular, it is shown that dust concentration enhances the phase speed of the DIA waves in contrary to DA waves, whereas the impact of twisted parameter reduces the frequencies of both DA and DIA waves. The results should be useful for the understanding of particle transport and trapping phenomena caused by wave excitation in laboratory dusty plasmas.« less

Preparation of translationally cold neutral molecules.

PubMed

Di Domenicantonio, Giulia; Bertsche, Benjamin; Osterwalder, Andreas

2011-01-01

Efforts at EPFL to obtain translationally cold neutral molecules are described. Active deceleration of polar molecules is performed by confining the molecules in moving three-dimensional electrostatic traps, and by appropriately choosing the velocity of those traps. Alternatively, cold molecules can be obtained by velocity filtering. Here, the velocity of the molecules is not changed, but instead the cold molecules are extracted from a thermal sample by using the competition between the electrostatic force and the centrifugal force inside a bent electrostatic guide for polar molecules.

Jupiter plasma wave observations: an initial voyager 1 overview.

PubMed

Scarf, F L; Gurnett, D A; Kurth, W S

1979-06-01

The Voyager I plasma wave instrument detected low-frequency radio emissions, ion acoustic waves, and electron plasma oscillations for a period of months before encountering Jupiter's bow shock. In the outer magnetosphere, measurements of trapped radio waves were used to derive an electron density profile. Near and within the Io plasma torus the instrument detected high-frequency electrostatic waves, strong whistler mode turbulence, and discrete whistlers, apparently associated with lightning. Some strong emissions in the tail region and some impulsive signals have not yet been positively identified.

Effects of non-Gaussian Brownian motion on direct force optical tweezers measurements of the electrostatic forces between pairs of colloidal particles.

PubMed

Raudsepp, Allan; A K Williams, Martin; B Hall, Simon

2016-07-01

Measurements of the electrostatic force with separation between a fixed and an optically trapped colloidal particle are examined with experiment, simulation and analytical calculation. Non-Gaussian Brownian motion is observed in the position of the optically trapped particle when particles are close and traps weak. As a consequence of this motion, a simple least squares parameterization of direct force measurements, in which force is inferred from the displacement of an optically trapped particle as separation is gradually decreased, contains forces generated by the rectification of thermal fluctuations in addition to those originating directly from the electrostatic interaction between the particles. Thus, when particles are close and traps weak, simply fitting the measured direct force measurement to DLVO theory extracts parameters with modified meanings when compared to the original formulation. In such cases, however, physically meaningful DLVO parameters can be recovered by comparing the measured non-Gaussian statistics to those predicted by solutions to Smoluchowski's equation for diffusion in a potential.

Electrostatic-spray ionization mass spectrometry sniffing for perfume fingerprinting.

PubMed

Tobolkina, Elena; Qiao, Liang; Xu, Guobin; Girault, Hubert H

2013-11-15

The perfume market is growing significantly, and it is easy to find imitative fragrances of probably all types of perfume. Such imitative fragrances are usually of lower quality than the authentic ones, creating a possible threat for perfume companies. Therefore, it is important to develop efficient chemical analysis techniques to screen rapidly perfume samples. Electrostatic-spray ionization (ESTASI) was used to analyze directly samples sprayed or deposited on different types of paper. A linear ion trap mass spectrometer was used to detect the ions produced by ESTASI with a modified extended transfer capillary for 'sniffing' ions from the paper. Several commercial perfumes and a model perfume were analyzed by ESTASI-sniffing. The results obtained by paper ESTASI-MS of commercial fragrances were compared with those obtained from ESI-MS. In addition, a commercial fragrance was first nebulized on the hand and then soaked up by blotting paper, which was afterwards placed on an insulating plate for ESTASI-MS analysis. Analysis of peptides and proteins was also performed to show that the paper ESTASI-MS could be used for samples with very different molecular masses. Paper ESTASI-MS yields a rapid fingerprinting characterization of perfume fragrances, avoiding time-consuming sample-preparation steps, and thereby performing a rapid screening in a few seconds. Copyright © 2013 John Wiley & Sons, Ltd.

On the correct implementation of Fermi-Dirac statistics and electron trapping in nonlinear electrostatic plane wave propagation in collisionless plasmas

NASA Astrophysics Data System (ADS)

Schamel, Hans; Eliasson, Bengt

2016-05-01

Quantum statistics and electron trapping have a decisive influence on the propagation characteristics of coherent stationary electrostatic waves. The description of these strictly nonlinear structures, which are of electron hole type and violate linear Vlasov theory due to the particle trapping at any excitation amplitude, is obtained by a correct reduction of the three-dimensional Fermi-Dirac distribution function to one dimension and by a proper incorporation of trapping. For small but finite amplitudes, the holes become of cnoidal wave type and the electron density is shown to be described by a ϕ ( x ) 1 / 2 rather than a ϕ ( x ) expansion, where ϕ ( x ) is the electrostatic potential. The general coefficients are presented for a degenerate plasma as well as the quantum statistical analogue to these steady state coherent structures, including the shape of ϕ ( x ) and the nonlinear dispersion relation, which describes their phase velocity.

Low-Frequency Microinstabilities in Rotating Tokamak Plasmas.

NASA Astrophysics Data System (ADS)

Artun, Mehmet

1994-01-01

Low-frequency drift-type microinstabilities have often been suggested as the leading candidates to account for the anomalously large transport; observed in tokamak plasmas. The effects of sheared equilibrium flows on this important class of instabilities is systematically investigated in the present thesis. In particular, the analysis is carried out in two parts. In order to gain some insight into the key elements of this problem, the first part deals with the stability properties of the kinetic ion temperature gradient mode under the influence of parallel and perpendicular shear flows in a simplified sheared magnetic slab geometry. The eigenmode analysis is performed using a shooting code for long-wavelength modes (k_|rho _{i} << 1), and an integral eigenmode code for short-wavelength modes (k_ |rho_{i} ~ 1). Numerical results are cross-checked with analytical estimates in the fluid regime. While the differential analysis is mostly limited to ground state modes of the system--due to the requirement that the average perpendicular wavenumber be small--the integral eigenmode code has been used to calculate higher radial eigenmodes with confidence. New features observed through the introduction of shear flows are discussed. In the second part we present the shear flow generalization of the nonlinear electromagnetic gyrokinetic equation for realistic toroidal geometry. In accordance with the most natural choice for such studies, the coordinate frame is chosen to be shifted in velocity space and unchanged in configuration space. The natural equilibrium constraints of the toroidal problem limits the choice of the flow profile to that in which the angular velocity is a function of the flux surface. The general form of the gyrokinetic equation obtained is then used to derive the two-dimensional linear electrostatic eigenmode equation in circular toroidal geometry including trapped particle effects. In addition to magnetic trapping, electrostatic and centrifugal trapping are also found to play an important role here. A modified version of a finite element code is utilized to analyze shear flow effects on the trapped ion mode (TIM) in the long wavelength limit. Numerical results for fully coupled as well as single poloidal harmonic cases are presented. Implications of the results obtained in the present investigation are discussed and suggestions are given for future studies.

Atomic ion clock with two ion traps, and method to transfer ions

NASA Technical Reports Server (NTRS)

Prestage, John D. (Inventor); Chung, Sang K. (Inventor)

2011-01-01

An atomic ion clock with a first ion trap and a second ion trap, where the second ion trap is of higher order than the first ion trap. In one embodiment, ions may be shuttled back and forth from one ion trap to the other by application of voltage ramps to the electrodes in the ion traps, where microwave interrogation takes place when the ions are in the second ion trap, and fluorescence is induced and measured when the ions are in the first ion trap. In one embodiment, the RF voltages applied to the second ion trap to contain the ions are at a higher frequency than that applied to the first ion trap. Other embodiments are described and claimed.

Simulation of linear and nonlinear Landau damping of lower hybrid waves

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qi, Lei; Wang, X. Y.; Lin, Y.

2013-06-15

The linear physics of lower hybrid waves (LHWs) and their nonlinear interaction with particles through Landau damping are studied with the gyrokinetic electron and fully kinetic ion (GeFi) particle simulation model in the electrostatic limit. Unlike most other wave modes, the LHWs can resonantly interact with both electrons and ions, with the former being highly magnetized and latter nearly unmagnetized around the lower hybrid frequency. Direct interactions of LHWs with electrons and/or ions are investigated for cases with various k{sub ∥}/k,T{sub i}/T{sub e}, and wave amplitudes. In the linear electron Landau damping (ELD), the dispersion relation and the linear dampingmore » rate obtained from our simulation agree well with the analytical linear theory. As the wave amplitude increases, the nonlinear Landau effects are present, and a transition from strong decay at smaller amplitudes to weak decay at larger amplitudes is observed. In the nonlinear stage, the LHWs in the long time evolution finally exhibit a steady Bernstein-Greene-Kruskal mode, in which the wave amplitude is saturated above the noise level. While the resonant electrons are trapped in the wave field in the nonlinear ELD, the resonant ions are untrapped in the LHW time scales. The ion Landau damping is thus predominantly in a linear fashion, leading to a wave saturation level significantly lower than that in the ELD. On the long time scales, however, the ions are still weakly trapped. The results show a coupling between the LHW frequency and the ion cyclotron frequency during the long-time LHW evolution.« less

Fluid aspects of electron streaming instability in electron-ion plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jao, C.-S.; Hau, L.-N.; Department of Physics, National Central University, Jhongli, Taiwan

2014-02-15

Electrons streaming in a background electron and ion plasma may lead to the formation of electrostatic solitary wave (ESW) and hole structure which have been observed in various space plasma environments. Past studies on the formation of ESW are mostly based on the particle simulations due to the necessity of incorporating particle's trapping effects. In this study, the fluid aspects and thermodynamics of streaming instabilities in electron-ion plasmas including bi-streaming and bump-on-tail instabilities are addressed based on the comparison between fluid theory and the results from particle-in-cell simulations. The energy closure adopted in the fluid model is the polytropic lawmore » of d(pρ{sup −γ})/dt=0 with γ being a free parameter. Two unstable modes are identified for the bump-on-tail instability and the growth rates as well as the dispersion relation of the streaming instabilities derived from the linear theory are found to be in good agreement with the particle simulations for both bi-streaming and bump-on-tail instabilities. At the nonlinear saturation, 70% of the electrons are trapped inside the potential well for the drift velocity being 20 times of the thermal velocity and the pρ{sup −γ} value is significantly increased. Effects of ion to electron mass ratio on the linear fluid theory and nonlinear simulations are also examined.« less

[Screening and confirmation of 24 hormones in cosmetics by ultra high performance liquid chromatography-linear ion trap/orbitrap high resolution mass spectrometry].

PubMed

Li, Zhaoyong; Wang, Fengmei; Niu, Zengyuan; Luo, Xin; Zhang, Gang; Chen, Junhui

2014-05-01

A method of ultra high performance liquid chromatography-linear ion trap/orbitrap high resolution mass spectrometry (UPLC-LTQ/Orbitrap MS) was established to screen and confirm 24 hormones in cosmetics. Various cosmetic samples were extracted with methanol. The extract was loaded onto a Waters ACQUITY UPLC BEH C18 column (50 mm x 2.1 mm, 1.7 microm) using a gradient elution of acetonitrile/water containing 0.1% (v/v) formic acid for the separation. The accurate mass of quasi-molecular ion was acquired by full scanning of electrostatic field orbitrap. The rapid screening was carried out by the accurate mass of quasi-molecular ion. The confirmation analysis for targeted compounds was performed with the retention time and qualitative fragments obtained by data dependent scan mode. Under the optimal conditions, the 24 hormones were routinely detected with mass accuracy error below 3 x 10(-6) (3 ppm), and good linearities were obtained in their respective linear ranges with correlation coefficients higher than 0.99. The LODs (S/N = 3) of the 24 compounds were < or = 10 microg/kg, which can meet the requirements for the actual screening of cosmetic samples. The developed method was applied to screen the hormones in 50 cosmetic samples. The results demonstrate that the method is a useful tool for the rapid screening and identification of the hormones in cosmetics.

Ferroelectric nanotraps for polar molecules

NASA Astrophysics Data System (ADS)

Dutta, Omjyoti; Giedke, G.

2018-02-01

We propose and analyze an electrostatic-optical nanoscale trap for cold diatomic polar molecules. The main ingredient of our proposal is a square array of ferroelectric nanorods with alternating polarization. We show that, in contrast to electrostatic traps using the linear Stark effect, a quadratic Stark potential supports long-lived trapped states. The molecules are kept at a fixed height from the nanorods by a standing-wave optical dipole trap. For the molecules and materials considered, we find nanotraps with trap frequency up to 1 MHz, ground-state width ˜20 nm with lattice periodicity of ˜200 nm . Analyzing the loss mechanisms due to nonadiabaticity, surface-induced radiative transitions, and laser-induced transitions, we show the existence of trapped states with lifetime ˜1 s , competitive with current traps created via optical mechanisms. As an application we extend our discussion to a one-dimensional (1D) array of nanotraps to simulate a long-range spin Hamiltonian in our structure.

Miniature Electrostatic Ion Thruster With Magnet

NASA Technical Reports Server (NTRS)

Hartley, Frank T.

2006-01-01

A miniature electrostatic ion thruster is proposed that, with one exception, would be based on the same principles as those of the device described in the previous article, "Miniature Bipolar Electrostatic Ion Thruster". The exceptional feature of this thruster would be that, in addition to using electric fields for linear acceleration of ions and electrons, it would use a magnetic field to rotationally accelerate slow electrons into the ion stream to neutralize the ions.

Universal collisional activation ion trap mass spectrometry

DOEpatents

McLuckey, S.A.; Goeringer, D.E.; Glish, G.L.

1993-04-27

A universal collisional activation ion trap comprises an ion trapping means containing a bath gas and having connected thereto a noise signal generator. A method of operating a universal collisional activation ion trap comprises the steps of: providing an ion trapping means; introducing into the ion trapping means a bath gas; and, generating a noise signal within the ion trapping means; introducing into the ion trapping means a substance that, when acted upon by the noise signal, undergoes collisional activation to form product ions.

Universal collisional activation ion trap mass spectrometry

DOEpatents

McLuckey, Scott A.; Goeringer, Douglas E.; Glish, Gary L.

1993-01-01

A universal collisional activation ion trap comprises an ion trapping means containing a bath gas and having connected thereto a noise signal generator. A method of operating a universal collisional activation ion trap comprises the steps of: providing an ion trapping means; introducing into the ion trapping means a bath gas; and, generating a noise signal within the ion trapping means; introducing into the ion trapping means a substance that, when acted upon by the noise signal, undergoes collisional activation to form product ions.

Non-destructive ion trap mass spectrometer and method

DOEpatents

Frankevich, Vladimir E.; Soni, Manish H.; Nappi, Mario; Santini, Robert E.; Amy, Jonathan W.; Cooks, Robert G.

1997-01-01

The invention relates to an ion trap mass spectrometer of the type having an ion trapping volume defined by spaced end caps and a ring electrode. The ion trap includes a small sensing electrode which senses characteristic motion of ions trapped in said trapping volume and provides an image current. Ions are excited into characteristic motion by application of an excitation pulse to the trapped ions. The invention also relates to a method of operating such an ion trap.

Enabling Exploration of Deep Space: High Density Storage of Antimatter

NASA Technical Reports Server (NTRS)

Smith, Gerald A.; Kramer, Kevin J.

1999-01-01

Portable electromagnetic antiproton traps are now in a state of realization. This allows facilities like NASA Marshall Space Flight Center to conduct antimatter research remote to production sites. MSFC is currently developing a trap to store 10(exp 12) antiprotons for a twenty-day half-life period to be used in future experiments including antimatter plasma guns, antimatter-initiated microfusion, and the synthesis of antihydrogen for space propulsion applications. In 1998, issues including design, safety and transportation were considered for the MSFC High Performance Antimatter Trap (HiPAT). Radial diffusion and annihilation losses of antiprotons prompted the use of a 4 Tesla superconducting magnet and a 20 KV electrostatic potential at 10(exp -12) Torr pressure. Cryogenic fluids used to maintain a trap temperature of 4K were sized accordingly to provide twenty days of stand-alone storage time (half-life). Procurement of the superconducting magnet with associated cryostat has been completed. The inner, ultra-high vacuum system with electrode structures has been fabricated, tested and delivered to MSFC along with the magnet and cryostat. Assembly of these systems is currently in progress. Testing under high vacuum conditions, using electrons and hydrogen ions will follow in the months ahead.

Angular trapping of anisometric nano-objects in a fluid.

PubMed

Celebrano, Michele; Rosman, Christina; Sönnichsen, Carsten; Krishnan, Madhavi

2012-11-14

We demonstrate the ability to trap, levitate, and orient single anisometric nanoscale objects with high angular precision in a fluid. An electrostatic fluidic trap confines a spherical object at a spatial location defined by the minimum of the electrostatic system free energy. For an anisometric object and a potential well lacking angular symmetry, the system free energy can further strongly depend on the object's orientation in the trap. Engineering the morphology of the trap thus enables precise spatial and angular confinement of a single levitating nano-object, and the process can be massively parallelized. Since the physics of the trap depends strongly on the surface charge of the object, the method is insensitive to the object's dielectric function. Furthermore, levitation of the assembled objects renders them amenable to individual manipulation using externally applied optical, electrical, or hydrodynamic fields, raising prospects for reconfigurable chip-based nano-object assemblies.

The electrostatic fluidic trap: a new approach to the spatial control and manipulation of matter at the nanometer scale (presentation video)

NASA Astrophysics Data System (ADS)

Krishnan, Madhavi

2014-09-01

I will describe a new technique to trap matter at the nanometer scale in fluids. Rather than apply external fields to the object of interest, our approach relies on spatial tailoring of the interaction between an object and its neighbouring surfaces in order to create spatial potential minima in three dimensions. We demonstrate how the strong and long-ranged electrostatic interaction can be modulated by tailoring substrate geometry to achieve stable spatial trapping of charged objects, as small as single proteins in solution.

Metal ion reactive thin films using spray electrostatic LbL assembly.

PubMed

Krogman, Kevin C; Lyon, Katharine F; Hammond, Paula T

2008-11-20

By using the spray-layer-by-layer (Spray-LbL) technique, the number of metal counterions trapped within LbL coatings is significantly increased by kinetically freezing the film short of equilibrium, potentially limiting interchain penetration and forcing chains to remain extrinsically compensated to a much greater degree than observed in the traditional dipped LbL technique. The basis for the enhanced entrapment of metal ions such as Cu2+, Fe2+, and Ag+ is addressed, including the equilibrium driving force for extrinsic compensation by soft versus hard metal ions and the impact of Spray-LbL on the kinetics of polymer-ion complexation. These polymer-bound metal-ion coatings are also demonstrated to be effective treatments for air filtration, functionalizing existing filters with the ability to strongly bind toxic industrial compounds such as ammonia or cyanide gases, as well as chemical warfare agent simulants such as chloroethyl ethyl sulfide. On the basis of results reported here, future work could extend this method to include other toxic soft-base ligands such as carbon monoxide, benzene, or organophosphate nerve agents.

Vibrational Spectroscopy of Fluoroformate, FCO2-, Trapped in Helium Nanodroplets.

PubMed

Thomas, Daniel A; Mucha, Eike; Gewinner, Sandy; Schöllkopf, Wieland; Meijer, Gerard; von Helden, Gert

2018-05-03

Fluoroformate, also known as carbonofluoridate, is an intriguing molecule readily formed by the reductive derivatization of carbon dioxide. In spite of its well-known stability, a detailed structural characterization of the isolated anion has yet to be reported. Presented in this work is the vibrational spectrum of fluoroformate obtained by infrared action spectroscopy of ions trapped in helium nanodroplets, the first application of this technique to a molecular anion. The experimental method yields narrow spectral lines, providing experimental constraints on the structure that can be accurately reproduced using high-level ab initio methods. In addition, two notable Fermi resonances between a fundamental and combination band are observed. The electrostatic potential map of fluoroformate reveals substantial charge density on fluorine as well as on the oxygen atoms, suggesting multiple sites for interaction with hydrogen bond donors and electrophiles, which may in turn lead to intriguing solvation structures and reaction pathways.

Relationship between ion pair geometries and electrostatic strengths in proteins.

PubMed Central

Kumar, Sandeep; Nussinov, Ruth

2002-01-01

The electrostatic free energy contribution of an ion pair in a protein depends on two factors, geometrical orientation of the side-chain charged groups with respect to each other and the structural context of the ion pair in the protein. Conformers in NMR ensembles enable studies of the relationship between geometry and electrostatic strengths of ion pairs, because the protein structural contexts are highly similar across different conformers. We have studied this relationship using a dataset of 22 unique ion pairs in 14 NMR conformer ensembles for 11 nonhomologous proteins. In different NMR conformers, the ion pairs are classified as salt bridges, nitrogen-oxygen (N-O) bridges and longer-range ion pairs on the basis of geometrical criteria. In salt bridges, centroids of the side-chain charged groups and at least a pair of side-chain nitrogen and oxygen atoms of the ion-pairing residues are within a 4 A distance. In N-O bridges, at least a pair of the side-chain nitrogen and oxygen atoms of the ion-pairing residues are within 4 A distance, but the distance between the side-chain charged group centroids is greater than 4 A. In the longer-range ion pairs, the side-chain charged group centroids as well as the side-chain nitrogen and oxygen atoms are more than 4 A apart. Continuum electrostatic calculations indicate that most of the ion pairs have stabilizing electrostatic contributions when their side-chain charged group centroids are within 5 A distance. Hence, most (approximately 92%) of the salt bridges and a majority (68%) of the N-O bridges are stabilizing. Most (approximately 89%) of the destabilizing ion pairs are the longer-range ion pairs. In the NMR conformer ensembles, the electrostatic interaction between side-chain charged groups of the ion-pairing residues is the strongest for salt bridges, considerably weaker for N-O bridges, and the weakest for longer-range ion pairs. These results suggest empirical rules for stabilizing electrostatic interactions in proteins. PMID:12202384

Ion Trap Array-Based Systems And Methods For Chemical Analysis

DOEpatents

Whitten, William B [Oak Ridge, TN; Ramsey, J Michael [Knoxville, TN

2005-08-23

An ion trap-based system for chemical analysis includes an ion trap array. The ion trap array includes a plurality of ion traps arranged in a 2-dimensional array for initially confining ions. Each of the ion traps comprise a central electrode having an aperture, a first and second insulator each having an aperture sandwiching the central electrode, and first and second end cap electrodes each having an aperture sandwiching the first and second insulator. A structure for simultaneously directing a plurality of different species of ions out from the ion traps is provided. A spectrometer including a detector receives and identifies the ions. The trap array can be used with spectrometers including time-of-flight mass spectrometers and ion mobility spectrometers.

Radon detection

DOEpatents

MacArthur, D.W.; Allander, K.S.; Bounds, J.A.

1994-01-25

A detector for atmospheric radon using a long range alpha detector as its sensing element is described. An electrostatic filter removes ions from ambient air, while allowing radon atoms to pass into a decay cavity. Here, radon atoms are allowed to decay, creating air ions. These air ions are drawn by a fan through a second electrostatic filter which can be activated or deactivated, and into the long range alpha detector. With the second electrostatic filter activated, no air ions are allowed to pass, and the signal output from the long range alpha detector consists of only the electronic background. With the second electrostatic filter deactivated, air ions and cosmic rays will be detected. The cosmic ray contribution can be minimized by shielding. 3 figures.

Radon detection

DOEpatents

MacArthur, Duncan W.; Allander, Krag S.; Bounds, John A.

1994-01-01

A detector for atmospheric radon using a long range alpha detector as its sensing element. An electrostatic filter removes ions from ambient air, while allowing radon atoms to pass into a decay cavity. Here, radon atoms are allowed to decay, creating air ions. These air ions are drawn by a fan through a second electrostatic filter which can be activated or deactivated, and into the long range alpha detector. With the second electrostatic filter activated, no air ions are allowed to pass, and the signal output from the long range alpha detector consists of only the electronic background. With the second electrostatic filter deactivated, air ions and cosmic rays will be detected. The cosmic ray contribution can be minimized by shielding.

Microfabricated linear Paul-Straubel ion trap

DOEpatents

Mangan, Michael A [Albuquerque, NM; Blain, Matthew G [Albuquerque, NM; Tigges, Chris P [Albuquerque, NM; Linker, Kevin L [Albuquerque, NM

2011-04-19

An array of microfabricated linear Paul-Straubel ion traps can be used for mass spectrometric applications. Each ion trap comprises two parallel inner RF electrodes and two parallel outer DC control electrodes symmetric about a central trap axis and suspended over an opening in a substrate. Neighboring ion traps in the array can share a common outer DC control electrode. The ions confined transversely by an RF quadrupole electric field potential well on the ion trap axis. The array can trap a wide array of ions.

Electrostatic trapping as a key to the dynamics of plasmas, fluids and other collective systems [review article

NASA Astrophysics Data System (ADS)

Luque, A.; Schamel, H.

2005-08-01

This review article focusses on the phenomenon of collective particle trapping in dilute plasmas and related fluid-like systems. A coherent electrostatic wave or fluctuation, being excited by some mechanism in a plasma, is able to trap collectively charged particles in its potential trough(s) with the ultimate feedback of stabilizing and manipulating the original cause of growth. This phenomenon is well-known from particle simulations of a current-driven two-stream instability and its subsequent quenching by particle trapping. But also the nonlinear Landau damping process resulting in a BGK-like (Bernstein, Green, Kruskal) trapped particle mode sets an example. However, as shown in this report, already a slightly driven plasma has many possibilities of generating trapped particle modes-the mentioned cases representing only two examples-through which it generally becomes nonlinearly unstable. A direct consequence of this feedback of particle trapping is that the macroscopic (dielectric) properties of such a structured plasma may have changed fundamentally such that the relationship to what is known from linear wave theory is lost. We, hence, have to deal with a nonlinear kinetic description which, in case of a collisionless, electrostatic plasma, is the Vlasov-Poisson description. The present report is devoted to a large extent to a 1D Vlasov-Poisson system but also consequences for other physical systems will be derived and mentioned. These and other findings will be developed in some detail culminating in a new paradigm for plasma stability which says: a current-carrying plasma is nonlinearly unstable in a much wider region of parameter space than predicted by linear wave theory with the consequence that the associated turbulence and anomalous transport are triggered much easier than suggested by standard linear wave analysis. Responsible for this new scenario are localized trapped particle modes-more specifically electron and ion holes of zero or negative energy-which are found to be excited well below the threshold of linear instability. In other words, a current-driven plasma shows a much larger sensibility to fluctuations than thought before and described in textbooks. The analysis presented reveals that a plasma, becoming structured by the generation of such modes, resides in a lower free energy state than the one without structures, being therefore in a preferred state that acts as an attractor in the system. Holes having this property will be briefly called negative energy holes (NEHs). For example, zero or negative energy ion holes are found to exist for any drift velocity between electrons and ions and for any temperature ratio. Two independent codes, a Vlasov-code and a PIC-(particle in cell)code, are used to approve this new scenario of instability. Moreover, by adding a Fokker-Planck collision term to the Vlasov-code, holes are shown to resist weak collisions, turn out to be robust and not only found in purely collisionless plasmas and cause an increase of resistivity. A natural outcome of this scenario, therefore, is that whenever free (kinetic) energy is available, holes (and double layers) are necessarily excited, penetrating intermittently the plasma. Satellite measurements, yielding holes and double layers as the most omnipresent structures found in space, provide a typical example. Having investigated classical plasmas this way, we show that many of these innovations can be transferred to other systems, as well. First, we perform a quantum-correction to electron holes by using the Wigner-Moyal description of quantum mechanics in phase-space. As a result we get a weakening of the hole for which tunneling of particles across the separatrix of the unperturbed, deterministic classical hole equilibrium is responsible. The formalism is then used to find a link between hole structures in classical plasmas and envelope solitons in nonlinear optical media. This gives rise to a new approximation method for wave envelope solutions of the nonlinear Schrödinger equation, which utilizes quasi-particle trapping and may be valuable in cases of nonlinearties for which a direct solution is missing. Another important application are particle beams in circular accelerators and storage rings. We prove analytically the existence of localized and periodic structures in coasting beams, as have been found experimentally for instance at Fermilab and at CERN, which are quite analogous to holes in classical plasmas. We also present an improved criterion for focusing. For bunched beams we describe and apply an iterative numerical procedure to find solitary hump and hole structures superimposed on the particle bunch, the former of which having been found recently in the Relativistic Hadron-Ion Collider (RHIC) at Brookhaven. Finally, we stress the mathematical equivalence between the 1D Vlasov-Poisson system and the equations describing a 2D incompressible, ideal fluid or the perpendicular dynamics of a strongly magnetized plasma in fluid or MHD approximation and other more complex fluids, such as rotating fluids, inhomogeneous plasmas, etc. This implies that tiny fluid elements trapped in coherent patches of shear flow motion, such as in secondary (tertiary) states that govern the transition to turbulence in ordinary hydrodynamics, do play a similar role than trapped particles in electrostatic waves, violating any linear wave ansatz. Or, said in different words, whenever a continues spectrum arises in a linearized fluid-like system associated with singular perturbations and a resonance between (quasi-)particles and the field, one has to consider this as a hint that the neglect of nonlinearity is not justified and that nonlinear wave solutions have to be taken into account in describing the evolution of the system correctly. This statement holds true already at an infinitesimal energy level of the coherent perturbations. Nonlinearity, and with it trapping structures, turns out to be a necessary requisite in all stages of the dynamical evolution not only at finite wave amplitudes, as commonly believed. In conclusion, in this report we emphasize the importance of collective trapping in (nearly) ideal plasmas and related systems bringing in at any level of wave activity a fundamental nonlinearity which is missed in standard linear wave theories as described in textbooks. The associated trapped particle modes challenge standard flow theories playing a key role in the interpretation of turbulence and anomalous transport.

In situ plasma removal of surface contaminants from ion trap electrodes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Haltli, Raymond A.

2015-05-01

In this thesis, the construction and implementation of an in situ plasma discharge designed to remove surface contaminants from electrodes in an ion trapping experimental system is presented with results. In recent years, many advances have been made in using ion traps for quantum information processing. All of the criteria defined by DiVincenzo for using ion traps for implementing a quantum computer have been individually demonstrated, and in particular surface traps provide a scalable platform for ions. In order to be used for quantum algorithms, trapped ions need to be cooled to their motional (quantum mechanical) ground state. One ofmore » the hurdles in integrating surface ion traps for a quantum computer is minimizing electric field noise, which causes the ion to heat out of its motional ground state and which increases with smaller ion-to-electrode distances realized with surface traps. Surface contamination of trap electrodes is speculated to be the primary source of electric field noise. The main goal achieved by this work was to implement an in situ surface cleaning solution for surface electrode ion traps, which would not modify the ion trap electrode surface metal. Care was taken in applying the RF power in order to localize a plasma near the trap electrodes. A method for characterizing the energy of the plasma ions arriving at the ion trap surface is presented and results for plasma ion energies are shown. Finally, a method for quantifying the effectiveness of plasma cleaning of trap electrodes, using the surface analysis technique of X-ray photoelectron spectroscopy for measuring the amount and kind of surface contaminants, is described. A significant advantage of the trap electrode surface cleaning method presented here is the minimal changes necessary for implementation on a working ion trap experimental system.« less

An Optical Trap for Relativistic Plasma

NASA Astrophysics Data System (ADS)

Zhang, Ping

2002-11-01

Optical traps have achieved remarkable success recently in confining ultra-cold matter.Traps capable of confining ultra-hot matter, or plasma, have also been built for applications such as basic plasma research and thermonuclear fusion. For instance, low-density plasmas with temperature less than 1 keV have been confined with static magnetic fields in Malmberg-Penning traps. Low-density 10-50 keV plasmas are confined in magnetic mirrors and tokamaks. High density plasmas have been trapped in optical traps with kinetic energies up to 10 keV [J. L. Chaloupka and D. D. Meyerhofer, Phys. Rev. Lett. 83, 4538 (1999)]. We present the results of experiment, theory and numerical simulation on an optical trap capable of confining relativistic plasma. A stationary interference grating with submicron spacing is created when two high-power (terawatt) laser pulses of equal wavelength (1-micron) are focused from orthogonal directions to the same point in space and time in high density underdense plasma. Light pressure gradients bunch electrons into sheets located at the minima of the interference pattern. The density of the bunched electrons is found to be up to ten times the background density, which is orders-of-magnitude above that previously reported for other optical traps or plasma waves. The amplitudes and frequencies of multiple satellites in the scattered spectrum also indicate the presence of a highly nonlinear ion wave and an electron temperature about 100 keV. Energy transfer from the stronger beam to the weaker beam is also observed. Potential applications include a test-bed for detailed studies of relativistic nonlinear scattering, a positron source and an electrostatic wiggler. This research is also relevant to fast igniter fusion or ion acceleration experiments, in which laser pulses with intensities comparable to those used in the experiment may also potentially beat [Y. Sentoku, et al., Appl. Phys. B 74, 207215 (2002)]. The details of a specific application, the injection of electrons into laser-driven plasma waves, will also be presented. With crossed beams, the energy of a laser-accelerated electron beam is increased and its emittance is decreased compared with a single beam, potentially paving the way towards an all-optical monoenergetic electron injector.

Electrostatic effects on clustering and ion dynamics in ionomer melts

NASA Astrophysics Data System (ADS)

Ma, Boran; Nguyen, Trung; Pryamitsyn, Victor; Olvera de La Cruz, Monica

An understanding of the relationships between ionomer chain morphology, dynamics and counter-ion mobility is a key factor in the design of ion conducting membranes for battery applications. In this study, we investigate the influence of electrostatic coupling between randomly charged copolymers (ionomers) and counter ions on the structural and dynamic features of a model system of ionomer melts. Using coarse-grained molecular dynamics (CGMD) simulations, we found that variations in electrostatic coupling strength (Γ) remarkably affect the formation of ion-counter ion clusters, ion mobility, and polymer dynamics for a range of charged monomer fractions. Specifically, an increase in Γ leads to larger ionic cluster sizes and reduced polymer and ion mobility. Analysis of the distribution of the radius of gyration of the clusters further reveals that the fractal dimension of the ion clusters is nearly independent from Γ for all the cases studied. Finally, at sufficiently high values of Γ, we observed arrested heterogeneous ions mobility, which is correlated with an increase in ion cluster size. These findings provide insight into the role of electrostatics in governing the nanostructures formed by ionomers.

Ion trap architectures and new directions

NASA Astrophysics Data System (ADS)

Siverns, James D.; Quraishi, Qudsia

2017-12-01

Trapped ion technology has seen advances in performance, robustness and versatility over the last decade. With increasing numbers of trapped ion groups worldwide, a myriad of trap architectures are currently in use. Applications of trapped ions include: quantum simulation, computing and networking, time standards and fundamental studies in quantum dynamics. Design of such traps is driven by these various research aims, but some universally desirable properties have lead to the development of ion trap foundries. Additionally, the excellent control achievable with trapped ions and the ability to do photonic readout has allowed progress on quantum networking using entanglement between remotely situated ion-based nodes. Here, we present a selection of trap architectures currently in use by the community and present their most salient characteristics, identifying features particularly suited for quantum networking. We also discuss our own in-house research efforts aimed at long-distance trapped ion networking.

Recent Developments in Microwave Ion Clocks

NASA Astrophysics Data System (ADS)

Prestage, John D.; Tjoelker, Robert L.; Maleki, Lute

We review the development of microwave-frequency standards based on trapped ions. Following two distinct paths, microwave ion clocks have evolved greatly in the last twenty years since the earliest Paul-trap-based units. Laser-cooled ion frequency standards reduce the second-order Doppler shift from ion micromotion and thermal secular motion achieving good signal-to-noise ratios via cycling transitions where as many as ~10^8 photons per second per ion may be scattered. Today, laser-cooled ion standards are based on linear Paul traps which hold ions near the node line of the trapping electric field, minimizing micromotion at the trapping-field frequency and the consequent second-order Doppler frequency shift. These quadrupole (radial) field traps tightly confine tens of ions to a crystalline single-line structure. As more ions are trapped, space charge forces some ions away from the node-line axis and the second-order Doppler effect grows larger, even at negligibly small secular temperatures. Buffer-gas-cooled clocks rely on large numbers of ions, typically ~10^7, optically pumped by a discharge lamp at a scattering rate of a few photons per second per ion. To reduce the second-order Doppler shift from space charge repulsion of ions from the trap node line, novel multipole ion traps are now being developed where ions are weakly bound with confining fields that are effectively zero through the trap interior and grow rapidly near the trap electrode ``walls''.

Dispersion equation for electrostatic ion cyclotron instability under the effect of ionization in a dusty plasma

NASA Astrophysics Data System (ADS)

Singh, Sukhmander

2018-05-01

In the present paper we derive the plasma dispersion equation under the effect of ionization rate in a dust plasma to investigate the electrostatic ion cyclotron instability, where dust charge fluctuation is absent. It has one of the lowest threshold drift velocities among all the current-driven instabilities in isothermal plasma. The Electrostatic ion cyclotron instability in a dusty plasma containing electrons, light ions, and massive negatively charged dust grains which can be investigated both experimentally and theoretically.

Coaxial ion trap mass spectrometer: concentric toroidal and quadrupolar trapping regions.

PubMed

Peng, Ying; Hansen, Brett J; Quist, Hannah; Zhang, Zhiping; Wang, Miao; Hawkins, Aaron R; Austin, Daniel E

2011-07-15

We present the design and results for a new radio-frequency ion trap mass analyzer, the coaxial ion trap, in which both toroidal and quadrupolar trapping regions are created simultaneously. The device is composed of two parallel ceramic plates, the facing surfaces of which are lithographically patterned with concentric metal rings and covered with a thin film of germanium. Experiments demonstrate that ions can be trapped in either region, transferred from the toroidal to the quadrupolar region, and mass-selectively ejected from the quadrupolar region to a detector. Ions trapped in the toroidal region can be transferred to the quadrupole region using an applied ac signal in the radial direction, although it appears that the mechanism of this transfer does not involve resonance with the ion secular frequency, and the process is not mass selective. Ions in the quadrupole trapping region are mass analyzed using dipole resonant ejection. Multiple transfer steps and mass analysis scans are possible on a single population of ions, as from a single ionization/trapping event. The device demonstrates better mass resolving power than the radially ejecting halo ion trap and better sensitivity than the planar quadrupole ion trap.

Electro-osmosis over inhomogeneously charged surfaces in presence of non-electrostatic ion-ion interactions

NASA Astrophysics Data System (ADS)

Ghosh, Uddipta; Chakraborty, Suman

2016-06-01

In this study, we attempt to bring out a generalized formulation for electro-osmotic flows over inhomogeneously charged surfaces in presence of non-electrostatic ion-ion interactions. To this end, we start with modified electro-chemical potential of the individual species and subsequently use it to derive modified Nernst-Planck equation accounting for the ionic fluxes generated because of the presence of non-electrostatic potential. We establish what we refer to as the Poisson-Helmholtz-Nernst-Planck equations, coupled with the Navier-Stokes equations, to describe the complete transport process. Our analysis shows that the presence of non-electrostatic interactions between the ions results in an excess body force on the fluid, and modifies the osmotic pressure as well, which has hitherto remained unexplored. We further apply our analysis to a simple geometry, in an effort to work out the Smoluchowski slip velocity for thin electrical double layer limits. To this end, we employ singular perturbation and develop a general framework for the asymptotic analysis. Our calculations reveal that the final expression for slip velocity remains the same as that without accounting for non-electrostatic interactions. However, the presence of non-electrostatic interactions along with ion specificity can significantly change the quantitative behavior of Smoluchowski slip velocity. We subsequently demonstrate that the presence of non-electrostatic interactions may significantly alter the effective interfacial potential, also termed as the "Zeta potential." Our analysis can potentially act as a guide towards the prediction and possibly quantitative determination of the implications associated with the existence of non-electrostatic potential, in an electrokinetic transport process.

Investigation of electrostatic waves in the ion cyclotron range of frequencies in L-4 and ACT-1

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ono, Masayuki

Electrostatic waves in the ion cyclotron range of frequencies (ICRF) were studied in the Princeton L-4 and ACT-1 devices for approximately ten years, from 1975 to 1985. The investigation began in the L-4 linear device, looking for the parametric excitation of electrostatic ion cyclotron waves in multi-ion-species plasmas. In addition, this investigation verified multi-ion-species effects on the electrostatic ion cyclotron wave dispersion religion including the ion-ion hybrid resonance. Finite-Larmor-radius modification of the wave dispersion relation was also observed, even for ion temperatures of T{sub i} {approx} 1/40 eV. Taking advantage of the relatively high field and long device length ofmore » L-4, the existence of the cold electrostatic ion cyclotron wave (CES ICW) was verified. With the arrival of the ACT-1 toroidal device, finite-Larmor-radius (FLR) waves were studied in a relatively collisionless warm-ion hydrogen plasma. Detailed investigations of ion Bernstein waves (IBW) included the verification of mode-transformation in their launching, their wave propagation characteristics, their absorption, and the resulting ion heating. This basic physics activity played a crucial role in developing a new reactor heating concept termed ion Bernstein wave heating. Experimental research in the lower hybrid frequency range confirmed the existence of FLR effects near the lower hybrid resonance, predicted by Stix in 1965. In a neon plasma with a carefully placed phased wave exciter, the neutralized ion Bernstein wave was observed for the first time. Using a fastwave ICRF antenna, two parasitic excitation processes for IBW -- parametric instability and density-gradient-driven excitation -- were also discovered. In the concluding section of this paper, a possible application of externally launched electrostatic waves is suggested for helium ash removal from fusion reactor plasmas.« less

Investigation of electrostatic waves in the ion cyclotron range of frequencies in L-4 and ACT-1

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ono, Masayuki.

Electrostatic waves in the ion cyclotron range of frequencies (ICRF) were studied in the Princeton L-4 and ACT-1 devices for approximately ten years, from 1975 to 1985. The investigation began in the L-4 linear device, looking for the parametric excitation of electrostatic ion cyclotron waves in multi-ion-species plasmas. In addition, this investigation verified multi-ion-species effects on the electrostatic ion cyclotron wave dispersion religion including the ion-ion hybrid resonance. Finite-Larmor-radius modification of the wave dispersion relation was also observed, even for ion temperatures of T[sub i] [approx] 1/40 eV. Taking advantage of the relatively high field and long device length ofmore » L-4, the existence of the cold electrostatic ion cyclotron wave (CES ICW) was verified. With the arrival of the ACT-1 toroidal device, finite-Larmor-radius (FLR) waves were studied in a relatively collisionless warm-ion hydrogen plasma. Detailed investigations of ion Bernstein waves (IBW) included the verification of mode-transformation in their launching, their wave propagation characteristics, their absorption, and the resulting ion heating. This basic physics activity played a crucial role in developing a new reactor heating concept termed ion Bernstein wave heating. Experimental research in the lower hybrid frequency range confirmed the existence of FLR effects near the lower hybrid resonance, predicted by Stix in 1965. In a neon plasma with a carefully placed phased wave exciter, the neutralized ion Bernstein wave was observed for the first time. Using a fastwave ICRF antenna, two parasitic excitation processes for IBW -- parametric instability and density-gradient-driven excitation -- were also discovered. In the concluding section of this paper, a possible application of externally launched electrostatic waves is suggested for helium ash removal from fusion reactor plasmas.« less

Evolution of Orbitrap Mass Spectrometry Instrumentation

NASA Astrophysics Data System (ADS)

Eliuk, Shannon; Makarov, Alexander

2015-07-01

We discuss the evolution of OrbitrapTM mass spectrometry (MS) from its birth in the late 1990s to its current role as one of the most prominent techniques for MS. The Orbitrap mass analyzer is the first high-performance mass analyzer that employs trapping of ions in electrostatic fields. Tight integration with the ion injection process enables the high-resolution, mass accuracy, and sensitivity that have become essential for addressing analytical needs in numerous areas of research, as well as in routine analysis. We examine three major families of instruments (related to the LTQ Orbitrap, Q Exactive, and Orbitrap Fusion mass spectrometers) in the context of their historical development over the past ten eventful years. We discuss as well future trends and perspectives of Orbitrap MS. We illustrate the compelling potential of Orbitrap-based mass spectrometers as (ultra) high-resolution platforms, not only for high-end proteomic applications, but also for routine targeted analysis.

Lab-on-a-Chip Sensor for Monitoring Perchlorate in Ground and Surface Water

DTIC Science & Technology

2012-02-01

uses zwitterionic surfactants was immobilized on either a conventional or membrane-based stationary phase (electrostatic ion chromatography ) em...substantially higher than that of drinking water. A novel extraction method incorporat- ing the fundamentals of electrostatic ion chromatography (EIC) was...electrostatic ion chromatography (EIC), is presented as a way to overcome this challenge. Two extraction formats, employing either a packed bed or a monolith

Systems and Methods for Ejection of Ions from an Ion Trap

NASA Technical Reports Server (NTRS)

Cooks, Robert Graham (Inventor); Snyder, Dalton (Inventor)

2018-01-01

The invention generally relates to systems and methods for ejection of ions from an ion trap. In certain embodiments, systems and methods of the invention sum two different frequency signals into a single summed signal that is applied to an ion trap. In other embodiments, an amplitude of a single frequency signal is modulated as the single frequency signal is being applied to the ion trap. In other embodiments, a first alternating current (AC) signal is applied to an ion trap that varies as a function of time, while a constant radio frequency (RF) signal is applied to the ion trap.

Power matching between plasma generation and electrostatic acceleration in helicon electrostatic thruster

NASA Astrophysics Data System (ADS)

Ichihara, D.; Nakagawa, Y.; Uchigashima, A.; Iwakawa, A.; Sasoh, A.; Yamazaki, T.

2017-10-01

The effects of a radio-frequency (RF) power on the ion generation and electrostatic acceleration in a helicon electrostatic thruster were investigated with a constant discharge voltage of 300 V using argon as the working gas at a flow rate either of 0.5 Aeq (Ampere equivalent) or 1.0 Aeq. A RF power that was even smaller than a direct-current (DC) discharge power enhanced the ionization of the working gas, thereby both the ion beam current and energy were increased. However, an excessively high RF power input resulted in their saturation, leading to an unfavorable increase in an ionization cost with doubly charged ion production being accompanied. From the tradeoff between the ion production by the RF power and the electrostatic acceleration made by the direct current discharge power, the thrust efficiency has a maximum value at an optimal RF to DC discharge power ratio of 0.6 - 1.0.

Status and outlook of CHIP-TRAP: The Central Michigan University high precision Penning trap

NASA Astrophysics Data System (ADS)

Redshaw, M.; Bryce, R. A.; Hawks, P.; Gamage, N. D.; Hunt, C.; Kandegedara, R. M. E. B.; Ratnayake, I. S.; Sharp, L.

2016-06-01

At Central Michigan University we are developing a high-precision Penning trap mass spectrometer (CHIP-TRAP) that will focus on measurements with long-lived radioactive isotopes. CHIP-TRAP will consist of a pair of hyperbolic precision-measurement Penning traps, and a cylindrical capture/filter trap in a 12 T magnetic field. Ions will be produced by external ion sources, including a laser ablation source, and transported to the capture trap at low energies enabling ions of a given m / q ratio to be selected via their time-of-flight. In the capture trap, contaminant ions will be removed with a mass-selective rf dipole excitation and the ion of interest will be transported to the measurement traps. A phase-sensitive image charge detection technique will be used for simultaneous cyclotron frequency measurements on single ions in the two precision traps, resulting in a reduction in statistical uncertainty due to magnetic field fluctuations.

Suppressing Loss of Ions in an Atomic Clock

NASA Technical Reports Server (NTRS)

Prestage, John; Chung, Sang

2010-01-01

An improvement has been made in the design of a compact, highly stable mercury- ion clock to suppress a loss of ions as they are transferred between the quadrupole and higher multipole ion traps. Such clocks are being developed for use aboard spacecraft for navigation and planetary radio science. The modification is also applicable to ion clocks operating on Earth: indeed, the success of the modification has been demonstrated in construction and operation of a terrestrial breadboard prototype of the compact, highly stable mercury-ion clock. Selected aspects of the breadboard prototype at different stages of development were described in previous NASA Tech Briefs articles. The following background information is reviewed from previous articles: In this clock as in some prior ion clocks, mercury ions are shuttled between two ion traps, one a 16- pole linear radio-frequency trap, while the other is a quadrupole radio-frequency trap. In the quadrupole trap, ions are tightly confined and optical state selection from a 202Hg lamp is carried out. In the 16-pole trap, the ions are more loosely confined and atomic transitions are interrogated by use of a microwave beam at approximately 40.507 GHz. The trapping of ions effectively eliminates the frequency pulling that would otherwise be caused by collisions between clock atoms and the wall of a gas cell. The shuttling of the ions between the two traps enables separation of the state-selection process from the clock microwave-resonance process, so that each of these processes can be optimized independently of the other. This is similar to the operation of an atomic beam clock, except that with ions the beam can be halted and reversed as ions are shuttled back and forth between the two traps. When the two traps are driven at the same radio frequency, the strength of confinement can be reduced near the junction between the two traps, depending upon the relative phase of the RF voltage used to operate each of the two traps, and can cause loss of ions during each transit between the traps and thereby cause loss of the 40.507-GHz ion-clock resonance signal. The essence of the modification is to drive the two traps at different frequencies typically between 1.5 and 2 MHz for the quadrupole trap and a frequency a few hundred kHz higher for the 16- pole trap. A frequency difference of a few hundred kHz ensures that the ion motion caused by the trapping electric fields is small relative to the diameter of the traps. Unlike in the case in which both traps are driven at the same frequency, the trapping electric fields near the junction are not zero at all times; instead, the regions of low electric field near the junction open and close at the difference frequency. An additional benefit of making the 16-pole trap operate at higher frequency is that the strength or depth of the multipole trap can be increased independent of the quadrupole ion trap.

Wave-Kinetic Simulations of the Nonlinear Generation of Electromagnetic VLF Waves through Velocity Ring Instabilities

NASA Astrophysics Data System (ADS)

Ganguli, G.; Crabtree, C. E.; Rudakov, L.; Mithaiwala, M.

2014-12-01

Velocity ring instabilities are a common naturally occuring magnetospheric phenomenon that can also be generated by man made ionospheric experiments. These instabilities are known to generate lower-hybrid waves, which generally cannot propagte out of the source region. However, nonlinear wave physics can convert these linearly driven electrostatic lower-hybrid waves into electromagnetic waves that can escape the source region. These nonlinearly generated waves can be an important source of VLF turbulence that controls the trapped electron lifetime in the radiation belts. We develop numerical solutions to the wave-kinetic equation in a periodic box including the effects of nonlinear (NL) scattering (nonlinear Landau damping) of Lower-hybrid waves giving the evolution of the wave-spectra in wavenumber space. Simultaneously we solve the particle diffusion equation of both the background plasma particles and the ring ions, due to both linear and nonlinear Landau resonances. At initial times for cold ring ions, an electrostatic beam mode is excited, while the kinetic mode is stable. As the instability progresses the ring ions heat, the beam mode is stabilized, and the kinetic mode destabilizes. When the amplitude of the waves becomes sufficient the lower-hybrid waves are scattered (by either nearly unmagnetized ions or magnetized electrons) into electromagnetic magnetosonic waves [Ganguli et al 2010]. The effect of NL scattering is to limit the amplitude of the waves, slowing down the quasilinear relaxation time and ultimately allowing more energy from the ring to be liberated into waves [Mithaiwala et al. 2011]. The effects of convection out of the instability region are modeled, additionally limiting the amplitude of the waves, allowing further energy to be liberated from the ring [Scales et al., 2012]. Results are compared to recent 3D PIC simulations [Winske and Duaghton 2012].

Eliminating degradation and uncovering ion-trapping dynamics in electrochromic WO3 thin films

PubMed Central

Wen, Rui-Tao; Granqvist, Claes G.; Niklasson, Gunnar A.

2015-01-01

Amorphous WO3 thin films are of keen interest as cathodic electrodes in transmittance-modulating electrochromic devices. However, these films suffer from ion-trapping-induced degradation of optical modulation and reversibility upon extended Li+-ion exchange. Here, we demonstrate that ion-trapping-induced degradation, which is commonly believed to be irreversible, can be successfully eliminated by constant-current-driven de-trapping, i.e., WO3 films can be rejuvenated and regain their initial highly reversible electrochromic performance. Pronounced ion-trapping occurs when x exceeds ~0.65 in LixWO3 during ion insertion. We find two main kinds of Li+-ion trapping sites (intermediate and deep) in WO3, where the intermediate ones are most prevalent. Li+-ions can be completely removed from intermediate traps but are irreversibly bound in deep traps. Our results provide a general framework for developing and designing superior electrochromic materials and devices. PMID:26259104

Generating electrospray from microchip devices using electroosmotic pumping

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ramsey, R.S.; Ramsey, J.M.

1997-03-15

A method of generating electrospray from solutions emerging from small channels etched on planer substrates in described. The fluids are delivered using electroosmotically induced pressures and are sprayed electrostatically from the terminus of a channel by applying an electrical potential of sufficient amplitude to generate the electrospray between the microchip and a conductor spaced from the channel terminus. No major modification of the microchip is required other than to expose a channel opening. The principles that regulate the fluid delivery are described and demonstrated. A spectrum for a test compound, tetrabutylammonium iodide, that was continuously electrophoresed was obtained by couplingmore » the microchip to an ion trap mass spectrometer. 35 refs., 6 figs.« less

Microfabricated ion trap array

DOEpatents

Blain, Matthew G [Albuquerque, NM; Fleming, James G [Albuquerque, NM

2006-12-26

A microfabricated ion trap array, comprising a plurality of ion traps having an inner radius of order one micron, can be fabricated using surface micromachining techniques and materials known to the integrated circuits manufacturing and microelectromechanical systems industries. Micromachining methods enable batch fabrication, reduced manufacturing costs, dimensional and positional precision, and monolithic integration of massive arrays of ion traps with microscale ion generation and detection devices. Massive arraying enables the microscale ion traps to retain the resolution, sensitivity, and mass range advantages necessary for high chemical selectivity. The reduced electrode voltage enables integration of the microfabricated ion trap array with on-chip circuit-based rf operation and detection electronics (i.e., cell phone electronics). Therefore, the full performance advantages of the microfabricated ion trap array can be realized in truly field portable, handheld microanalysis systems.

A Superconducting Magnet UCN Trap for Precise Neutron Lifetime Measurements.

PubMed

Picker, R; Altarev, I; Bröcker, J; Gutsmiedl, E; Hartmann, J; Müller, A; Paul, S; Schott, W; Trinks, U; Zimmer, O

2005-01-01

Finite-element methods along with Monte Carlo simulations were used to design a magnetic storage device for ultracold neutrons (UCN) to measure their lifetime. A setup was determined which should make it possible to confine UCN with negligible losses and detect the protons emerging from β-decay with high efficiency: stacked superconducting solenoids create the magnetic storage field, an electrostatic extraction field inside the storage volume assures high proton collection efficiency. Alongside with the optimization of the magnetic and electrostatic design, the properties of the trap were investigated through extensive Monte Carlo simulation.

An electrostatic glass actuator for ultrahigh vacuum: A rotating light trap for continuous beams of laser-cooled atoms.

PubMed

Füzesi, F; Jornod, A; Thomann, P; Plimmer, M D; Dudle, G; Moser, R; Sache, L; Bleuler, H

2007-10-01

This article describes the design, characterization, and performance of an electrostatic glass actuator adapted to an ultrahigh vacuum environment (10(-8) mbar). The three-phase rotary motor is used to drive a turbine that acts as a velocity-selective light trap for a slow continuous beam of laser-cooled atoms. This simple, compact, and nonmagnetic device should find applications in the realm of time and frequency metrology, as well as in other areas of atomic, molecular physics and elsewhere.

Measuring forces and dynamics for optically levitated 20μm PS particles in air using electrostatic modulation

NASA Astrophysics Data System (ADS)

Park, Haesung; LeBrun, Thomas W.

2015-08-01

We demonstrate the simultaneous measurement of optical trap stiffness and quadrant-cell photodetector (QPD) calibration of optically trapped polystyrene particle in air. The analysis is based on the transient response of particles, confined to an optical trap, subject to a pulsed electrostatic field generated by parallel indium tin oxide (ITO) coated substrates. The resonant natural frequency and damping were directly estimated by fitting the analytical solution of the transient response of an underdamped harmonic oscillator to the measured particle displacement from its equilibrium position. Because, the particle size was estimated independently with video microscopy, this approach allowed us to measure the optical force without ignoring the effects of inertia and temperature changes from absorption.

On the Impact of Electrostatic Correlations on the Double-Layer Polarization of a Spherical Particle in an Alternating Current Field.

PubMed

Alidoosti, Elaheh; Zhao, Hui

2018-05-15

At concentrated electrolytes, the ion-ion electrostatic correlation effect is considered an important factor in electrokinetics. In this paper, we compute, in theory and simulation, the dipole moment for a spherical particle (charged, dielectric) under the action of an alternating electric field using the modified continuum Poisson-Nernst-Planck (PNP) model by Bazant et al. [ Double Layer in Ionic Liquids: Overscreening Versus Crowding . Phys. Rev. Lett. 2011 , 106 , 046102 ] We investigate the dependency of the dipole moment in terms of frequency and its variation with such quantities like ζ-potential, electrostatic correlation length, and double-layer thickness. With thin electric double layers, we develop simple models through performing an asymptotic analysis of the modified PNP model. We also present numerical results for an arbitrary Debye screening length and electrostatic correlation length. From the results, we find a complicated impact of electrostatic correlations on the dipole moment. For instance, with increasing the electrostatic correlation length, the dipole moment decreases and reaches a minimum and then it goes up. This is because of initially decreasing of surface conduction and finally increasing due to the impact of ion-ion electrostatic correlations on ion's convection and migration. Also, we show that in contrast to the standard PNP model, the modified PNP model can qualitatively explain the data from the experimental results in multivalent electrolytes.

Ion traps for precision experiments at rare-isotope-beam facilities

NASA Astrophysics Data System (ADS)

Kwiatkowski, Anna

2016-09-01

Ion traps first entered experimental nuclear physics when the ISOLTRAP team demonstrated Penning trap mass spectrometry of radionuclides. From then on, the demand for ion traps has grown at radioactive-ion-beam (RIB) facilities since beams can be tailored for the desired experiment. Ion traps have been deployed for beam preparation, from bunching (thereby allowing time coincidences) to beam purification. Isomerically pure beams needed for nuclear-structure investigations can be prepared for trap-assisted or in-trap decay spectroscopy. The latter permits studies of highly charged ions for stellar evolution, which would be impossible with traditional experimental nuclear-physics methods. Moreover, the textbook-like conditions and advanced ion manipulation - even of a single ion - permit high-precision experiments. Consequently, the most accurate and precise mass measurements are now performed in Penning traps. After a brief introduction to ion trapping, I will focus on examples which showcase the versatility and utility of the technique at RIB facilities. I will demonstrate how this atomic-physics technique has been integrated into nuclear science, accelerator physics, and chemistry. DOE.

Mobility-Selected Ion Trapping and Enrichment Using Structures for Lossless Ion Manipulations

DOE PAGES

Chen, Tsung-Chi; Ibrahim, Yehia M.; Webb, Ian K.; ...

2016-01-11

The integration of ion mobility spectrometry (IMS) with mass spectrometry (MS) and the ability to trap ions in IMS-MS measurements is of great importance for performing reactions, accumulating ions, and increasing analytical measurement sensitivity. The development of Structures for Lossless Ion Manipulations (SLIM) offers the potential for ion manipulations in a more reliable and cost-effective manner, while opening opportunities for much more complex sequences of manipulations. Here, we demonstrate an ion separation and trapping module and a method based upon SLIM that consists of a linear mobility ion drift region, a switch/tee and a trapping region that allows the isolationmore » and accumulation of mobility-separated species. The operation and optimization of the SLIM switch/tee and trap are described and demonstrated for the enrichment of the low abundance ions. Lastly, we observed a linear increase in ion intensity with the number of trapping/accumulation events using the SLIM trap, illustrating its potential for enhancing the sensitivity of low abundance or targeted species.« less

Design and numerical characterization of a crossover EBIS

NASA Astrophysics Data System (ADS)

Geyer, Sabrina; Langbein, A.; Meusel, Oliver; Kester, Oliver

2015-01-01

For the investigation of highly charged ions, a crossover EBIS (XEBIS) was developed at the University of Frankfurt. In contrast to conventional EBIS/T devices the compression of the electron beam is achieved by electrostatic focusing to a crossover point in the interaction region. This concept allows a compact and simple design. Simulations performed with EGUN show a perveance of 2.1×10-7 A/V3/2 for the realized gun system. In the interaction region the electron beam has a density of around 10 A/cm2 and a minimum radius of 0.15 mm. The XEBIS has a total length of 112 mm with a trap length of 26 mm. It is designed for electron beam energies of up to 6 keV/q. The storage capacity of the trap region is in the order of 1×108 charges. Charge state breeding studies with CBSIM indicate for the noble gases as maximal achievable charge state Ar16+, Kr30+ and Xe35+. Thus ion beam currents of around 2.04 nA assuming 50 Hz repetition rate can be expected. The emittance of the extracted beam is approximated to 8 mm mrad. After completion of the construction phase, the XEBIS will be installed for first performance investigations at a dedicated test bench, equipped with a fast Faraday Cup (FC), a retarding field spectrometer, a luminescence screen and optical diagnostics. Subsequently the XEBIS will serve as source for highly charged ions at different experimental setups.

Surface-electrode point Paul trap

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Tony Hyun; Herskind, Peter F.; Chuang, Isaac L.

2010-10-15

We present a model as well as experimental results for a surface electrode radiofrequency Paul trap that has a circular electrode geometry well suited for trapping single ions and two-dimensional planar ion crystals. The trap design is compatible with microfabrication and offers a simple method by which the height of the trapped ions above the surface may be changed in situ. We demonstrate trapping of single {sup 88}Sr{sup +} ions over an ion height range of 200-1000 {mu}m for several hours under Doppler laser cooling and use these to characterize the trap, finding good agreement with our model.

Arbitrary amplitude electrostatic wave propagation in a magnetized dense plasma containing helium ions and degenerate electrons

NASA Astrophysics Data System (ADS)

Mahmood, S.; Sadiq, Safeer; Haque, Q.; Ali, Munazza Z.

2016-06-01

The obliquely propagating arbitrary amplitude electrostatic wave is studied in a dense magnetized plasma having singly and doubly charged helium ions with nonrelativistic and ultrarelativistic degenerate electrons pressures. The Fermi temperature for ultrarelativistic degenerate electrons described by N. M. Vernet [(Cambridge University Press, Cambridge, 2007), p. 57] is used to define ion acoustic speed in ultra-dense plasmas. The pseudo-potential approach is used to solve the fully nonlinear set of dynamic equations for obliquely propagating electrostatic waves in a dense magnetized plasma containing helium ions. The upper and lower Mach number ranges for the existence of electrostatic solitons are found which depends on the obliqueness of the wave propagation with respect to applied magnetic field and charge number of the helium ions. It is found that only compressive (hump) soliton structures are formed in all the cases and only subsonic solitons are formed for a singly charged helium ions plasma case with nonrelativistic degenerate electrons. Both subsonic and supersonic soliton hump structures are formed for doubly charged helium ions with nonrelativistic degenerate electrons and ultrarelativistic degenerate electrons plasma case containing singly as well as doubly charged helium ions. The effect of propagation direction on the soliton amplitude and width of the electrostatic waves is also presented. The numerical plots are also shown for illustration using dense plasma parameters of a compact star (white dwarf) from literature.

Magnetic and electrostatic confinement of plasma with tuning of electrostatic field

DOEpatents

Rostoker, Norman [Irvine, CA; Binderbauer, Michl [Irvine, CA; Qerushi, Artan [Irvine, CA; Tahsiri, Hooshang [Irvine, CA

2008-10-21

A system and method for containing plasma and forming a Field Reversed Configuration (FRC) magnetic topology are described in which plasma ions are contained magnetically in stable, non-adiabatic orbits in the FRC. Further, the electrons are contained electrostatically in a deep energy well, created by tuning an externally applied magnetic field. The simultaneous electrostatic confinement of electrons and magnetic confinement of ions avoids anomalous transport and facilitates classical containment of both electrons and ions. In this configuration, ions and electrons may have adequate density and temperature so that upon collisions they are fused together by nuclear force, thus releasing fusion energy. Moreover, the fusion fuel plasmas that can be used with the present confinement system and method are not limited to neutronic fuels only, but also advantageously include advanced fuels.

Magnetic and electrostatic confinement of plasma with tuning of electrostatic field

DOEpatents

Rostoker, Norman; Binderbauer, Michl; Qerushi, Artan; Tahsiri, Hooshang

2006-10-10

A system and method for containing plasma and forming a Field Reversed Configuration (FRC) magnetic topology are described in which plasma ions are contained magnetically in stable, non-adiabatic orbits in the FRC. Further, the electrons are contained electrostatically in a deep energy well, created by tuning an externally applied magnetic field. The simultaneous electrostatic confinement of electrons and magnetic confinement of ions avoids anomalous transport and facilitates classical containment of both electrons and ions. In this configuration, ions and electrons may have adequate density and temperature so that upon collisions they are fused together by nuclear force, thus releasing fusion energy. Moreover, the fusion fuel plasmas that can be used with the present confinement system and method are not limited to neutronic fuels only, but also advantageously include advanced fuels.

Magnetic and electrostatic confinement of plasma with tuning of electrostatic field

DOEpatents

Rostoker, Norman; Binderbauer, Michl; Qerushi, Artan; Tahsiri, Hooshang

2006-03-21

A system and method for containing plasma and forming a Field Reversed Configuration (FRC) magnetic topology are described in which plasma ions are contained magnetically in stable, non-adiabatic orbits in the FRC. Further, the electrons are contained electrostatically in a deep energy well, created by tuning an externally applied magnetic field. The simultaneous electrostatic confinement of electrons and magnetic confinement of ions avoids anomalous transport and facilitates classical containment of both electrons and ions. In this configuration, ions and electrons may have adequate density and temperature so that upon collisions they are fused together by nuclear force, thus releasing fusion energy. Moreover, the fusion fuel plasmas that can be used with the present confinement system and method are not limited to neutronic fuels only, but also advantageously include advanced fuels.

Electrostatic shocks and solitons in pair-ion plasmas in a two-dimensional geometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Masood, W.; Mahmood, S.; Imtiaz, N.

2009-12-15

Nonlinear electrostatic waves are studied in unmagnetized, dissipative pair-ion plasmas in the presence of weak transverse perturbations. The dissipation in the system is taken into account by incorporating the kinematic viscosity of both positive and negative ions in plasmas. The Kadomtsev-Petviashvili-Burger equation is derived using the small amplitude expansion method. The Kadomtsev-Petviashvili equation for pair-ion plasmas is also presented by ignoring the dissipative effects. Both compressive and rarefactive shocks and solitary waves are found to exist in pair-ion plasmas. The dependence of compression and rarefaction on the temperature ratios between the ion species is numerically shown. The present study maymore » have relevance to the understanding of the formation of electrostatic shocks and solitons in laboratory produced pair-ion plasmas.« less

Mass spectrometer and methods of increasing dispersion between ion beams

DOEpatents

Appelhans, Anthony D.; Olson, John E.; Delmore, James E.

2006-01-10

A mass spectrometer includes a magnetic sector configured to separate a plurality of ion beams, and an electrostatic sector configured to receive the plurality of ion beams from the magnetic sector and increase separation between the ion beams, the electrostatic sector being used as a dispersive element following magnetic separation of the plurality of ion beams. Other apparatus and methods are provided.

The formation and dissipation of electrostatic shock waves: the role of ion–ion acoustic instabilities

NASA Astrophysics Data System (ADS)

Zhang, Wen-shuai; Cai, Hong-bo; Zhu, Shao-ping

2018-05-01

The role of ion–ion acoustic instabilities in the formation and dissipation of collisionless electrostatic shock waves driven by counter-streaming supersonic plasma flows has been investigated via two-dimensional particle-in-cell simulations. The nonlinear evolution of unstable waves and ion velocity distributions has been analyzed in detail. It is found that for electrostatic shocks driven by moderate-velocity flows, longitudinal and oblique ion–ion acoustic instabilities can be excited in the downstream and upstream regions, which lead to thermalization of the transmitted and reflected ions, respectively. For high-velocity flows, oblique ion–ion acoustic instabilities can develop in the overlap layer during the shock formation process and impede the shock formation.

Method for increasing the dynamic range of mass spectrometers

DOEpatents

Belov, Mikhail; Smith, Richard D.; Udseth, Harold R.

2004-09-07

A method for enhancing the dynamic range of a mass spectrometer by first passing a sample of ions through the mass spectrometer having a quadrupole ion filter, whereupon the intensities of the mass spectrum of the sample are measured. From the mass spectrum, ions within this sample are then identified for subsequent ejection. As further sampling introduces more ions into the mass spectrometer, the appropriate rf voltages are applied to a quadrupole ion filter, thereby selectively ejecting the undesired ions previously identified. In this manner, the desired ions may be collected for longer periods of time in an ion trap, thus allowing better collection and subsequent analysis of the desired ions. The ion trap used for accumulation may be the same ion trap used for mass analysis, in which case the mass analysis is performed directly, or it may be an intermediate trap. In the case where collection is an intermediate trap, the desired ions are accumulated in the intermediate trap, and then transferred to a separate mass analyzer. The present invention finds particular utility where the mass analysis is performed in an ion trap mass spectrometer or a Fourier transform ion cyclotron resonance mass spectrometer.

Compact RF ion source for industrial electrostatic ion accelerator

NASA Astrophysics Data System (ADS)

Kwon, Hyeok-Jung; Park, Sae-Hoon; Kim, Dae-Il; Cho, Yong-Sub

2016-02-01

Korea Multi-purpose Accelerator Complex is developing a single-ended electrostatic ion accelerator to irradiate gaseous ions, such as hydrogen and nitrogen, on materials for industrial applications. ELV type high voltage power supply has been selected. Because of the limited space, electrical power, and robust operation, a 200 MHz RF ion source has been developed. In this paper, the accelerator system, test stand of the ion source, and its test results are described.

Compact RF ion source for industrial electrostatic ion accelerator.

PubMed

Kwon, Hyeok-Jung; Park, Sae-Hoon; Kim, Dae-Il; Cho, Yong-Sub

2016-02-01

Korea Multi-purpose Accelerator Complex is developing a single-ended electrostatic ion accelerator to irradiate gaseous ions, such as hydrogen and nitrogen, on materials for industrial applications. ELV type high voltage power supply has been selected. Because of the limited space, electrical power, and robust operation, a 200 MHz RF ion source has been developed. In this paper, the accelerator system, test stand of the ion source, and its test results are described.

Electrostatic wave modulation in collisional pair-ion plasmas

NASA Astrophysics Data System (ADS)

Sikdar, Arnab; Adak, Ashish; Ghosh, Samiran; Khan, Manoranjan

2018-05-01

The effects of ion-neutral collision on the electrostatic wave packets in the absence of the magnetic field in a pair-ion plasma have been investigated. Considering a two-fluid plasma model with the help of the standard perturbation technique, two distinct electrostatic modes have been observed, namely, a low-frequency ion acoustic mode and a high-frequency ion plasma mode. The dynamics of the modulated wave is governed by a damped nonlinear Schrödinger equation. Damping of the soliton occurs due to the ion-neutral collision. The analytical and numerical investigation reveals that the ion acoustic mode is both stable and unstable, which propagates in the form of dark solitons and bright solitons, respectively, whereas the ion plasma mode is unstable, propagating in the form of a bright soliton. Results are discussed in the context of the fullerene pair-ion plasma experiments.

Measurement of the orientation of buffer-gas-cooled, electrostatically-guided ammonia molecules

NASA Astrophysics Data System (ADS)

Steer, Edward W.; Petralia, Lorenzo S.; Western, Colin M.; Heazlewood, Brianna R.; Softley, Timothy P.

2017-02-01

The extent to which the spatial orientation of internally and translationally cold ammonia molecules can be controlled as molecules pass out of a quadrupole guide and through different electric field regions is examined. Ammonia molecules are collisionally cooled in a buffer gas cell, and are subsequently guided by a three-bend electrostatic quadrupole into a detection chamber. The orientation of ammonia molecules is probed using (2 + 1) resonance-enhanced multiphoton ionisation (REMPI), with the laser polarisation axis aligned both parallel and perpendicular to the time-of-flight axis. Even with the presence of a near-zero field region, the ammonia REMPI spectra indicate some retention of orientation. Monte Carlo simulations propagating the time-dependent Schrödinger equation in a full basis set including the hyperfine interaction enable the orientation of ammonia molecules to be calculated - with respect to both the local field direction and a space-fixed axis - as the molecules pass through different electric field regions. The simulations indicate that the orientation of ∼95% of ammonia molecules in JK =11 could be achieved with the application of a small bias voltage (17 V) to the mesh separating the quadrupole and detection regions. Following the recent combination of the buffer gas cell and quadrupole guide apparatus with a linear Paul ion trap, this result could enable one to examine the influence of molecular orientation on ion-molecule reaction dynamics and kinetics.

Microfabricated cylindrical ion trap

DOEpatents

Blain, Matthew G.

2005-03-22

A microscale cylindrical ion trap, having an inner radius of order one micron, can be fabricated using surface micromachining techniques and materials known to the integrated circuits manufacturing and microelectromechanical systems industries. Micromachining methods enable batch fabrication, reduced manufacturing costs, dimensional and positional precision, and monolithic integration of massive arrays of ion traps with microscale ion generation and detection devices. Massive arraying enables the microscale cylindrical ion trap to retain the resolution, sensitivity, and mass range advantages necessary for high chemical selectivity. The microscale CIT has a reduced ion mean free path, allowing operation at higher pressures with less expensive and less bulky vacuum pumping system, and with lower battery power than conventional- and miniature-sized ion traps. The reduced electrode voltage enables integration of the microscale cylindrical ion trap with on-chip integrated circuit-based rf operation and detection electronics (i.e., cell phone electronics). Therefore, the full performance advantages of microscale cylindrical ion traps can be realized in truly field portable, handheld microanalysis systems.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kleinert, J.; Haimberger, C.; Zabawa, P. J.

We describe the realization of a dc electric-field trap for ultracold polar molecules, the thin-wire electrostatic trap (TWIST). The thin wires that form the electrodes of the TWIST allow us to superimpose the trap onto a magneto-optical trap (MOT). In our experiment, ultracold polar NaCs molecules in their electronic ground state are created in the MOT via photoassociation, achieving a continuous accumulation in the TWIST of molecules in low-field seeking states. Initial measurements show that the TWIST trap lifetime is limited only by the background pressure in the chamber.

Ball-grid array architecture for microfabricated ion traps

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guise, Nicholas D., E-mail: nicholas.guise@gtri.gatech.edu; Fallek, Spencer D.; Stevens, Kelly E.

2015-05-07

State-of-the-art microfabricated ion traps for quantum information research are approaching nearly one hundred control electrodes. We report here on the development and testing of a new architecture for microfabricated ion traps, built around ball-grid array (BGA) connections, that is suitable for increasingly complex trap designs. In the BGA trap, through-substrate vias bring electrical signals from the back side of the trap die to the surface trap structure on the top side. Gold-ball bump bonds connect the back side of the trap die to an interposer for signal routing from the carrier. Trench capacitors fabricated into the trap die replace area-intensivemore » surface or edge capacitors. Wirebonds in the BGA architecture are moved to the interposer. These last two features allow the trap die to be reduced to only the area required to produce trapping fields. The smaller trap dimensions allow tight focusing of an addressing laser beam for fast single-qubit rotations. Performance of the BGA trap as characterized with {sup 40}Ca{sup +} ions is comparable to previous surface-electrode traps in terms of ion heating rate, mode frequency stability, and storage lifetime. We demonstrate two-qubit entanglement operations with {sup 171}Yb{sup +} ions in a second BGA trap.« less

Electron Trapping and Charge Transport by Large Amplitude Whistlers

NASA Technical Reports Server (NTRS)

Kellogg, P. J.; Cattell, C. A.; Goetz, K.; Monson, S. J.; Wilson, L. B., III

2010-01-01

Trapping of electrons by magnetospheric whistlers is investigated using data from the Waves experiment on Wind and the S/WAVES experiment on STEREO. Waveforms often show a characteristic distortion which is shown to be due to electrons trapped in the potential of the electrostatic part of oblique whistlers. The density of trapped electrons is significant, comparable to that of the unperturbed whistler. Transport of these trapped electrons to new regions can generate potentials of several kilovolts, Trapping and the associated potentials may play an important role in the acceleration of Earth's radiation belt electrons.

Impurities, temperature, and density in a miniature electrostatic plasma and current source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Den Hartog, D.J.; Craig, D.J.; Fiksel, G.

1996-10-01

We have spectroscopically investigated the Sterling Scientific miniature electrostatic plasma source-a plasma gun. This gun is a clean source of high density (10{sup 19} - 10{sup 20} m{sup -3}), low temperature (5 - 15 eV) plasma. A key result of our investigation is that molybdenum from the gun electrodes is largely trapped in the internal gun discharge; only a small amount escapes in the plasma flowing out of the gun. In addition, the gun plasma parameters actually improve (even lower impurity contamination and higher ion temperature) when up to 1 kA of electron current is extracted from the gun viamore » the application of an external bias. This improvement occurs because the internal gun anode no longer acts as the current return for the internal gun discharge. The gun plasma is a virtual plasma electrode capable of sourcing an electron emission current density of 1 kA/cm{sup 2}. The high emission current, small size (3 - 4 cm diameter), and low impurity generation make this gun attractive for a variety of fusion and plasma technology applications.« less

A molecular dynamics simulation study on trapping ions in a nanoscale Paul trap

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhao, Xiongce; Krstic, Predrag S

2008-01-01

We found by molecular dynamics simulations that a low energy ion can be trapped effectively in a nanoscale Paul trap in both vacuum and in aqueous environment when appropriate AC/DC electric fields are applied to the system. Using the negatively charged chlorine ion as an example, we show that the trapped ion oscillates around the center of the nanotrap with the amplitude dependent on the parameters of the system and applied voltage. Successful trapping of the ion within nanoseconds requires electric bias of GHz frequency, in the range of hundreds of mV. The oscillations are damped in the aqueous environment,more » but polarization of the water molecules requires application of the higher voltage biases to reach the improved stability of the trapping. Application of a supplemental DC driving field along the trap axis can effectively drive the ion off the trap center and out of the trap, opening a possibility of studying DNA and other biological molecules using embedded probes while achieving a full control of their translocation and localization in the trap.« less

Solar wind interaction with dusty plasmas produces instabilities and solitary structures

NASA Astrophysics Data System (ADS)

Saleem, H.; Ali, S.

2017-12-01

It is pointed out that the solar wind interaction with dusty magnetospheres of the planets can give rise to purely growing instabilities as well as nonlinear electric field structures. Linear dispersion relation of the low frequency electrostatic ion-acoustic wave (IAW) is modified in the presence of stationary dust and its frequency becomes larger than its frequency in usual electron ion plasma even if ion temperature is equal to the electron temperature. This dust-ion-acoustic wave (DIAW) either becomes a purely growing electrostatic instability or turns out to be the modified dust-ion-acoustic wave (mDIAW) depending upon the magnitude of shear flow scale length and its direction. Growth rate of shear flow-driven electrostatic instability in a plasma having negatively charged stationary dust is larger than the usual D'Angelo instability of electron-ion plasma. It is shown that shear modified dust ion acoustic wave (mDIAW) produces electrostatic solitons in the nonlinear regime. The fluid theory predicts the existence of electrostatic solitons in the dusty plasmas in those regions where the inhomogeneous solar wind flow is parallel to the planetary or cometary magnetic field lines. The amplitude and width of the solitary structure depends upon dust density and magnitude of shear in the flow. This is a general theoretical model which is applied to dusty plasma of Saturn's F-ring for illustration.

Experimental Methods for Trapping Ions Using Microfabricated Surface Ion Traps

PubMed Central

Hong, Seokjun; Lee, Minjae; Kwon, Yeong-Dae; Cho, Dong-il "Dan"; Kim, Taehyun

2017-01-01

Ions trapped in a quadrupole Paul trap have been considered one of the strong physical candidates to implement quantum information processing. This is due to their long coherence time and their capability to manipulate and detect individual quantum bits (qubits). In more recent years, microfabricated surface ion traps have received more attention for large-scale integrated qubit platforms. This paper presents a microfabrication methodology for ion traps using micro-electro-mechanical system (MEMS) technology, including the fabrication method for a 14 µm-thick dielectric layer and metal overhang structures atop the dielectric layer. In addition, an experimental procedure for trapping ytterbium (Yb) ions of isotope 174 (174Yb+) using 369.5 nm, 399 nm, and 935 nm diode lasers is described. These methodologies and procedures involve many scientific and engineering disciplines, and this paper first presents the detailed experimental procedures. The methods discussed in this paper can easily be extended to the trapping of Yb ions of isotope 171 (171Yb+) and to the manipulation of qubits. PMID:28872137

Ionic strength independence of charge distributions in solvation of biomolecules

NASA Astrophysics Data System (ADS)

Virtanen, J. J.; Sosnick, T. R.; Freed, K. F.

2014-12-01

Electrostatic forces enormously impact the structure, interactions, and function of biomolecules. We perform all-atom molecular dynamics simulations for 5 proteins and 5 RNAs to determine the dependence on ionic strength of the ion and water charge distributions surrounding the biomolecules, as well as the contributions of ions to the electrostatic free energy of interaction between the biomolecule and the surrounding salt solution (for a total of 40 different biomolecule/solvent combinations). Although water provides the dominant contribution to the charge density distribution and to the electrostatic potential even in 1M NaCl solutions, the contributions of water molecules and of ions to the total electrostatic interaction free energy with the solvated biomolecule are comparable. The electrostatic biomolecule/solvent interaction energies and the total charge distribution exhibit a remarkable insensitivity to salt concentrations over a huge range of salt concentrations (20 mM to 1M NaCl). The electrostatic potentials near the biomolecule's surface obtained from the MD simulations differ markedly, as expected, from the potentials predicted by continuum dielectric models, even though the total electrostatic interaction free energies are within 11% of each other.

Collisional Cooling of Light Ions by Cotrapped Heavy Atoms.

PubMed

Dutta, Sourav; Sawant, Rahul; Rangwala, S A

2017-03-17

We experimentally demonstrate cooling of trapped ions by collisions with cotrapped, higher-mass neutral atoms. It is shown that the lighter ^{39}K^{+} ions, created by ionizing ^{39}K atoms in a magneto-optical trap (MOT), when trapped in an ion trap and subsequently allowed to cool by collisions with ultracold, heavier ^{85}Rb atoms in a MOT, exhibit a longer trap lifetime than without the localized ^{85}Rb MOT atoms. A similar cooling of trapped ^{85}Rb^{+} ions by ultracold ^{133}Cs atoms in a MOT is also demonstrated in a different experimental configuration to validate this mechanism of ion cooling by localized and centered ultracold neutral atoms. Our results suggest that the cooling of ions by localized cold atoms holds for any mass ratio, thereby enabling studies on a wider class of atom-ion systems irrespective of their masses.

Improved Linear-Ion-Trap Frequency Standard

NASA Technical Reports Server (NTRS)

Prestage, John D.

1995-01-01

Improved design concept for linear-ion-trap (LIT) frequency-standard apparatus proposed. Apparatus contains lengthened linear ion trap, and ions processed alternately in two regions: ions prepared in upper region of trap, then transported to lower region for exposure to microwave radiation, then returned to upper region for optical interrogation. Improved design intended to increase long-term frequency stability of apparatus while reducing size, mass, and cost.

A multiscale model for charge inversion in electric double layers

NASA Astrophysics Data System (ADS)

Mashayak, S. Y.; Aluru, N. R.

2018-06-01

Charge inversion is a widely observed phenomenon. It is a result of the rich statistical mechanics of the molecular interactions between ions, solvent, and charged surfaces near electric double layers (EDLs). Electrostatic correlations between ions and hydration interactions between ions and water molecules play a dominant role in determining the distribution of ions in EDLs. Due to highly polar nature of water, near a surface, an inhomogeneous and anisotropic arrangement of water molecules gives rise to pronounced variations in the electrostatic and hydration energies of ions. Classical continuum theories fail to accurately describe electrostatic correlations and molecular effects of water in EDLs. In this work, we present an empirical potential based quasi-continuum theory (EQT) to accurately predict the molecular-level properties of aqueous electrolytes. In EQT, we employ rigorous statistical mechanics tools to incorporate interatomic interactions, long-range electrostatics, correlations, and orientation polarization effects at a continuum-level. Explicit consideration of atomic interactions of water molecules is both theoretically and numerically challenging. We develop a systematic coarse-graining approach to coarse-grain interactions of water molecules and electrolyte ions from a high-resolution atomistic scale to the continuum scale. To demonstrate the ability of EQT to incorporate the water orientation polarization, ion hydration, and electrostatic correlations effects, we simulate confined KCl aqueous electrolyte and show that EQT can accurately predict the distribution of ions in a thin EDL and also predict the complex phenomenon of charge inversion.

Arbitrary amplitude electrostatic wave propagation in a magnetized dense plasma containing helium ions and degenerate electrons

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mahmood, S., E-mail: shahzadm100@gmail.com; Sadiq, Safeer; Haque, Q.

2016-06-15

The obliquely propagating arbitrary amplitude electrostatic wave is studied in a dense magnetized plasma having singly and doubly charged helium ions with nonrelativistic and ultrarelativistic degenerate electrons pressures. The Fermi temperature for ultrarelativistic degenerate electrons described by N. M. Vernet [(Cambridge University Press, Cambridge, 2007), p. 57] is used to define ion acoustic speed in ultra-dense plasmas. The pseudo-potential approach is used to solve the fully nonlinear set of dynamic equations for obliquely propagating electrostatic waves in a dense magnetized plasma containing helium ions. The upper and lower Mach number ranges for the existence of electrostatic solitons are found whichmore » depends on the obliqueness of the wave propagation with respect to applied magnetic field and charge number of the helium ions. It is found that only compressive (hump) soliton structures are formed in all the cases and only subsonic solitons are formed for a singly charged helium ions plasma case with nonrelativistic degenerate electrons. Both subsonic and supersonic soliton hump structures are formed for doubly charged helium ions with nonrelativistic degenerate electrons and ultrarelativistic degenerate electrons plasma case containing singly as well as doubly charged helium ions. The effect of propagation direction on the soliton amplitude and width of the electrostatic waves is also presented. The numerical plots are also shown for illustration using dense plasma parameters of a compact star (white dwarf) from literature.« less

A second-order theory for transverse ion heating and momentum coupling due to electrostatic ion cyclotron waves

NASA Technical Reports Server (NTRS)

Miller, Ronald H.; Winske, Dan; Gary, S. P.

1992-01-01

A second-order theory for electrostatic instabilities driven by counterstreaming ion beams is developed which describes momentum coupling and heating of the plasma via wave-particle interactions. Exchange rates between the waves and particles are derived, which are suitable for the fluid equations simulating microscopic effects on macroscopic scales. Using a fully kinetic simulation, the electrostatic ion cyclotron instability due to counterstreaming H(+) beams has been simulated. A power spectrum from the kinetic simulation is used to evaluate second-order exchange rates. The calculated heating and momentum loss from second-order theory is compared to the numerical simulation.

Use of phenyl/tetrazolyl-functionalized magnetic microspheres and stable isotope labeled internal standards for significant reduction of matrix effect in determination of nine fluoroquinolones by liquid chromatography-quadrupole linear ion trap mass spectrometry.

PubMed

Xu, Fei; Liu, Feng; Wang, Chaozhan; Wei, Yinmao

2018-02-01

In this study, the strategy of unique adsorbent combined with isotope labeled internal standards was used to significantly reduce the matrix effect for the enrichment and analysis of nine fluoroquinolones in a complex sample by liquid chromatography coupled to quadrupole linear ion trap mass spectrometry (LC-QqQ LIT -MS/MS). The adsorbent was prepared conveniently by functionalizing Fe 3 O 4 @SiO 2 microspheres with phenyl and tetrazolyl groups, which could adsorb fluoroquinolones selectively via hydrophobic, electrostatic, and π-π interactions. The established magnetic solid-phase extraction (MSPE) method as well as using stable isotope labeled internal standards in the next MS/MS detection was able to reduce the matrix effect significantly. In the process of LC-QqQ LIT -MS/MS analysis, the precursor and product ions of the analytes were monitored quantitatively and qualitatively on a QTrap system equipped simultaneously with the multiple reaction monitoring (MRM) and enhanced product ion (EPI) scan. Subsequently, the enrichment method combined with LC-QqQ LIT -MS/MS demonstrated good analytical features in terms of linearity (7.5-100.0 ng mL -1 , r > 0.9960), satisfactory recoveries (88.6%-118.3%) with RSDs < 12.0%, LODs = 0.5 μg kg -1 and LOQs = 1.5 μg kg -1 for all tested analytes. Finally, the developed MSPE-LC-QqQ LIT -MS/MS method had been successfully applied to real pork samples for food-safety risk monitoring in Ningxia Province, China. Graphical abstract Mechanism of reducing matrix effect through the as-prepared adsorbent.

Characterization of the internal ion environment of biofilms based on charge density and shape of ion.

PubMed

Kurniawan, Andi; Tsuchiya, Yuki; Eda, Shima; Morisaki, Hisao

2015-12-01

Biofilm polymers contain both electrically positively and negatively charged sites. These charged sites enable the biofilm to trap and retain ions leading to an important role of biofilm such as nutrient recycling and pollutant purification. Much work has focused on the ion-exchange capacity of biofilms, and they are known to adsorb ions through an exchange mechanism between the ions in solution and the ions adsorbed to the charged sites on the biofilm polymer. However, recent studies suggest that the adsorption/desorption behavior of ions in a biofilm cannot be explained solely by this ion exchange mechanism. To examine the possibility that a substantial amount of ions are held in the interstitial region of the biofilm polymer by an electrostatic interaction, intact biofilms formed in a natural environment were immersed in distilled water and ion desorption was investigated. All of the detected ion species were released from the biofilms over a short period of time, and very few ions were subsequently released over more time, indicating that the interstitial region of biofilm polymers is another ion reserve. The extent of ion retention in the interstitial region of biofilms for each ion can be determined largely by charge density, |Z|/r, where |Z| is the ion valence as absolute value and r is the ion radius. The higher |Z|/r value an ion has, the stronger it is retained in the interstitial region of biofilms. Ion shape is also a key determinant of ion retention. Spherical and non-spherical ions have different correlations between the condensation ratio and |Z|/r. The generality of these findings were assured by various biofilm samples. Thus, the internal regions of biofilms exchange ions dynamically with the outside environment. Copyright © 2015 Elsevier B.V. All rights reserved.

Optical Trapping of Ion Coulomb Crystals

NASA Astrophysics Data System (ADS)

Schmidt, Julian; Lambrecht, Alexander; Weckesser, Pascal; Debatin, Markus; Karpa, Leon; Schaetz, Tobias

2018-04-01

The electronic and motional degrees of freedom of trapped ions can be controlled and coherently coupled on the level of individual quanta. Assembling complex quantum systems ion by ion while keeping this unique level of control remains a challenging task. For many applications, linear chains of ions in conventional traps are ideally suited to address this problem. However, driven motion due to the magnetic or radio-frequency electric trapping fields sometimes limits the performance in one dimension and severely affects the extension to higher-dimensional systems. Here, we report on the trapping of multiple barium ions in a single-beam optical dipole trap without radio-frequency or additional magnetic fields. We study the persistence of order in ensembles of up to six ions within the optical trap, measure their temperature, and conclude that the ions form a linear chain, commonly called a one-dimensional Coulomb crystal. As a proof-of-concept demonstration, we access the collective motion and perform spectrometry of the normal modes in the optical trap. Our system provides a platform that is free of driven motion and combines advantages of optical trapping, such as state-dependent confinement and nanoscale potentials, with the desirable properties of crystals of trapped ions, such as long-range interactions featuring collective motion. Starting with small numbers of ions, it has been proposed that these properties would allow the experimental study of many-body physics and the onset of structural quantum phase transitions between one- and two-dimensional crystals.

The electrostatic interaction between interfacial colloidal particles

NASA Astrophysics Data System (ADS)

Hurd, A. J.

1985-11-01

The electrostatic interaction between charged, colloidal particles trapped at an air-water interface is considered using linearised Poisson-Boltzmann results for point particles. In addition to the expected screened-Coulomb contribution, which decays exponentially, an algebraic dipole-dipole interaction occurs that may account for long-range interactions in interfacial colloidal systems.

A Scalable Microfabricated Ion Trap for Quantum Information Processing

NASA Astrophysics Data System (ADS)

Maunz, Peter; Haltli, Raymond; Hollowell, Andrew; Lobser, Daniel; Mizrahi, Jonathan; Rembetski, John; Resnick, Paul; Sterk, Jonathan D.; Stick, Daniel L.; Blain, Matthew G.

2016-05-01

Trapped Ion Quantum Information Processing (QIP) relies on complex microfabricated trap structures to enable scaling of the number of quantum bits. Building on previous demonstrations of surface-electrode ion traps, we have designed and characterized the Sandia high-optical-access (HOA-2) microfabricated ion trap. This trap features high optical access, high trap frequencies, low heating rates, and negligible charging of dielectric trap components. We have observed trap lifetimes of more than 100h, measured trap heating rates for ytterbium of less than 40quanta/s, and demonstrated shuttling of ions from a slotted to an above surface region and through a Y-junction. Furthermore, we summarize demonstrations of high-fidelity single and two-qubit gates realized in this trap. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy's National Nuclear Security Administration under Contract DE-AC04-94AL85000. This work was supported by the Intelligence Advanced Research Projects Activity (IARPA).

Long-range electrostatic screening in ionic liquids

PubMed Central

Gebbie, Matthew A.; Dobbs, Howard A.; Valtiner, Markus; Israelachvili, Jacob N.

2015-01-01

Electrolyte solutions with high concentrations of ions are prevalent in biological systems and energy storage technologies. Nevertheless, the high interaction free energy and long-range nature of electrostatic interactions makes the development of a general conceptual picture of concentrated electrolytes a significant challenge. In this work, we study ionic liquids, single-component liquids composed solely of ions, in an attempt to provide a novel perspective on electrostatic screening in very high concentration (nonideal) electrolytes. We use temperature-dependent surface force measurements to demonstrate that the long-range, exponentially decaying diffuse double-layer forces observed across ionic liquids exhibit a pronounced temperature dependence: Increasing the temperature decreases the measured exponential (Debye) decay length, implying an increase in the thermally driven effective free-ion concentration in the bulk ionic liquids. We use our quantitative results to propose a general model of long-range electrostatic screening in ionic liquids, where thermally activated charge fluctuations, either free ions or correlated domains (quasiparticles), take on the role of ions in traditional dilute electrolyte solutions. This picture represents a crucial step toward resolving several inconsistencies surrounding electrostatic screening and charge transport in ionic liquids that have impeded progress within the interdisciplinary ionic liquids community. More broadly, our work provides a previously unidentified way of envisioning highly concentrated electrolytes, with implications for diverse areas of inquiry, ranging from designing electrochemical devices to rationalizing electrostatic interactions in biological systems. PMID:26040001

Demonstrating H- beam focusing using an elliptical einzel lens

NASA Astrophysics Data System (ADS)

Lawrie, S. R.; Faircloth, D. C.; Letchford, A. P.; Whitehead, M. O.; Wood, T.

2017-08-01

H- ion source research is being performed at the ISIS spallation neutron and muon facility on a dedicated Vessel for Extraction and Source Plasma Analyses (VESPA). The ion extraction and optics system presently being used on ISIS is centered on a combined-function sector dipole magnet. This traps cesium vapor escaping the ion source; mass-separates co-extracted electrons and stripped neutrals, and weak-focusses the highly asymmetric slit-shaped ion beam. Unfortunately the added drift length through the magnet under strong space-charge forces means up to 50% of the beam is collimated on the magnet. The VESPA has shown that the ISIS ion source actually produces 80 mA of beam current at standard settings, but because of magnet collimation only 55 mA is injected into the solenoid Low Energy Beam Transport (LEBT). A new purely electrostatic post-extraction system incorporating an einzel lens with an elliptical aperture is currently under test. This allows much greater flexibility of perveance and phase space matching for injection into the LEBT and Radio Frequency Quadrupole (RFQ). This paper discusses high voltage breakdown mitigation strategies and presents the first results of the novel elliptical transport system. So far, 70 mA of beam has been transported through the new system with a normalized transverse RMS emittance of 0.2 π mm mrad.

Extending the Dynamic Range of the Ion Trap by Differential Mobility Filtration

PubMed Central

Hall, Adam B.; Coy, Stephen L.; Kafle, Amol; Glick, James; Nazarov, Erkinjon

2013-01-01

A miniature, planar, differential ion mobility spectrometer (DMS) was interfaced to an LCQ classic ion trap to conduct selective ion filtration prior to mass analysis in order to extend the dynamic range of the trap. Space charge effects are known to limit the functional ion storage capacity of ion trap mass analyzers and this, in turn, can affect the quality of the mass spectral data generated. This problem is further exacerbated in the analysis of mixtures where the indiscriminate introduction of matrix ions results in premature trap saturation with non-targeted species, thereby reducing the number of parent ions that may be used to conduct MS/MS experiments for quantitation or other diagnostic studies. We show that conducting differential mobility-based separations prior to mass analysis allows the isolation of targeted analytes from electrosprayed mixtures preventing the indiscriminate introduction of matrix ions and premature trap saturation with analytically unrelated species. Coupling these two analytical techniques is shown to enhance the detection of a targeted drug metabolite from a biological matrix. In its capacity as a selective ion filter, the DMS can improve the analytical performance of analyzers such as quadrupole (3-D or linear) and ion cyclotron resonance (FT-ICR) ion traps that depend on ion accumulation. PMID:23797861

Particle-in-cell/accelerator code for space-charge dominated beam simulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

2012-05-08

Warp is a multidimensional discrete-particle beam simulation program designed to be applicable where the beam space-charge is non-negligible or dominant. It is being developed in a collaboration among LLNL, LBNL and the University of Maryland. It was originally designed and optimized for heave ion fusion accelerator physics studies, but has received use in a broader range of applications, including for example laser wakefield accelerators, e-cloud studies in high enery accelerators, particle traps and other areas. At present it incorporates 3-D, axisymmetric (r,z) planar (x-z) and transverse slice (x,y) descriptions, with both electrostatic and electro-magnetic fields, and a beam envelope model.more » The code is guilt atop the Python interpreter language.« less

Space Environment Effects on Materials : An Overview

NASA Technical Reports Server (NTRS)

Garrett, Henry B.

2006-01-01

A general overview on the space environment and its effects on materials is presented. The topics include: 1) Impact of Space Effects on Spacecraft Costs; 2) Space Environment Effects on Spacecraft by Source; 3) Primary Source of Space Effects: The Sun; 4) The Earth's Environment; 5) Trapped Radiation Belts; 6) Aurora Are Everywhere; 7) Spacecraft Interactions; 8) Atmospheric Effects; 9) Contaminant Effects on Materials; 10) Meteoroid/Debris Effects on Materials; 11) Spacecraft Surface Charging; 12) Surface Discharge Effects; 13) Internal Electrostatic Discharge--Satellite Killer; 14) Plasma Interactions DS-1 Ion Engines; 15) Radiation Effects on Spacecraft Systems and Materials; 16) Total Ionizing Dose Effects Total Ionizing Dose Effects; 17) Man-Made Sources of Space Effects Man-Made Sources of Space Effects; and 18) Space Environments Versus Interactions.

Technologies for Trapped-Ion Quantum Information Systems

DTIC Science & Technology

2016-03-21

mate- rials such as graphene and indium tin oxide, integrating devices like optical fibers and mirrors, and exploring alternative ion loading and...trapping techniques. Keywords ion traps · quantum computation · quantum information · trapped ions · ion-photon interface · graphene · indium tin oxide...displays are typically made of indium tin oxide (ITO), a material that is both an elec- trical and an optical conductor. However, using ITO electrodes

Extending the applicability of an open-ring trap to perform experiments with a single laser-cooled ion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cornejo, J. M.; Colombano, M.; Doménech, J.

A special ion trap was initially built up to perform β-ν correlation experiments with radioactive ions. The trap geometry is also well suited to perform experiments with laser-cooled ions, serving for the development of a new type of Penning trap, in the framework of the project TRAPSENSOR at the University of Granada. The goal of this project is to use a single {sup 40}Ca{sup +} ion as detector for single-ion mass spectrometry. Within this project and without any modification to the initial electrode configuration, it was possible to perform Doppler cooling on {sup 40}Ca{sup +} ions, starting from large cloudsmore » and reaching single ion sensitivity. This new feature of the trap might be important also for other experiments with ions produced at radioactive ion beam facilities. In this publication, the trap and the laser system will be described, together with their performance with respect to laser cooling applied to large ion clouds down to a single ion.« less

Loading of mass spectrometry ion trap with Th ions by laser ablation for nuclear frequency standard application.

PubMed

Borisyuk, Petr V; Derevyashkin, Sergey P; Khabarova, Ksenia Y; Kolachevsky, Nikolay N; Lebedinsky, Yury Y; Poteshin, Sergey S; Sysoev, Alexey A; Tkalya, Evgeny V; Tregubov, Dmitry O; Troyan, Viktor I; Vasiliev, Oleg S; Yakovlev, Valery P; Yudin, Valery I

2017-08-01

We describe an original multisectional quadrupole ion trap aimed to realize nuclear frequency standard based on the unique isomer transition in thorium nucleus. It is shown that the system effectively operates on Th + , Th 2+ and Th 3+ ions produced by laser ablation of metallic thorium-232 target. Laser intensity used for ablation is about 6 GW/cm 2 . Via applying a bias potential to every control voltage including the RF one, we are able not only to manipulate ions within the energy range as wide as 1-500 eV but to specially adjust trap potentials in order to work mainly with ions that belong to energy distribution maximum and therefore to effectively enhance the number of trapped ions. Measurement of energy distributions of 232 Th + , 232 Th 2+ , 232 Th 3+ ions obtained by laser ablation allows us to define optimal potential values for trapping process. Observed number of ions inside trap in dependence on trapping time is found to obey an unusually slow - logarithmic decay law that needs more careful study.

High-fidelity operations in microfabricated surface ion traps

NASA Astrophysics Data System (ADS)

Maunz, Peter

2017-04-01

Trapped ion systems can be used to implement quantum computation as well as quantum simulation. To scale these systems to the number of qubits required to solve interesting problems in quantum chemistry or solid state physics, the use of large multi-zone ion traps has been proposed. Microfabrication enables the realization of surface electrode ion traps with complex electrode structures. While these traps may enable the scaling of trapped ion quantum information processing (QIP), microfabricated ion traps also pose several technical challenges. Here, we present Sandia's trap fabrication capabilities and characterize trap properties and shuttling operations in our most recent high optical access trap (HOA-2). To demonstrate the viability of Sandia's microfabricated ion traps for QIP we realize robust single and two-qubit gates and characterize them using gate set tomography (GST). In this way we are able to demonstrate the first single qubit gates with a diamond norm of less than 1 . 7 ×10-4 , below a rigorous fault tolerance threshold for general noise of 6 . 7 ×10-4. Furthermore, we realize Mølmer-Sørensen two qubit gates with a process fidelity of 99 . 58(6) % also characterized by GST. These results demonstrate the viability of microfabricated surface traps for state of the art quantum information processing demonstrations. This research was funded, in part, by the Office of the Director of National Intelligence (ODNI), Intelligence Advanced Research Projects Activity (IARPA).

Ion trap simulation program, ITSIM: A powerful heuristic and predictive tool in ion trap mass spectrometry

NASA Astrophysics Data System (ADS)

Bui, Huy Anh

The multi-particle simulation program, ITSIM version 4.0, takes advantage of the enhanced performance of the Windows 95 and NT operating systems in areas such as memory management, user friendliness, flexibility of graphics and speed, to investigate the motion of ions in the quadrupole ion trap. The objective of this program is to use computer simulations based on mathematical models to improve the performance of the ion trap mass spectrometer. The simulation program can provide assistance in understanding fundamental aspects of ion trap mass spectrometry, precede and help to direct the course of experiments, as well as having didactic value in elucidating and allowing visualization of ion behavior under different experimental conditions. The program uses the improved Euler method to calculate ion trajectories as numerical solutions to the Mathieu differential equation. This Windows version can simultaneously simulate the trajectories of ions with a virtually unlimited number of different mass-to-charge ratios and hence allows realistic mass spectra, ion kinetic energy distributions and other experimentally measurable properties to be simulated. The large number of simulated ions allows examination of (i) the offsetting effects of mutual ion repulsion and collisional cooling in an ion trap and (ii) the effects of higher order fields. Field inhomogeneities arising from exit holes, electrode misalignment, imperfect electrode surfaces or new trap geometries can be simulated with the program. The simulated data are used to obtain mass spectra from mass-selective instability scans as well as by Fourier transformation of image currents induced by coherently moving ion clouds. Complete instruments, from an ion source through the ion trap mass analyzer to a detector, can now be simulated. Applications of the simulation program are presented and discussed. Comparisons are made between the simulations and experimental data. Fourier transformed experiments and a novel six-electrode ion trap mass spectrometer illustrate cases in which simulations precede new experiments. Broadband non-destructive ion detection based on induced image current measurements are described in the case of a quadrupole ion trap having cylindrical geometry.

New ion trap for atomic frequency standard applications

NASA Technical Reports Server (NTRS)

Prestage, J. D.; Dick, G. J.; Maleki, L.

1989-01-01

A novel linear ion trap that permits storage of a large number of ions with reduced susceptibility to the second-order Doppler effect caused by the radio frequency (RF) confining fields has been designed and built. This new trap should store about 20 times the number of ions a conventional RF trap stores with no corresponding increase in second-order Doppler shift from the confining field. In addition, the sensitivity of this shift to trapping parameters, i.e., RF voltage, RF frequency, and trap size, is greatly reduced.

A Charge-Exchange Neutral Particle Analyzer for an Inertial Electrostatic Confinement Fusion Device

NASA Astrophysics Data System (ADS)

Becerra, Gabriel; Kulcinski, Gerald; Santarius, John; Emmert, Gilbert

2013-10-01

An electrostatic energy analyzer for outgoing charge-exchange neutral particles has been designed and constructed for application on HELIOS, an inertial electrostatic confinement (IEC) fusion device designed for advanced fuel studies. Ions are extracted from an external helicon plasma source and subsequently accelerated radially into an electrostatic potential well set up by a semi-transparent cathode grid inside the HELIOS spherical chamber. Analysis of fast neutrals produced by charge exchange between energetic ions and background gas yields information on primary ion energy spectra, as well as a quantitative measure of charge exchange as an energy loss mechanism in IEC devices. Preliminary data with helium is used to benchmark the two-charge-state helium formalism of VICTER, a numerical code on spherically convergent ion flow, as it relates to IEC operation with helium-3 fuel. Research supported by the Greatbatch Foundation.

Trapping, retention and laser cooling of Th3+ ions in a multisection linear quadrupole trap

NASA Astrophysics Data System (ADS)

Borisyuk, P. V.; Vasil'ev, O. S.; Derevyashkin, S. P.; Kolachevsky, N. N.; Lebedinskii, Yu. Yu.; Poteshin, S. S.; Sysoev, A. A.; Tkalya, E. V.; Tregubov, D. O.; Troyan, V. I.; Khabarova, K. Yu.; Yudin, V. I.; Yakovlev, V. P.

2017-06-01

A multisection linear quadrupole trap for Th3+ ions is described. Multiply charged ions are obtained by the laser ablation method. The possibility of trapping and retention of ˜103 ions is demonstrated in macroscopic time scales of ˜30 s. Specific features of cooling Th3+ ions on the electron transitions with wavelengths of 1088, 690 and 984 nm in Th3+ ion are discussed; a principal scheme of a setup for laser cooling is presented.

The impact of electrostatic correlations on Dielectrophoresis of Non-conducting Particles

NASA Astrophysics Data System (ADS)

Alidoosti, Elaheh; Zhao, Hui

2017-11-01

The dipole moment of a charged, dielectric, spherical particle under the influence of a uniform alternating electric field is computed theoretically and numerically by solving the modified continuum Poisson-Nernst-Planck (PNP) equations accounting for ion-ion electrostatic correlations that is important at concentrated electrolytes (Phys. Rev. Lett. 106, 2011). The dependence on the frequency, zeta potential, electrostatic correlation lengths, and double layer thickness is thoroughly investigated. In the limit of thin double layers, we carry out asymptotic analysis to develop simple models which are in good agreement with the modified PNP model. Our results suggest that the electrostatic correlations have a complicated impact on the dipole moment. As the electrostatic correlations length increases, the dipole moment decreases, initially, reach a minimum, and then increases since the surface conduction first decreases and then increases due to the ion-ion correlations. The modified PNP model can improve the theoretical predictions particularly at low frequencies where the simple model can't qualitatively predict the dipole moment. This work was supported, in part, by NIH R15GM116039.

Cryogenically cooled octupole ion trap for spectroscopy of biomolecular ions.

PubMed

Boyarkin, Oleg V; Kopysov, Vladimir

2014-03-01

We present here the design of a linear octupole ion trap, suitable for collisional cryogenic cooling and spectroscopy of large ions. The performance of this trap has been assessed using ultraviolet (UV) photofragmentation spectroscopy of protonated dipeptides. At the trap temperature of 6.1 K, the vibrational temperature of the ions reaches 9.1 K, although their estimated translational temperature is ~150 K. This observation suggests that, despite the significant translational heating by radio-frequency electrical field, vibrational cooling of heavy ions in the octupole is at least as efficient as in the 22-pole ion traps previously used in our laboratory. In contrast to the 22-pole traps, excellent radial confinement of ions in the octupole makes it convenient for laser spectroscopy and boosts the dissociation yield of the stored ions to 30%. Overlap of the entire ion cloud by the laser beam in the octupole also allows for efficient UV depletion spectroscopy of ion-He clusters. The measured electronic spectra of the dipeptides and the clusters differ drastically, complicating a use of UV tagging spectroscopy for structural determination of large species.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Tsung-Chi; Ibrahim, Yehia M.; Webb, Ian K.

The integration of ion mobility spectrometry (IMS) with mass spectrometry (MS) and the ability to trap ions in IMS-MS measurements is of great importance for performing reactions, accumulating ions, and increasing analytical measurement sensitivity. The development of Structures for Lossless Ion Manipulations (SLIM) offers the potential for ion manipulations in a more reliable and cost-effective manner, while opening opportunities for much more complex sequences of manipulations. Here, we demonstrate an ion separation and trapping module and a method based upon SLIM that consists of a linear mobility ion drift region, a switch/tee and a trapping region that allows the isolationmore » and accumulation of mobility-separated species. The operation and optimization of the SLIM switch/tee and trap are described and demonstrated for the enrichment of the low abundance ions. Lastly, we observed a linear increase in ion intensity with the number of trapping/accumulation events using the SLIM trap, illustrating its potential for enhancing the sensitivity of low abundance or targeted species.« less

Self-consistent electrostatic potential due to trapped plasma in the magnetosphere

NASA Technical Reports Server (NTRS)

Miller, Ronald H.; Khazanov, George V.

1993-01-01

A steady state solution for the self-consistent electrostatic potential due to a plasma confined in a magnetic flux tube is considered. A steady state distribution function is constructed for the trapped particles from the constants of the motion, in the absence of waves and collisions. Using Liouville's theorem, the particle density along the geomagnetic field is determined and found to depend on the local magnetic field, self-consistent electric potential, and the equatorial plasma distribution function. A hot anisotropic magnetospheric plasma in steady state is modeled by a bi-Maxwellian at the equator. The self-consistent electric potential along the magnetic field is calculated assuming quasineutrality, and the potential drop is found to be approximately equal to the average kinetic energy of the equatorially trapped plasma. The potential is compared with that obtained by Alfven and Faelthammar (1963).

X-Ray Absorption Microspectroscopy with Electrostatic Force Microscopy and its Application to Chemical States Mapping

NASA Astrophysics Data System (ADS)

Ishii, M.; Rigopoulos, N.; Poolton, N. R. J.; Hamilton, B.

2007-02-01

A new technique named X-EFM that measures the x-ray absorption fine structure (XAFS) of nanometer objects was developed. In X-EFM, electrostatic force microscopy (EFM) is used as an x-ray absorption detector, and photoionization induced by x-ray absorption of surface electron trapping sites is detected by EFM. An EFM signal with respect to x-ray photon energy provides the XAFS spectra of the trapping sites. We adopted X-EFM to observe Si oxide thin films. An edge jump shift intrinsic to the X-EFM spectrum was found, and it was explained with a model where an electric field between the trapping site and probe deepens the energy level of the inner-shell. A scanning probe under x-rays with fixed photon energy provided the chemical state mapping on the surface.

Towards a wire-mediated coupling of trapped ions

NASA Astrophysics Data System (ADS)

Clark, Robert; Lee, Tony; Daniilidis, Nikos; Sankaranarayanan, S.; Häffner, Hartmut

2008-03-01

Most schemes for ion trap quantum computation rely upon the exchange of information between ion-qubits in the same trap region, mediated by their shared vibrational mode. An alternative way to achieve this coupling is via the image charges induced in a conducting wire that connects different traps. This was shown to be theoretically possible by Heinzen and Wineland in 1990, but some important practical questions have remained unaddressed. Among these are how the presence of such a wire modifies the motional frequencies and heating rates of trapped ions. We thus have realized this system as a 1 mm-scale planar segmented rf ion trap combined with an electrically floating gold wire of 25 microns diameter and length 1 cm. This wire is placed close to trapped ions using a set of piezoelectric nanopositioners. We present here experimental measurements of the motional frequencies and heating rates of a single trapped calcium ion as the wire is moved from 3.0 mm to 0.2 mm away from the ion. We discuss the implications of these results for achieving wire-mediated coupling in the present apparatus, as well as in future improved setups.

Cooling and heating of the quantum motion of trapped cadmium(+) ions

NASA Astrophysics Data System (ADS)

Deslauriers, Louis

The quest for a quantum system best satisfying the stringent requirements of a quantum information processor has made tremendous progress in many fields of physics. In the last decade, trapped ions have been established as one of the most promising architectures to accomplish the task. Internal states of an ion which can have extremely long coherence time can be used to store a quantum bit, and therefore allow many gate operations before the coherence is lost. Entanglement between multiple ions can be established via Coulomb interactions mediated by appropriate laser fields. Entangling schemes usually require the ions to be initialized to near their motional ground state. The interaction of fluctuating electric fields with the motional state of the ion leads to heating and thus to decoherence for entanglement generation limiting the fidelity of quantum logic gates. Effective ground state cooling of trapped ion motion and suppression of motional heating are thus crucial to many applications of trapped ions in quantum information science. In this thesis, I describe the implementation and study of several components of a Cadmium-ion-based quantum information processor, with special emphasis on the control and decoherence of trapped ion motion. I first discuss the building and design of various ion traps that were used in this work. I also report on the use of ultrafast laser pulses to photoionize and load cadmium ions in a variety of rf Paul trap geometries. A detailed analysis of the photoionization scheme is presented, along with its dependence on controlled experimental parameters. I then describe the implementation of Raman sideband cooling on a single trapped 111Cd+ ion to the ground state of motion, where a ground state population of 97% was achieved. The efficacy of this cooling technique is discussed with respect to different initial motional state distributions and its sensitivity to the presence of motional heating. I also present an experiment where the motion of a single trapped 112Cd+ ion is sympathetically cooled by directly Doppler cooling a 114Cd+ ion in the same trap. The implications of this result are relevant to the scaling of a trapped ion quantum computer, where the unwanted motion of an ion crystal can be quenched while not affecting the internal states of the qubit ions. (Abstract shortened by UMI.)

A Linear Ion Trap with an Expanded Inscribed Diameter to Improve Optical Access for Fluorescence Spectroscopy

NASA Astrophysics Data System (ADS)

Rajagopal, Vaishnavi; Stokes, Chris; Ferzoco, Alessandra

2018-02-01

We report a custom-geometry linear ion trap designed for fluorescence spectroscopy of gas-phase ions at ambient to cryogenic temperatures. Laser-induced fluorescence from trapped ions is collected from between the trapping rods, orthogonal to the excitation laser that runs along the axis of the linear ion trap. To increase optical access to the ion cloud, the diameter of the round trapping rods is 80% of the inscribed diameter, rather than the roughly 110% used to approximate purely quadrupolar electric fields. To encompass as much of the ion cloud as possible, the first collection optic has a 25.4 mm diameter and a numerical aperture of 0.6. The choice of geometry and collection optics yields 107 detected photons/s from trapped rhodamine 6G ions. The trap is coupled to a closed-cycle helium refrigerator, which in combination with two 50 Ohm heaters enables temperature control to below 25 K on the rod electrodes. The purpose of the instrument is to broaden the applicability of fluorescence spectroscopy of gas-phase ions to cases where photon emission is a minority relaxation pathway. Such studies are important to understand how the microenvironment of a chromophore influences excited state charge transfer processes.

Ion-neutral-atom sympathetic cooling in a hybrid linear rf Paul and magneto-optical trap

NASA Astrophysics Data System (ADS)

Goodman, D. S.; Sivarajah, I.; Wells, J. E.; Narducci, F. A.; Smith, W. W.

2012-09-01

Long-range polarization forces between ions and neutral atoms result in large elastic scattering cross sections (e.g., ˜106a.u. for Na-Na+ or Na-Ca+ at cold and ultracold temperatures). This suggests that a hybrid ion-neutral trap should offer a general means for significant sympathetic cooling of atomic or molecular ions. We present simion 7.0 simulation results concerning the advantages and limitations of sympathetic cooling within a hybrid trap apparatus consisting of a linear rf Paul trap concentric with a Na magneto-optical trap (MOT). This paper explores the impact of various heating mechanisms on the hybrid system and how parameters related to the MOT, Paul trap, number of ions, and ion species affect the efficiency of the sympathetic cooling.

Magnetized retarding field energy analyzer measuring the particle flux and ion energy distribution of both positive and negative ions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rafalskyi, Dmytro; Aanesland, Ane; Dudin, Stanislav

2015-05-15

This paper presents the development of a magnetized retarding field energy analyzer (MRFEA) used for positive and negative ion analysis. The two-stage analyzer combines a magnetic electron barrier and an electrostatic ion energy barrier allowing both positive and negative ions to be analyzed without the influence of electrons (co-extracted or created downstream). An optimal design of the MRFEA for ion-ion beams has been achieved by a comparative study of three different MRFEA configurations, and from this, scaling laws of an optimal magnetic field strength and topology have been deduced. The optimal design consists of a uniform magnetic field barrier createdmore » in a rectangular channel and an electrostatic barrier consisting of a single grid and a collector placed behind the magnetic field. The magnetic barrier alone provides an electron suppression ratio inside the analyzer of up to 6000, while keeping the ion energy resolution below 5 eV. The effective ion transparency combining the magnetic and electrostatic sections of the MRFEA is measured as a function of the ion energy. It is found that the ion transparency of the magnetic barrier increases almost linearly with increasing ion energy in the low-energy range (below 200 eV) and saturates at high ion energies. The ion transparency of the electrostatic section is almost constant and close to the optical transparency of the entrance grid. We show here that the MRFEA can provide both accurate ion flux and ion energy distribution measurements in various experimental setups with ion beams or plasmas run at low pressure and with ion energies above 10 eV.« less

Deconvolution of Raman spectroscopic signals for electrostatic, H-bonding, and inner-sphere interactions between ions and dimethyl phosphate in solution

PubMed Central

Christian, Eric L; Anderson, Vernon E.; Harris, Michael E

2011-01-01

Quantitative analysis of metal ion-phosphodiester interactions is a significant experimental challenge due to the complexities introduced by inner-sphere, outer-sphere (H-bonding with coordinated water), and electrostatic interactions that are difficult to isolate in solution studies. Here, we provide evidence that inner-sphere, H-bonding and electrostatic interactions between ions and dimethyl phosphate can be deconvoluted through peak fitting in the region of the Raman spectrum for the symmetric stretch of non-bridging phosphate oxygens (νsPO 2-). An approximation of the change in vibrational spectra due to different interaction modes is achieved using ions capable of all or a subset of the three forms of metal ion interaction. Contribution of electrostatic interactions to ion-induced changes to the Raman νsPO2- signal could be modeled by monitoring attenuation of νsPO2- in the presence of tetramethylammonium, while contribution of H-bonding and inner-sphere coordination could be approximated from the intensities of altered νsPO2- vibrational modes created by an interaction with ammonia, monovalent or divalent ions. A model is proposed in which discrete spectroscopic signals for inner-sphere, H-bonding, and electrostatic interactions are sufficient to account for the total observed change in νsPO2- signal due to interaction with a specific ion capable of all three modes of interaction. Importantly, the quantitative results are consistent with relative levels of coordination predicted from absolute electronegativity and absolute hardness of alkali and alkaline earth metals. PMID:21334281

Simulation of electrostatic turbulence in the plasma sheet boundary layer with electron currents and bean-shaped ion beams

NASA Technical Reports Server (NTRS)

Nishikawa, K.-I.; Frank, L. A.; Huang, C. Y.

1988-01-01

Plasma data from ISEE-1 show the presence of electron currents as well as energetic ion beams in the plasma sheet boundary layer. Broadband electrostatic noise and low-frequency electromagnetic bursts are detected in the plasma sheet boundary layer, especially in the presence of strong ion flows, currents, and steep spacial gradients in the fluxes of few-keV electrons and ions. Particle simulations have been performed to investigate electrostatic turbulence driven by a cold electron beam and/or ion beams with a bean-shaped velocity distribution. The simulation results show that the counterstreaming ion beams as well as the counterstreaming of the cold electron beam and the ion beam excite ion acoustic waves with a given Doppler-shifted real frequency. However, the effect of the bean-shaped ion velocity distributions reduces the growth rates of ion acoustic instability. The simulation results also show that the slowing down of the ion bean is larger at the larger perpendicular velocity. The wave spectra of the electric fields at some points of the simulations show turbulence generated by growing waves.

Apparatus for magnetic and electrostatic confinement of plasma

DOEpatents

Rostoker, Norman; Binderbauer, Michl

2013-06-11

An apparatus and method for containing plasma and forming a Field Reversed Configuration (FRC) magnetic topology are described in which plasma ions are contained magnetically in stable, non-adiabatic orbits in the FRC. Further, the electrons are contained electrostatically in a deep energy well, created by tuning an externally applied magnetic field. The simultaneous electrostatic confinement of electrons and magnetic confinement of ions avoids anomalous transport and facilitates classical containment of both electrons and ions. In this configuration, ions and electrons may have adequate density and temperature so that upon collisions ions are fused together by nuclear force, thus releasing fusion energy. Moreover, the fusion fuel plasmas that can be used with the present confinement system and method are not limited to neutronic fuels only, but also advantageously include advanced fuels.

Apparatus for magnetic and electrostatic confinement of plasma

DOEpatents

Rostoker, Norman; Binderbauer, Michl

2016-07-05

An apparatus and method for containing plasma and forming a Field Reversed Configuration (FRC) magnetic topology are described in which plasma ions are contained magnetically in stable, non-adiabatic orbits in the FRC. Further, the electrons are contained electrostatically in a deep energy well, created by tuning an externally applied magnetic field. The simultaneous electrostatic confinement of electrons and magnetic confinement of ions avoids anomalous transport and facilitates classical containment of both electrons and ions. In this configuration, ions and electrons may have adequate density and temperature so that upon collisions ions are fused together by nuclear force, thus releasing fusion energy. Moreover, the fusion fuel plasmas that can be used with the present confinement system and method are not limited to neutronic fuels only, but also advantageously include advanced fuels.

Apparatus for magnetic and electrostatic confinement of plasma

DOEpatents

Rostoker, Norman [Irvine, CA; Binderbauer, Michl [Irvine, CA

2009-08-04

An apparatus and method for containing plasma and forming a Field Reversed Configuration (FRC) magnetic topology are described in which plasma ions are contained magnetically in stable, non-adiabatic orbits in the FRC. Further, the electrons are contained electrostatically in a deep energy well, created by tuning an externally applied magnetic field. The simultaneous electrostatic confinement of electrons and magnetic confinement of ions avoids anomalous transport and facilitates classical containment of both electrons and ions. In this configuration, ions and electrons may have adequate density and temperature so that upon collisions ions are fused together by nuclear force, thus releasing fusion energy. Moreover, the fusion fuel plasmas that can be used with the present confinement system and method are not limited to neutronic fuels only, but also advantageously include advanced fuels.

Scaling Trapped Ion Quantum Computers Using Fast Gates and Microtraps

NASA Astrophysics Data System (ADS)

Ratcliffe, Alexander K.; Taylor, Richard L.; Hope, Joseph J.; Carvalho, André R. R.

2018-06-01

Most attempts to produce a scalable quantum information processing platform based on ion traps have focused on the shuttling of ions in segmented traps. We show that an architecture based on an array of microtraps with fast gates will outperform architectures based on ion shuttling. This system requires higher power lasers but does not require the manipulation of potentials or shuttling of ions. This improves optical access, reduces the complexity of the trap, and reduces the number of conductive surfaces close to the ions. The use of fast gates also removes limitations on the gate time. Error rates of 10-5 are shown to be possible with 250 mW laser power and a trap separation of 100 μ m . The performance of the gates is shown to be robust to the limitations in the laser repetition rate and the presence of many ions in the trap array.

An in situ trap capacitance measurement and ion-trapping detection scheme for a Penning ion trap facility.

PubMed

Reza, Ashif; Banerjee, Kumardeb; Das, Parnika; Ray, Kalyankumar; Bandyopadhyay, Subhankar; Dam, Bivas

2017-03-01

This paper presents the design and implementation of an in situ measurement setup for the capacitance of a five electrode Penning ion trap (PIT) facility at room temperature. For implementing a high Q resonant circuit for the detection of trapped electrons/ions in a PIT, the value of the capacitance of the trap assembly is of prime importance. A tunable Colpitts oscillator followed by a unity gain buffer and a low pass filter is designed and successfully implemented for a two-fold purpose: in situ measurement of the trap capacitance when the electric and magnetic fields are turned off and also providing RF power at the desired frequency to the PIT for exciting the trapped ions and subsequent detection. The setup is tested for the in situ measurement of trap capacitance at room temperature and the results are found to comply with those obtained from measurements using a high Q parallel resonant circuit setup driven by a standard RF signal generator. The Colpitts oscillator is also tested successfully for supplying RF power to the high Q resonant circuit, which is required for the detection of trapped electrons/ions.

On the function and fate of chloride ions in amyloidogenic self-assembly of insulin in an acidic environment: salt-induced condensation of fibrils.

PubMed

Babenko, Viktoria; Surmacz-Chwedoruk, Weronika; Dzwolak, Wojciech

2015-02-24

Formation of amyloid fibrils is often facilitated in the presence of specific charge-compensating ions. Dissolved sodium chloride is known to accelerate insulin fibrillation at low pH that has been attributed to the shielding of electrostatic repulsion between positively charged insulin molecules by chloride ions. However, the subsequent fate of Cl(-) anions; that is, possible entrapment within elongating fibrils or escape into the bulk solvent, remains unclear. Here, we show that, while the presence of NaCl at the onset of insulin aggregation induces structural variants of amyloid with distinct fingerprint infrared features, a delayed addition of salt to fibrils that have been already formed in its absence and under quiescent conditions triggers a "condensation effect": amyloid superstructures with strong chiroptical properties are formed. Chloride ions appear to stabilize these superstructures in a manner similar to stabilization of DNA condensates by polyvalent cations. The concentration of residual chloride ions trapped within bovine insulin fibrils grown in 0.1 M NaCl, at pD 1.9, and rinsed extensively with water afterward is less than 1 anion per 16 insulin monomers (as estimated using ion chromatography) implying absence of defined solvent-sequestered nesting sites for chloride counterions. Our results have been discussed in the context of mechanisms of insulin aggregation.

Cryogenically cooled octupole ion trap for spectroscopy of biomolecular ions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Boyarkin, Oleg V., E-mail: oleg.boiarkin@epfl.ch; Kopysov, Vladimir

2014-03-15

We present here the design of a linear octupole ion trap, suitable for collisional cryogenic cooling and spectroscopy of large ions. The performance of this trap has been assessed using ultraviolet (UV) photofragmentation spectroscopy of protonated dipeptides. At the trap temperature of 6.1 K, the vibrational temperature of the ions reaches 9.1 K, although their estimated translational temperature is ∼150 K. This observation suggests that, despite the significant translational heating by radio-frequency electrical field, vibrational cooling of heavy ions in the octupole is at least as efficient as in the 22-pole ion traps previously used in our laboratory. In contrastmore » to the 22-pole traps, excellent radial confinement of ions in the octupole makes it convenient for laser spectroscopy and boosts the dissociation yield of the stored ions to 30%. Overlap of the entire ion cloud by the laser beam in the octupole also allows for efficient UV depletion spectroscopy of ion–He clusters. The measured electronic spectra of the dipeptides and the clusters differ drastically, complicating a use of UV tagging spectroscopy for structural determination of large species.« less

Ion cyclotron resonance cell

DOEpatents

Weller, Robert R.

1995-01-01

An ion cyclotron resonance cell having two adjacent sections separated by a center trapping plate. The first section is defined by the center trapping plate, a first end trapping plate, and excitation and detector electrodes. The second section includes a second end trapping plate spaced apart from the center plate, a mirror, and an analyzer. The analyzer includes a wavelength-selective light detector, such as a detector incorporating an acousto-optical device (AOD) and a photodetector. One or more ion guides, grounded plates with holes for the ion beam, are positioned within the vacuum chamber of the mass spectrometer between the ion source and the cell. After ions are trapped and analyzed by ion cyclotron resonance techniques in the first section, the ions of interest are selected according to their mass and passed into the second section for optical spectroscopic studies. The trapped ions are excited by light from a laser and caused thereby to fluoresce. The fluorescent light emitted by the excited ions is reflected by the mirror and directed onto the detector. The AOD is scanned, and the photodetector output is recorded and analyzed. The ions remain in the second section for an extended period, enabling multiple studies to be carried out on the same ensemble of ions.

Interchange mode excited by trapped energetic ions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nishimura, Seiya, E-mail: n-seiya@kobe-kosen.ac.jp

2015-07-15

The kinetic energy principle describing the interaction between ideal magnetohydrodynamic (MHD) modes with trapped energetic ions is revised. A model is proposed on the basis of the reduced ideal MHD equations for background plasmas and the bounce-averaged drift-kinetic equation for trapped energetic ions. The model is applicable to large-aspect-ratio toroidal devices. Specifically, the effect of trapped energetic ions on the interchange mode in helical systems is analyzed. Results show that the interchange mode is excited by trapped energetic ions, even if the equilibrium states are stable to the ideal interchange mode. The energetic-ion-induced branch of the interchange mode might bemore » associated with the fishbone mode in helical systems.« less

Electrostatic Estimation of Intercalant Jump-Diffusion Barriers Using Finite-Size Ion Models.

PubMed

Zimmermann, Nils E R; Hannah, Daniel C; Rong, Ziqin; Liu, Miao; Ceder, Gerbrand; Haranczyk, Maciej; Persson, Kristin A

2018-02-01

We report on a scheme for estimating intercalant jump-diffusion barriers that are typically obtained from demanding density functional theory-nudged elastic band calculations. The key idea is to relax a chain of states in the field of the electrostatic potential that is averaged over a spherical volume using different finite-size ion models. For magnesium migrating in typical intercalation materials such as transition-metal oxides, we find that the optimal model is a relatively large shell. This data-driven result parallels typical assumptions made in models based on Onsager's reaction field theory to quantitatively estimate electrostatic solvent effects. Because of its efficiency, our potential of electrostatics-finite ion size (PfEFIS) barrier estimation scheme will enable rapid identification of materials with good ionic mobility.

Ultrafast collisional ion heating by electrostatic shocks.

PubMed

Turrell, A E; Sherlock, M; Rose, S J

2015-11-13

High-intensity lasers can be used to generate shockwaves, which have found applications in nuclear fusion, proton imaging, cancer therapies and materials science. Collisionless electrostatic shocks are one type of shockwave widely studied for applications involving ion acceleration. Here we show a novel mechanism for collisionless electrostatic shocks to heat small amounts of solid density matter to temperatures of ∼keV in tens of femtoseconds. Unusually, electrons play no direct role in the heating and it is the ions that determine the heating rate. Ions are heated due to an interplay between the electric field of the shock, the local density increase during the passage of the shock and collisions between different species of ion. In simulations, these factors combine to produce rapid, localized heating of the lighter ion species. Although the heated volume is modest, this would be one of the fastest heating mechanisms discovered if demonstrated in the laboratory.

Ion Trapping, Storage, and Ejection in Structures for Lossless Ion Manipulations

DOE PAGES

Zhang, Xinyu; Garimella, Sandilya V. B.; Prost, Spencer A.; ...

2015-06-14

Here, a structure for lossless ion manipulation (SLIM) module was constructed with electrode arrays patterned on a pair of parallel printed circuit boards (PCB) separated by 5 mm and utilized to investigate capabilities for ion trapping at 4 Torr. Positive ions were confined by application of RF having alternating phases on a series of inner rung electrodes and by positive DC potentials on surrounding guard electrodes on each PCB. An axial DC field was also introduced by stepwise varying the DC potential of the inner rung electrodes so as to control the ion transport and accumulation inside the ion trap.more » We show that ions could be trapped and accumulated with 100% efficiency, stored for at least 5 hours with no losses, and could be rapidly ejected from the SLIM trap.« less

Turbulent resistivity, diffusion and heating

NASA Technical Reports Server (NTRS)

Fried, B. D.; Kennel, C. F.; Mackenzie, K.; Coroniti, F. V.; Kindel, J. M.; Stenzel, R.; Taylor, R. J.; White, R.; Wong, A. Y.; Bernstein, W.

1971-01-01

Experimental and theoretical studies are reported on ion acoustic and ion cyclotron turbulence and their roles in anomalous resistivity, viscosity, diffusion and heating and in the structure of collisionless electrostatic shocks. Resistance due to ion acoustic turbulence has been observed in experiments with a streaming cesium plasma in which electron current, potential rise due to turbulent resistivity, spectrum of unstable ion acoustic waves, and associated electron heating were all measured directly. Kinetic theory calculations for an expanding, unstable plasma, give results in agreement with the experiment. In a strong magnetic field, with T sub e/T sub i approximately 1 and current densities typical for present Tokomaks, the plasma is stable to ion acoustic but unstable to current driven electrostatic ion cyclotron waves. Relevant characteristics of these waves are calculated and it is shown that for ion, beta greater than m sub e/m sub i, the electromagnetic ion cyclotron wave has a lower instability threshold than the electrostatic one. However, when ion acoustic turbulence is present experiments with double plasma devices show rapid anomalous heating of an ion beam streaming through a plasma.

METHOD AND APPARATUS FOR TRAPPING IONS IN A MAGNETIC FIELD

DOEpatents

Luce, J.S.

1962-04-17

A method and apparatus are described for trapping ions within an evacuated container and within a magnetic field utilizing dissociation and/or ionization of molecular ions to form atomic ions and energetic neutral particles. The atomic ions are magnetically trapped as a result of a change of charge-to- mass ratio. The molecular ions are injected into the container and into the path of an energetic carbon arc discharge which dissociates and/or ionizes a portion of the molecular ions into atomic ions and energetic neutrals. The resulting atomic ions are trapped by the magnetic field to form a circulating beam of atomic ions, and the energetic neutrals pass out of the system and may be utilized in a particle accelerator. (AEC)

Ion funnel ion trap and process

DOEpatents

Belov, Mikhail E [Richland, WA; Ibrahim, Yehia M [Richland, WA; Clowers, Biran H [West Richland, WA; Prior, David C [Hermiston, OR; Smith, Richard D [Richland, WA

2011-02-15

An ion funnel trap is described that includes a inlet portion, a trapping portion, and a outlet portion that couples, in normal operation, with an ion funnel. The ion trap operates efficiently at a pressure of .about.1 Torr and provides for: 1) removal of low mass-to-charge (m/z) ion species, 2) ion accumulation efficiency of up to 80%, 3) charge capacity of .about.10,000,000 elementary charges, 4) ion ejection time of 40 to 200 .mu.s, and 5) optimized variable ion accumulation times. Ion accumulation with low concentration peptide mixtures has shown an increase in analyte signal-to-noise ratios (SNR) of a factor of 30, and a greater than 10-fold improvement in SNR for multiply charged analytes.

Shaping of nested potentials for electron cooling of highly-charged ions in a cooler Penning trap

NASA Astrophysics Data System (ADS)

Paul, Stefan; Kootte, Brian; Lascar, Daniel; Gwinner, Gerald; Dilling, Jens; Titan Collaboration

2016-09-01

TRIUMF's Ion Trap for Atomic and Nuclear science (TITAN) is dedicated to mass spectrometry and decay spectroscopy of short-lived radioactive nuclides in a series of ion traps including a precision Penning trap. In order to boost the achievable precision of mass measurements TITAN deploys an Electron Beam Ion Trap (EBIT) providing Highly-Charged Ions (HCI). However, the charge breeding process in the EBIT leads to an increase in the ion bunch's energy spread which is detrimental to the overall precision gain. To reduce this effect a new cylindrical Cooler PEnning Trap (CPET) is being commissioned to sympathetically cool the HCI via a simultaneously trapped electron plasma. Simultaneous trapping of ions and electrons requires a high level of control over the nested potential landscape and sophisticated switching schemes for the voltages on CPET's multiple ring electrodes. For this purpose, we are currently setting up a new experimental control system for multi-channel voltage switching. The control system employs a Raspberry Pi communicating with a digital-to-analog board via a serial peripheral interface. We report on the implementation of the voltage control system and its performance with respect to electron and ion manipulation in CPET. University of British Columbia, Vancouver, BC, Canada.

Kinetic simulation of edge instability in fusion plasmas

NASA Astrophysics Data System (ADS)

Fulton, Daniel Patrick

In this work, gyrokinetic simulations in edge plasmas of both tokamaks and field reversed. configurations (FRC) have been carried out using the Gyrokinetic Toroidal Code (GTC) and A New Code (ANC) has been formulated for cross-separatrix FRC simulation. In the tokamak edge, turbulent transport in the pedestal of an H-mode DIII-D plasma is. studied via simulations of electrostatic driftwaves. Annulus geometry is used and simulations focus on two radial locations corresponding to the pedestal top with mild pressure gradient and steep pressure gradient. A reactive trapped electron instability with typical ballooning mode structure is excited in the pedestal top. At the steep gradient, the electrostatic instability exhibits unusual mode structure, peaking at poloidal angles theta=+- pi/2. Simulations find this unusual mode structure is due to steep pressure gradients in the pedestal but not due to the particular DIII-D magnetic geometry. Realistic DIII-D geometry has a stabilizing effect compared to a simple circular tokamak geometry. Driftwave instability in FRC is studied for the first time using gyrokinetic simulation. GTC. is upgraded to treat realistic equilibrium calculated by an MHD equilibrium code. Electrostatic local simulations in outer closed flux surfaces find ion-scale modes are stable due to the large ion gyroradius and that electron drift-interchange modes are excited by electron temperature gradient and bad magnetic curvature. In the scrape-off layer (SOL) ion-scale modes are excited by density gradient and bad curvature. Collisions have weak effects on instabilities both in the core and SOL. Simulation results are consistent with density fluctuation measurements in the C-2 experiment using Doppler backscattering (DBS). The critical density gradients measured by the DBS qualitatively agree with the linear instability threshold calculated by GTC simulations. One outstanding critical issue in the FRC is the interplay between turbulence in the FRC. core and SOL regions. While the magnetic flux coordinates used by GTC provide a number of computational advantages, they present unique challenges at the magnetic field separatrix. To address this limitation, a new code, capable of coupled core-SOL simulations, is formulated, implemented, and successfully verified.

Gated charged-particle trap

DOEpatents

Benner, W.H.

1999-03-09

The design and operation of a new type of charged-particle trap provides simultaneous measurements of mass, charge, and velocity of large electrospray ions. The trap consists of a detector tube mounted between two sets of center-bored trapping plates. Voltages applied to the trapping plates define symmetrically-opposing potential valleys which guide axially-injected ions to cycle back and forth through the charge-detection tube. A low noise charge-sensitive amplifier, connected to the tube, reproduces the image charge of individual ions as they pass through the detector tube. Ion mass is calculated from measurement of ion charge and velocity following each passage through the detector. 5 figs.

Oxford ion-trap quantum computing project.

PubMed

Lucas, D M; Donald, C J S; Home, J P; McDonnell, M J; Ramos, A; Stacey, D N; Stacey, J-P; Steane, A M; Webster, S C

2003-07-15

We describe recent progress in the development of an ion-trap quantum information processor. We discuss the choice of ion species and describe recent experiments on read-out for a ground-state qubit and photoionization trap loading.

Active stabilization of ion trap radiofrequency potentials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, K. G.; Wong-Campos, J. D.; Restelli, A.

2016-05-15

We actively stabilize the harmonic oscillation frequency of a laser-cooled atomic ion confined in a radiofrequency (rf) Paul trap by sampling and rectifying the high voltage rf applied to the trap electrodes. We are able to stabilize the 1 MHz atomic oscillation frequency to be better than 10 Hz or 10 ppm. This represents a suppression of ambient noise on the rf circuit by 34 dB. This technique could impact the sensitivity of ion trap mass spectrometry and the fidelity of quantum operations in ion trap quantum information applications.

Low Mach-number collisionless electrostatic shocks and associated ion acceleration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pusztai, Istvan; TenBarge, Jason; Csapó, Aletta N.

The existence and properties of low Mach-number (M >~ 1) electrostatic collisionless shocks are investigated with a semi-analytical solution for the shock structure. We show that the properties of the shock obtained in the semi-analytical model can be well reproduced in fully kinetic Eulerian Vlasov-Poisson simulations, where the shock is generated by the decay of an initial density discontinuity. By using this semi-analytical model, we also study the effect of electron-to-ion temperature ratio and presence of impurities on both the maximum shock potential and Mach number. We find that even a small amount of impurities can influence the shock propertiesmore » significantly, including the reflected light ion fraction, which can change several orders of magnitude. Electrostatic shocks in heavy ion plasmas reflect most of the hydrogen impurity ions.« less

Low Mach-number collisionless electrostatic shocks and associated ion acceleration

DOE PAGES

Pusztai, Istvan; TenBarge, Jason; Csapó, Aletta N.; ...

2017-12-19

The existence and properties of low Mach-number (M >~ 1) electrostatic collisionless shocks are investigated with a semi-analytical solution for the shock structure. We show that the properties of the shock obtained in the semi-analytical model can be well reproduced in fully kinetic Eulerian Vlasov-Poisson simulations, where the shock is generated by the decay of an initial density discontinuity. By using this semi-analytical model, we also study the effect of electron-to-ion temperature ratio and presence of impurities on both the maximum shock potential and Mach number. We find that even a small amount of impurities can influence the shock propertiesmore » significantly, including the reflected light ion fraction, which can change several orders of magnitude. Electrostatic shocks in heavy ion plasmas reflect most of the hydrogen impurity ions.« less

Ion mass spectrometer

NASA Technical Reports Server (NTRS)

Neugebauer, M. (Inventor); Clay, D. R.; Goldstein, B. E.; Goldstein, R.

1984-01-01

An ion mass spectrometer is described which detects and indicates the characteristics of ions received over a wide angle, and which indicates the mass to charge ratio, the energy, and the direction of each detected ion. The spectrometer includes a magnetic analyzer having a sector magnet that passes ions received over a wide angle, and an electrostatic analyzer positioned to receive ions passing through the magnetic analyzer. The electrostatic analyzer includes a two dimensional ion sensor at one wall of the analyzer chamber, that senses not only the lengthwise position of the detected ion to indicate its mass to charge ratio, but also detects the ion position along the width of the chamber to indicate the direction in which the ion was traveling.

Reduction of Trapped-Ion Anomalous Heating by in situ Surface Plasma Cleaning

DTIC Science & Technology

2015-04-29

the trap chip temperature. To load ions, we initially cool 88Sr atoms into a remotely-located magneto - optical trap (MOT), then use a resonant push beam... trap heating rates [10]. Furthermore, some previous experiments have shown an improvement in the heating rates of surface-electrode ion traps after...rate when the trap chip is held at 4 K is not significantly improved by the plasma cleaning. While the observed frequency scaling is not the same in

HITRAP: A Facility for Experiments with Trapped Highly Charged Ions

NASA Astrophysics Data System (ADS)

Quint, W.; Dilling, J.; Djekic, S.; Häffner, H.; Hermanspahn, N.; Kluge, H.-J.; Marx, G.; Moore, R.; Rodriguez, D.; Schönfelder, J.; Sikler, G.; Valenzuela, T.; Verdú, J.; Weber, C.; Werth, G.

2001-01-01

HITRAP is a planned ion trap facility for capturing and cooling of highly charged ions produced at GSI in the heavy-ion complex of the UNILAC-SIS accelerators and the ESR storage ring. In this facility heavy highly charged ions up to uranium will be available as bare nuclei, hydrogen-like ions or few-electron systems at low temperatures. The trap for receiving and studying these ions is designed for operation at extremely high vacuum by cooling to cryogenic temperatures. The stored highly charged ions can be investigated in the trap itself or can be extracted from the trap at energies up to about 10 keV/q. The proposed physics experiments are collision studies with highly charged ions at well-defined low energies (eV/u), high-accuracy measurements to determine the g-factor of the electron bound in a hydrogen-like heavy ion and the atomic binding energies of few-electron systems, laser spectroscopy of HFS transitions and X-ray spectroscopy.

Second order kinetic theory of parallel momentum transport in collisionless drift wave turbulence

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Yang, E-mail: lyang13@mails.tsinghua.edu.cn; Southwestern Institute of Physics, Chengdu 610041; Gao, Zhe

A second order kinetic model for turbulent ion parallel momentum transport is presented. A new nonresonant second order parallel momentum flux term is calculated. The resonant component of the ion parallel electrostatic force is the momentum source, while the nonresonant component of the ion parallel electrostatic force compensates for that of the nonresonant second order parallel momentum flux. The resonant component of the kinetic momentum flux can be divided into three parts, including the pinch term, the diffusive term, and the residual stress. By reassembling the pinch term and the residual stress, the residual stress can be considered as amore » pinch term of parallel wave-particle resonant velocity, and, therefore, may be called as “resonant velocity pinch” term. Considering the resonant component of the ion parallel electrostatic force is the transfer rate between resonant ions and waves (or, equivalently, nonresonant ions), a conservation equation of the parallel momentum of resonant ions and waves is obtained.« less

Versatile Optical Bench for Teaching, Development, and Testing of Electron and Ion Optical Systems

ERIC Educational Resources Information Center

Bhiday, M. R.; And Others

1977-01-01

Describes a versatile apparatus for demonstrating the imaging properties of various types of electrostatic lenses. The apparatus can be used to study the focusing properties of different types of electrostatic electron or ion lenses or their combinations. (MLH)

Comprehensive Materials and Morphologies Study of Ion Traps (COMMIT) for Scalable Quantum Computation

DTIC Science & Technology

2012-04-21

the photoelectric effect. The typical shortest wavelengths needed for ion traps range from 194 nm for Hg+ to 493 nm for Ba +, corresponding to 6.4-2.5...REPORT Comprehensive Materials and Morphologies Study of Ion Traps (COMMIT) for scalable Quantum Computation - Final Report 14. ABSTRACT 16. SECURITY...CLASSIFICATION OF: Trapped ion systems, are extremely promising for large-scale quantum computation, but face a vexing problem, with motional quantum

Ion cyclotron resonance cell

DOEpatents

Weller, R.R.

1995-02-14

An ion cyclotron resonance cell is disclosed having two adjacent sections separated by a center trapping plate. The first section is defined by the center trapping plate, a first end trapping plate, and excitation and detector electrodes. The second section includes a second end trapping plate spaced apart from the center plate, a mirror, and an analyzer. The analyzer includes a wavelength-selective light detector, such as a detector incorporating an acousto-optical device (AOD) and a photodetector. One or more ion guides, grounded plates with holes for the ion beam, are positioned within the vacuum chamber of the mass spectrometer between the ion source and the cell. After ions are trapped and analyzed by ion cyclotron resonance techniques in the first section, the ions of interest are selected according to their mass and passed into the second section for optical spectroscopic studies. The trapped ions are excited by light from a laser and caused thereby to fluoresce. The fluorescent light emitted by the excited ions is reflected by the mirror and directed onto the detector. The AOD is scanned, and the photodetector output is recorded and analyzed. The ions remain in the second section for an extended period, enabling multiple studies to be carried out on the same ensemble of ions. 5 figs.

Control of the conformations of ion Coulomb crystals in a Penning trap

PubMed Central

Mavadia, Sandeep; Goodwin, Joseph F.; Stutter, Graham; Bharadia, Shailen; Crick, Daniel R.; Segal, Daniel M.; Thompson, Richard C.

2013-01-01

Laser-cooled atomic ions form ordered structures in radiofrequency ion traps and in Penning traps. Here we demonstrate in a Penning trap the creation and manipulation of a wide variety of ion Coulomb crystals formed from small numbers of ions. The configuration can be changed from a linear string, through intermediate geometries, to a planar structure. The transition from a linear string to a zigzag geometry is observed for the first time in a Penning trap. The conformations of the crystals are set by the applied trap potential and the laser parameters, and agree with simulations. These simulations indicate that the rotation frequency of a small crystal is mainly determined by the laser parameters, independent of the number of ions and the axial confinement strength. This system has potential applications for quantum simulation, quantum information processing and tests of fundamental physics models from quantum field theory to cosmology. PMID:24096901

High Power HF Excitation of Low Frequency Stimulated Electrostatic Waves in the Ionospheric Plasma over HAARP

NASA Astrophysics Data System (ADS)

Bernhardt, Paul; Selcher, Craig A.

High Power electromagnetic (EM) waves transmitted from the HAARP facility in Alaska can excite low frequency electrostatic waves by several processes including (1) direct magnetized stimulated Brillouin scatter (MSBS) and (2) parametric decay of high frequency electrostatic waves into electron and ion Bernstein waves. Either an ion acoustic (IA) wave with a frequency less than the ion cyclotron frequency (fCI) or an electrostatic ion cyclotron (EIC) wave just above fCI can be produced by MSBS. The coupled equations describing the MSBS instabil-ity show that the production of both IA and EIC waves is strongly influenced by the wave propagation direction relative to the background magnetic field. Experimental observations of stimulated electromagnetic emissions (SEE) using the HAARP transmitter in Alaska have confirmed the theoretical predictions that only IA waves are excited for propagation along the magnetic zenith and that EIC waves can only be detected with oblique propagation angles. The electron temperature in the heated plasma is obtained from the IA spectrum offsets from the pump frequency. The ion composition can be determined from the measured EIC frequency. Near the second harmonic of the electron cyclotron frequency, the EM pump wave is converted into an electron Bernstein (EB) wave that decays into another EB wave and an ion Bernstein (IB) wave. Strong cyclotron resonance with the EB wave leads to acceleration of the electrons. Ground based SEE observations are related to the theory of low-frequency electrostatic wave generation.

Space-time crystals of trapped ions.

PubMed

Li, Tongcang; Gong, Zhe-Xuan; Yin, Zhang-Qi; Quan, H T; Yin, Xiaobo; Zhang, Peng; Duan, L-M; Zhang, Xiang

2012-10-19

Spontaneous symmetry breaking can lead to the formation of time crystals, as well as spatial crystals. Here we propose a space-time crystal of trapped ions and a method to realize it experimentally by confining ions in a ring-shaped trapping potential with a static magnetic field. The ions spontaneously form a spatial ring crystal due to Coulomb repulsion. This ion crystal can rotate persistently at the lowest quantum energy state in magnetic fields with fractional fluxes. The persistent rotation of trapped ions produces the temporal order, leading to the formation of a space-time crystal. We show that these space-time crystals are robust for direct experimental observation. We also study the effects of finite temperatures on the persistent rotation. The proposed space-time crystals of trapped ions provide a new dimension for exploring many-body physics and emerging properties of matter.

Reflected Charged Particle Populations around Dipolar Lunar Magnetic Anomalies

NASA Astrophysics Data System (ADS)

Deca, Jan; Divin, Andrey

2016-10-01

In this work we analyze and compare the reflected particle populations for both a horizontal and a vertical dipole model embedded in the lunar surface, representing the solar wind interaction with two different lunar magnetic anomaly (LMA) structures. Using the 3D full-kinetic electromagnetic code iPic3D, in combination with a test-particle approach to generate particle trajectories, we focus on the ion and electron dynamics. Whereas the vertical model electrostatically reflects ions upward under both near-parallel and near-perpendicular angles with respect to the lunar surface, the horizontal model only has a significant shallow component. Characterizing the electron dynamics, we find that the interplay of the mini-magnetosphere electric and magnetic fields is capable of temporarily trapping low-energy electrons and possibly ejecting them upstream. Our results are in agreement with recent high-resolution observations. Low- to medium-altitude ion and electron observations might be excellent indicators to complement orbital magnetic field measurements and better uncover the underlying magnetic field structure. The latter is of particular importance in defining the correlation between LMAs and lunar swirls, and further testing the solar wind shielding hypothesis for albedo markings due to space weathering. Observing more reflected ions does not necessarily point to the existence of a mini-magnetosphere.

REFLECTED CHARGED PARTICLE POPULATIONS AROUND DIPOLAR LUNAR MAGNETIC ANOMALIES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Deca, Jan; Divin, Andrey

2016-10-01

In this work we analyze and compare the reflected particle populations for both a horizontal and a vertical dipole model embedded in the lunar surface, representing the solar wind interaction with two different lunar magnetic anomaly (LMA) structures. Using the 3D full-kinetic electromagnetic code iPic3D, in combination with a test-particle approach to generate particle trajectories, we focus on the ion and electron dynamics. Whereas the vertical model electrostatically reflects ions upward under both near-parallel and near-perpendicular angles with respect to the lunar surface, the horizontal model only has a significant shallow component. Characterizing the electron dynamics, we find that themore » interplay of the mini-magnetosphere electric and magnetic fields is capable of temporarily trapping low-energy electrons and possibly ejecting them upstream. Our results are in agreement with recent high-resolution observations. Low- to medium-altitude ion and electron observations might be excellent indicators to complement orbital magnetic field measurements and better uncover the underlying magnetic field structure. The latter is of particular importance in defining the correlation between LMAs and lunar swirls, and further testing the solar wind shielding hypothesis for albedo markings due to space weathering. Observing more reflected ions does not necessarily point to the existence of a mini-magnetosphere.« less

Fast separation of two trapped ions (Open Access, Publisher’s Version)

DTIC Science & Technology

2015-09-17

of quantum states and separation of ions in a dual rf ion trapQuantum Inf. Comput . 2 257 [10] KaufmannH, Ruster T, SchmiegelowCT, Schmidt-Kaler F...Ruschhaupt et al. Shortcuts to adiabaticity for an ion in a rotating radially-tight trap M Palmero, Shuo Wang, D Guéry-Odelin et al. Optimal shortcuts for...Kiely, J P L McGuinness, J G Muga et al. Quantum simulations with cold trapped ions Michael Johanning, Andrés F Varón and Christof Wunderlich Quantum

Scalable Loading of a Two-Dimensional Trapped-Ion Array

DTIC Science & Technology

2015-11-25

ion -trap array based on two crossed photo-ionization laser beams . With the use of a continuous flux of pre-cooled neutral...push laser Atomic beam Dierential pumping tube Push laser 2D-MOT 50 K Shield 4 K Shield 4 K stage Trap chip MOT laser Ion To ion pump 5s2 1S0 461...conducted a series of Ramsey experiments on a single trapped ion in the presence and absence of neu- tral atom flux as well as each of the PI laser

Demonstrating the Principle of an rf Paul Ion Trap

NASA Astrophysics Data System (ADS)

Johnson, Andrew; Rabchuk, James

2008-03-01

An rf ion trap uses a time-varying electric field to trap charged ions. This is useful in applications related to quantum computing and mass spectroscopy. There are several mechanical devices described in the literature which have attempted to provide illustrative demonstrations of the principle of rf ion traps, including a mechanically-rotating ``saddle trap'' and the vertically-driven, inverted pendulum^1,2. Neither demonstration, however, successfully demonstrates BOTH the sinusoidal variation in the electric potential of the rf trap AND the parametric stability of the ions in the trap described by Mathieu's equation. We have modified a design of a one-dimensional ponderomotive trap^3 so that it satisfies both criteria for demonstrating the principle of an rf Paul trap. Our studies indicate that trapping stability is highly sensitive to fluxuations in the driving frequency. Results from the demonstration apparatus constructed by the authors will be presented. ^1 Rueckner, W., et al., ``Rotating saddle Paul trap,'' Am. J. Phys., 63 (2), February 1995. ^2 Friedman, M.H., et al., ``The inverted pendulum: A mechanical analogue of a quadrupole mass filter,'' Am. J. Phys., 50 (10), October 1982. ^3 Johnson, A.K. and Rabchuk, J.A., ``A One-Dimensional Ponderomotive Trap,'' ISAAPT 2007 spring meeting, WIU, March 30, 2007.

Fluorescence spectroscopy of trapped molecular ions

NASA Astrophysics Data System (ADS)

Wright, Kenneth Charles

This thesis describes the development of a unique instrument capable of detecting fluorescence emission from large gas phase molecular ions trapped in a three-dimensional quadrupole ion trap. The hypothesis that has formed the basis of this work is the belief that fluorescence spectroscopy can be combined with ion trap mass spectrometry to probe the structure of gas phase molecular ions. The ion trap provides a rarefied environment where fluorescence experiments can be conducted without interference from solvent molecules or impurities. Although fluorescence was not detected during preliminary experiments, two significant experimental challenges associated with detecting the gas phase fluorescence of ions were discovered. First, gas phase ions were vulnerable to photodissociation and low laser powers were necessary to avoid photodissociation. Since fluorescence emission is directly proportional to laser intensity, a lower laser power limits the fluorescence signal. Second, the fluorescence emission was not significantly Stokes shifted from the excitation. The lack of Stokes shift meant the small fluorescence signal must be detected in the presence of a large amount of background scatter generated by the excitation. Initially, this background was seven orders of magnitude higher than the analytical signal ultimately detected. A specially designed fiber optic probe was inserted between the electrodes of the ion trap to stop light scattered off the outside surfaces of the trap from reaching the detector. The inside surfaces of the ion trap were coated black to further reduce the amount of scattered light collected. These innovations helped reduced the background by six orders of magnitude and fluorescence emission from rhodamine-6G was detected. Pulse counting experiments were used to optimize fluorescence detection. The effects of trapping level, laser power, and irradiation time were investigated and optimized. The instrument developed in this work not only allows for the detection of fluorescent photons, but the sensitivity is high enough for the light to be dispersed and an emission spectrum recorded. The emission spectra of rhodamine-6G and 5-carboxyrhodamine-6G ions reported in this thesis represent the first spectra recorded from large molecular ions confined in a quadrupole ion trap. Finally, anti-Stokes fluorescence from rhodamine-6G was also detected.

MASS SPECTROMETER

DOEpatents

White, F.A.

1960-08-23

A mass spectrometer is designed with a first adjustable magnetic field for resolving an ion beam into beams of selected masses, a second adjustable magnetic field for further resolving the ion beam from the first field into beams of selected masses, a thin foil disposed in the path of the beam between the first and second magnets to dissociate molecular ions incident thereon, an electrostatic field for further resolving the ion beam from the second field into beams of selected masses, and a detector disposed adjacent to the electrostatic field to receive the ion beam.

Low-cost label-free electrical detection of artificial DNA nanostructures using solution-processed oxide thin-film transistors.

PubMed

Kim, Si Joon; Jung, Joohye; Lee, Keun Woo; Yoon, Doo Hyun; Jung, Tae Soo; Dugasani, Sreekantha Reddy; Park, Sung Ha; Kim, Hyun Jae

2013-11-13

A high-sensitivity, label-free method for detecting deoxyribonucleic acid (DNA) using solution-processed oxide thin-film transistors (TFTs) was developed. Double-crossover (DX) DNA nanostructures with different concentrations of divalent Cu ion (Cu(2+)) were immobilized on an In-Ga-Zn-O (IGZO) back-channel surface, which changed the electrical performance of the IGZO TFTs. The detection mechanism of the IGZO TFT-based DNA biosensor is attributed to electron trapping and electrostatic interactions caused by negatively charged phosphate groups on the DNA backbone. Furthermore, Cu(2+) in DX DNA nanostructures generates a current path when a gate bias is applied. The direct effect on the electrical response implies that solution-processed IGZO TFTs could be used to realize low-cost and high-sensitivity DNA biosensors.

Computer simulations of ions in radio-frequency traps

NASA Technical Reports Server (NTRS)

Williams, A.; Prestage, J. D.; Maleki, L.; Djomehri, J.; Harabetian, E.

1990-01-01

The motion of ions in a trapped-ion frequency standard affects the stability of the standard. In order to study the motion and structures of large ion clouds in a radio-frequency (RF) trap, a computer simulation of the system that incorporates the effect of thermal excitation of the ions was developed. Results are presented from the simulation for cloud sizes up to 512 ions, emphasizing cloud structures in the low-temperature regime.

Mechanism of sodium channel block by local anesthetics, antiarrhythmics, and anticonvulsants

PubMed Central

Tikhonov, Denis B.

2017-01-01

Local anesthetics, antiarrhythmics, and anticonvulsants include both charged and electroneutral compounds that block voltage-gated sodium channels. Prior studies have revealed a common drug-binding region within the pore, but details about the binding sites and mechanism of block remain unclear. Here, we use the x-ray structure of a prokaryotic sodium channel, NavMs, to model a eukaryotic channel and dock representative ligands. These include lidocaine, QX-314, cocaine, quinidine, lamotrigine, carbamazepine (CMZ), phenytoin, lacosamide, sipatrigine, and bisphenol A. Preliminary calculations demonstrated that a sodium ion near the selectivity filter attracts electroneutral CMZ but repels cationic lidocaine. Therefore, we further docked electroneutral and cationic drugs with and without a sodium ion, respectively. In our models, all the drugs interact with a phenylalanine in helix IVS6. Electroneutral drugs trap a sodium ion in the proximity of the selectivity filter, and this same site attracts the charged group of cationic ligands. At this position, even small drugs can block the permeation pathway by an electrostatic or steric mechanism. Our study proposes a common pharmacophore for these diverse drugs. It includes a cationic moiety and an aromatic moiety, which are usually linked by four bonds. PMID:28258204

Mechanism of sodium channel block by local anesthetics, antiarrhythmics, and anticonvulsants.

PubMed

Tikhonov, Denis B; Zhorov, Boris S

2017-04-03

Local anesthetics, antiarrhythmics, and anticonvulsants include both charged and electroneutral compounds that block voltage-gated sodium channels. Prior studies have revealed a common drug-binding region within the pore, but details about the binding sites and mechanism of block remain unclear. Here, we use the x-ray structure of a prokaryotic sodium channel, NavMs, to model a eukaryotic channel and dock representative ligands. These include lidocaine, QX-314, cocaine, quinidine, lamotrigine, carbamazepine (CMZ), phenytoin, lacosamide, sipatrigine, and bisphenol A. Preliminary calculations demonstrated that a sodium ion near the selectivity filter attracts electroneutral CMZ but repels cationic lidocaine. Therefore, we further docked electroneutral and cationic drugs with and without a sodium ion, respectively. In our models, all the drugs interact with a phenylalanine in helix IVS6. Electroneutral drugs trap a sodium ion in the proximity of the selectivity filter, and this same site attracts the charged group of cationic ligands. At this position, even small drugs can block the permeation pathway by an electrostatic or steric mechanism. Our study proposes a common pharmacophore for these diverse drugs. It includes a cationic moiety and an aromatic moiety, which are usually linked by four bonds. © 2017 Tikhonov and Zhorov.

Predicting Electrostatic Forces in RNA Folding

PubMed Central

Tan, Zhi-Jie; Chen, Shi-Jie

2016-01-01

Metal ion-mediated electrostatic interactions are critical to RNA folding. Although considerable progress has been made in mechanistic studies, the problem of accurate predictions for the ion effects in RNA folding remains unsolved, mainly due to the complexity of several potentially important issues such as ion correlation and dehydration effects. In this chapter, after giving a brief overview of the experimental findings and theoretical approaches, we focus on a recently developed new model, the tightly bound ion (TBI) model, for ion electrostatics in RNA folding. The model is unique because it can treat ion correlation and fluctuation effects for realistic RNA 3D structures. For monovalent ion (such as Na+) solutions, where ion correlation is weak, TBI and the Poisson–Boltzmann (PB) theory give the same results and the results agree with the experimental data. For multivalent ion (such as Mg2+) solutions, where ion correlation can be strong, however, TBI gives much improved predictions than the PB. Moreover, the model suggests an ion correlation- induced mechanism for the unusual efficiency of Mg2+ ions in the stabilization of RNA tertiary folds. In this chapter, after introducing the theoretical framework of the TBI model, we will describe how to apply the model to predict ion-binding properties and ion-dependent folding stabilities. PMID:20946803

Generalized Dicke Nonequilibrium Dynamics in Trapped Ions

NASA Astrophysics Data System (ADS)

Genway, Sam; Li, Weibin; Ates, Cenap; Lanyon, Benjamin P.; Lesanovsky, Igor

2014-01-01

We explore trapped ions as a setting to investigate nonequilibrium phases in a generalized Dicke model of dissipative spins coupled to phonon modes. We find a rich dynamical phase diagram including superradiantlike regimes, dynamical phase coexistence, and phonon-lasing behavior. A particular advantage of trapped ions is that these phases and transitions among them can be probed in situ through fluorescence. We demonstrate that the main physical insights are captured by a minimal model and consider an experimental realization with Ca+ ions trapped in a linear Paul trap with a dressing scheme to create effective two-level systems with a tunable dissipation rate.

Enhanced polymer capture speed and extended translocation time in pressure-solvation traps

NASA Astrophysics Data System (ADS)

Buyukdagli, Sahin

2018-06-01

The efficiency of nanopore-based biosequencing techniques requires fast anionic polymer capture by like-charged pores followed by a prolonged translocation process. We show that this condition can be achieved by setting a pressure-solvation trap. Polyvalent cation addition to the KCl solution triggers the like-charge polymer-pore attraction. The attraction speeds-up the pressure-driven polymer capture but also traps the molecule at the pore exit, reducing the polymer capture time and extending the polymer escape time by several orders of magnitude. By direct comparison with translocation experiments [D. P. Hoogerheide et al., ACS Nano 8, 7384 (2014), 10.1021/nn5025829], we characterize as well the electrohydrodynamics of polymers transport in pressure-voltage traps. We derive scaling laws that can accurately reproduce the pressure dependence of the experimentally measured polymer translocation velocity and time. We also find that during polymer capture, the electrostatic barrier on the translocating molecule slows down the liquid flow. This prediction identifies the streaming current measurement as a potential way to probe electrostatic polymer-pore interactions.

Towards Quantum Simulations Using a Chip Ion Trap

NASA Astrophysics Data System (ADS)

Cao, Chenglin; Wright, Ken; Brennan, Daniel; Ji, Geoffrey; Monroe, Christopher

2013-05-01

We report our current experimental progress towards using chip ion traps for quantum simulation. Current progress is being made using a micro-fabricated symmetric trap from GTRI. This trap implements a novel two level design that combines the benefits of both surface traps and linear four-rod traps. The trap has 50 electrodes which allow for the fine control of the DC potential needed to create large anharmonic potentials, to join and split ion chains and to shuttle ions along the trapping axis similar to many surface traps. However this trap also has a much deeper trapping depth than conventional surface traps and improved optical access via an angled slot through the chip wide enough to accommodate higher power laser light which could cause surface charging or damage in a traditional chip trap. These advantages should allow trapping of long ion chains. We hope to use these features as the next step in increasing the size of current quantum simulations being done at Univ of Maryland, which are aimed at exploring quantum phenomena in spin systems in a regime inaccessible to classical simulation. This work is supported by grants from the U.S. Army Research Office with funding from the DARPA OLE program, IARPA, and the MURI program; and the NSF Physics Frontier Center at JQI. We acknowledge the GTRI team of J. Amini, K. Brown, A. Harter, F. Shaikh, R. Slusher, and C. Volin for the fabrication of the trap.

Plasma waves produced by the xenon ion beam experiment on the Porcupine sounding rocket

NASA Technical Reports Server (NTRS)

Kintner, P. M.; Kelley, M.

1982-01-01

The production of electrostatic ion cyclotron waves by a perpendicular ion beam in the F-region ionosphere is described. The ion beam experiment was part of the Porcupine program and produced electrostatic hydrogen cyclotron waves just above harmonics of the hydrogen cyclotron frequency. The plasma process may be thought of as a magnetized background ionosphere through which an unmagnetized beam is flowing. The dispersion equation for this hypothesis is constructed and solved. Preliminary solutions agree well with the observed plasma waves.

Progress Report on the Improved Linear Ion Trap Physics Package

NASA Technical Reports Server (NTRS)

Prestage, John D.

1995-01-01

This article describes the first operational results from the extended linear ion trap frequency standard now being developed at JPL. This new design separates the state selection/interrogation region from the more critical microwave resonance region where the multiplied local oscillator (LO) signal is compared to the stable atomic transition. Hg+ ions have been trapped, shuttled back and forth between the resonance and state selection traps. In addition, microwave transitions between the Hg+ clock levels have been driven in the resonance trap and detected in the state selection trap.

Apparatus for magnetic and electrostatic confinement of plasma

DOEpatents

Rostoker, Norman; Binderbauer, Michl

2006-10-31

An apparatus and method for containing plasma and forming a Field Reversed Configuration (FRC) magnetic topology are described in which plasma ions are contained magnetically in stable, non-adiabatic orbits in the FRC. Further, the electrons are contained electrostatically in a deep energy well, created by tuning an externally applied magnetic field. The simultaneous electrostatic confinement of electrons and magnetic confinement of ions avoids anomalous transport and facilitates classical containment of both electrons and ions. In this configuration, ions and electrons may have adequate density and temperature so that upon collisions they are fused together by nuclear force, thus releasing fusion energy. Moreover, the fusion fuel plasmas that can be used with the present confinement system and method are not limited to neutronic fuels only, but also advantageously include advanced fuels.

Apparatus for magnetic and electrostatic confinement of plasma

DOEpatents

Rostoker, Norman; Binderbauer, Michl

2006-04-11

An apparatus and method for containing plasma and forming a Field Reversed Configuration (FRC) magnetic topology are described in which plasma ions are contained magnetically in stable, non-adiabatic orbits in the FRC. Further, the electrons are contained electrostatically in a deep energy well, created by tuning an externally applied magnetic field. The simultaneous electrostatic confinement of electrons and magnetic confinement of ions avoids anomalous transport and facilitates classical containment of both electrons and ions. In this configuration, ions and electrons may have adequate density and temperature so that upon collisions they are fused together by nuclear force, thus releasing fusion energy. Moreover, the fusion fuel plasmas that can be used with the present confinement system and method are not limited to neutronic fuels only, but also advantageously include advanced fuels.

Mini ion trap mass spectrometer

DOEpatents

Dietrich, Daniel D.; Keville, Robert F.

1995-01-01

An ion trap which operates in the regime between research ion traps which can detect ions with a mass resolution of better than 1:10.sup.9 and commercial mass spectrometers requiring 10.sup.4 ions with resolutions of a few hundred. The power consumption is kept to a minimum by the use of permanent magnets and a novel electron gun design. By Fourier analyzing the ion cyclotron resonance signals induced in the trap electrodes, a complete mass spectra in a single combined structure can be detected. An attribute of the ion trap mass spectrometer is that overall system size is drastically reduced due to combining a unique electron source and mass analyzer/detector in a single device. This enables portable low power mass spectrometers for the detection of environmental pollutants or illicit substances, as well as sensors for on board diagnostics to monitor engine performance or for active feedback in any process involving exhausting waste products.

Mini ion trap mass spectrometer

DOEpatents

Dietrich, D.D.; Keville, R.F.

1995-09-19

An ion trap is described which operates in the regime between research ion traps which can detect ions with a mass resolution of better than 1:10{sup 9} and commercial mass spectrometers requiring 10{sup 4} ions with resolutions of a few hundred. The power consumption is kept to a minimum by the use of permanent magnets and a novel electron gun design. By Fourier analyzing the ion cyclotron resonance signals induced in the trap electrodes, a complete mass spectra in a single combined structure can be detected. An attribute of the ion trap mass spectrometer is that overall system size is drastically reduced due to combining a unique electron source and mass analyzer/detector in a single device. This enables portable low power mass spectrometers for the detection of environmental pollutants or illicit substances, as well as sensors for on board diagnostics to monitor engine performance or for active feedback in any process involving exhausting waste products. 10 figs.

Electron source for a mini ion trap mass spectrometer

DOEpatents

Dietrich, Daniel D.; Keville, Robert F.

1995-01-01

An ion trap which operates in the regime between research ion traps which can detect ions with a mass resolution of better than 1:10.sup.9 and commercial mass spectrometers requiring 10.sup.4 ions with resolutions of a few hundred. The power consumption is kept to a minimum by the use of permanent magnets and a novel electron gun design. By Fourier analyzing the ion cyclotron resonance signals induced in the trap electrodes, a complete mass spectra in a single combined structure can be detected. An attribute of the ion trap mass spectrometer is that overall system size is drastically reduced due to combining a unique electron source and mass analyzer/detector in a single device. This enables portable low power mass spectrometers for the detection of environmental pollutants or illicit substances, as well as sensors for on board diagnostics to monitor engine performance or for active feedback in any process involving exhausting waste products.

Ion Temperature Measurements in an electron beam ion trap (EBIT)

NASA Astrophysics Data System (ADS)

Beiersdorfer, P.; Decaux, V.; Widmann, K.

1997-11-01

An electron beam ion trap consists of a Penning-type cylindrical trap traversed by a high-energy (<= 200 keV), high-density (Ne <= 10^13 cm-3) electron beam. Ions are trapped by the space charge potential of the electron beam, a static potential on the end electrodes, and a 3-T axial magnetic field [1]. The ions are heated by the electron beam and leave the trap once their kinetic energy suffices to overcome the potential barriers. Using high-resolution x-ray spectroscopy, we have made systematic measurements of the temperature of Ti^20+ and Cs^45+ ions in the trap [2]. The dependence of the ion temperature on operating parameters, such as trapping potential, beam current, and neutral gas pressure, will be presented. Temperatures as low as 15.4 ± 4.4 eV and as high as 2 keV were observed. *Work performed under the auspices of the U.S.D.o.E. by Lawrence Livermore National Laboratory under contract No. W-7405-ENG-48. [1] M. Levine et al., Phys. Scripta T22, 157 (1989). [2]P. Beiersdorfer et al., PRL 77, 5356 (1996); P. Beiersdorfer, in AIP Conf. Proc. No. 389, p. 121 (1997).

Parametric Excitation of Electrostatic Dust-Modes by Ion-Cyclotron Waves in a Dusty Plasma

NASA Astrophysics Data System (ADS)

Islam, M. K.; Salahuddin, M.; Ferdous, T.; Salimullah, M.

A large amplitude electrostatic ion-cyclotron wave propagating through a magnetized and collisional dusty plasma undergoes strong parametric instability off the low-frequency dust-modes. The presence of the dust-component has effect on the nonlinear coupling via the dust-modes. The ion-neutral collisions are seen to have significant effect on the damping and consequent overall growth of the parametric excitation process.

Influences of Mutations on the Electrostatic Binding Free Energies of Chloride Ions in Escherichia Coli ClC

PubMed Central

Yu, Tao; Wang, Xiao-Qing; Sang, Jian-Ping; Pan, Chun-Xu; Zou, Xian-Wu; Chen, Tsung-Yu; Zou, Xiaoqin

2012-01-01

Mutations in ClC channel proteins may cause serious functional changes and even diseases. The function of ClC proteins mainly manifests as Cl− transport, which is related to the binding free energies of chloride ions. Therefore, the influence of a mutation on ClC function can be studied by investigating the mutational effect on the binding free energies of chloride ions. The present study provides quantitative and systematic investigations on the influences of residue mutations on the electrostatic binding free energies in Escherichia coli ClC (EcClC) proteins, using all-atom molecular dynamics simulations. It was found that the change of the electrostatic binding free energy decreases linearly with the increase of the residue-chloride ion distance for a mutation. This work reveals how changes in the charge of a mutated residue and in the distance between the mutated residue and the binding site govern the variations in the electrostatic binding free energies, and therefore influence the transport of chloride ions and conduction in EcClC. This work would facilitate our understanding of the mutational effects on transport of chloride ions and functions of ClC proteins, and provide a guideline to estimate which residue mutations will have great influences on ClC functions. PMID:22612693

Ion traps fabricated in a CMOS foundry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mehta, K. K.; Ram, R. J.; Eltony, A. M.

2014-07-28

We demonstrate trapping in a surface-electrode ion trap fabricated in a 90-nm CMOS (complementary metal-oxide-semiconductor) foundry process utilizing the top metal layer of the process for the trap electrodes. The process includes doped active regions and metal interconnect layers, allowing for co-fabrication of standard CMOS circuitry as well as devices for optical control and measurement. With one of the interconnect layers defining a ground plane between the trap electrode layer and the p-type doped silicon substrate, ion loading is robust and trapping is stable. We measure a motional heating rate comparable to those seen in surface-electrode traps of similar size.more » This demonstration of scalable quantum computing hardware utilizing a commercial CMOS process opens the door to integration and co-fabrication of electronics and photonics for large-scale quantum processing in trapped-ion arrays.« less

Space-charge effects in Penning ion traps

NASA Astrophysics Data System (ADS)

Porobić, T.; Beck, M.; Breitenfeldt, M.; Couratin, C.; Finlay, P.; Knecht, A.; Fabian, X.; Friedag, P.; Fléchard, X.; Liénard, E.; Ban, G.; Zákoucký, D.; Soti, G.; Van Gorp, S.; Weinheimer, Ch.; Wursten, E.; Severijns, N.

2015-06-01

The influence of space-charge on ion cyclotron resonances and magnetron eigenfrequency in a gas-filled Penning ion trap has been investigated. Off-line measurements with K39+ using the cooling trap of the WITCH retardation spectrometer-based setup at ISOLDE/CERN were performed. Experimental ion cyclotron resonances were compared with ab initio Coulomb simulations and found to be in agreement. As an important systematic effect of the WITCH experiment, the magnetron eigenfrequency of the ion cloud was studied under increasing space-charge conditions. Finally, the helium buffer gas pressure in the Penning trap was determined by comparing experimental cooling rates with simulations.

Miniature Free-Space Electrostatic Ion Thrusters

NASA Technical Reports Server (NTRS)

Hartley, Frank T.; Stephens, James B.

2006-01-01

A miniature electrostatic ion thruster is proposed for maneuvering small spacecraft. In a thruster based on this concept, one or more propellant gases would be introduced into an ionizer based on the same principles as those of the device described in an earlier article, "Miniature Bipolar Electrostatic Ion Thruster". On the front side, positive ions leaving an ionizer element would be accelerated to high momentum by an electric field between the ionizer and an accelerator grid around the periphery of the concave laminate structure. On the front side, electrons leaving an ionizer element would be ejected into free space by a smaller accelerating field. The equality of the ion and electron currents would eliminate the need for an additional electron- or ion-emitting device to keep the spacecraft charge-neutral. In a thruster design consisting of multiple membrane ionizers in a thin laminate structure with a peripheral accelerator grid, the direction of thrust could then be controlled (without need for moving parts in the thruster) by regulating the supply of gas to specific ionizer.

Extended linear ion trap frequency standard apparatus

NASA Technical Reports Server (NTRS)

Prestage, John D. (Inventor)

1995-01-01

A linear ion trap for frequency standard applications is provided with a plurality of trapping rods equally spaced and applied quadruple rf voltages for radial confinement of atomic ions and biased level pins at each end for axial confinement of the ions. The trapping rods are divided into two linear ion trap regions by a gap in each rod in a common radial plane to provide dc discontinuity, thus dc isolating one region from the other. A first region for ion-loading and preparation fluorescence is biased with a dc voltage to transport ions into a second region for resonance frequency comparison with a local oscillator derived frequency while the second region is held at zero voltage. The dc bias voltage of the regions is reversed for transporting the ions back into the first region for fluorescence measurement. The dual mode cycle is repeated continuously for comparison and feedback control of the local oscillator derived frequency. Only the second region requires magnetic shielding for the resonance function which is sensitive to any ambient magnetic fields.

Adsorption of ions onto nanosolids dispersed in liquid crystals: Towards understanding the ion trapping effect in nanocolloids

NASA Astrophysics Data System (ADS)

Garbovskiy, Yuriy

2016-05-01

The ion capturing effect in liquid crystal nanocolloids was quantified by means of the ion trapping coefficient. The dependence of the ion trapping coefficient on the concentration of nano-dopants and their ionic purity was calculated for a variety of nanosolids dispersed in liquid crystals: carbon nanotubes, graphene nano-flakes, diamond nanoparticles, anatase nanoparticles, and ferroelectric nanoparticles. The proposed method perfectly fits existing experimental data and can be useful in the design of highly efficient ion capturing nanomaterials.

Ultrafast coherent excitation of a trapped ion qubit for fast gates and photon frequency qubits.

PubMed

Madsen, M J; Moehring, D L; Maunz, P; Kohn, R N; Duan, L-M; Monroe, C

2006-07-28

We demonstrate ultrafast coherent excitation of an atomic qubit stored in the hyperfine levels of a single trapped cadmium ion. Such ultrafast excitation is crucial for entangling networks of remotely located trapped ions through the interference of photon frequency qubits, and is also a key component for realizing ultrafast quantum gates between Coulomb-coupled ions.

The potential of combining ion trap/MS/MS and TOF/MS for identification of emerging contaminants

USGS Publications Warehouse

Ferrer, I.; Furlong, E.T.; Heine, C.E.; Thurman, E.M.

2002-01-01

The use of a method combining ion trap tandem mass spectrometry (MS/MS) and time of flight mass spectrometry (TOF/MS) for identification of emerging contaminates was discussed. The two tools together complemented each other in sensitivity, fragmentation and accurate mass determination. Liquid chromatography/electrospray ionization/ion-trap tandem mass spectrometry (LC/ESI/MS/MS), in positive ion mode of operation, was used to separate and identify specific compounds. Diagnostic fragment ions were obtained for a polyethyleneglycol(PEG) homolog by ion trap MS/MS, and fragments were measured by TOF/MS. It was observed that the combined method gave an exact mass measurement that differed from the calculated mass.

Transport implementation of the Bernstein-Vazirani algorithm with ion qubits

NASA Astrophysics Data System (ADS)

Fallek, S. D.; Herold, C. D.; McMahon, B. J.; Maller, K. M.; Brown, K. R.; Amini, J. M.

2016-08-01

Using trapped ion quantum bits in a scalable microfabricated surface trap, we perform the Bernstein-Vazirani algorithm. Our architecture takes advantage of the ion transport capabilities of such a trap. The algorithm is demonstrated using two- and three-ion chains. For three ions, an improvement is achieved compared to a classical system using the same number of oracle queries. For two ions and one query, we correctly determine an unknown bit string with probability 97.6(8)%. For three ions, we succeed with probability 80.9(3)%.

Spacelab energetic ion mass spectrometer

NASA Technical Reports Server (NTRS)

Whalen, B. A.; Mcdiarmid, I. B.; Burrows, J. R.; Sharp, R. D.; Johnson, R. G.; Shelley, E. G.

1980-01-01

Basic design criteria are given for an ion mass spectrometer for use in studying magnetospheric ion populations. The proposed instrument is composed of an electrostatic analyzer followed by a magnetic spectrometer and simultaneously measures the energy per unit and mass per unit charge of the ion species. An electromagnet is used for momentum analysis to extend the operational energy range over a much wider domain than is possible with the permanent magnets used in previous flights. The energetic ion source regions, ion energization mechanisms, field line tracing, coordinated investigations, and orbit considerations are discussed and operations of the momentum analyzer and of the electrostatic energy analyzer are examined.

A Monte-Carlo method which is not based on Markov chain algorithm, used to study electrostatic screening of ion potential

NASA Astrophysics Data System (ADS)

Šantić, Branko; Gracin, Davor

2017-12-01

A new simple Monte Carlo method is introduced for the study of electrostatic screening by surrounding ions. The proposed method is not based on the generally used Markov chain method for sample generation. Each sample is pristine and there is no correlation with other samples. As the main novelty, the pairs of ions are gradually added to a sample provided that the energy of each ion is within the boundaries determined by the temperature and the size of ions. The proposed method provides reliable results, as demonstrated by the screening of ion in plasma and in water.

First storage of ion beams in the Double Electrostatic Ion-Ring Experiment: DESIREE.

PubMed

Schmidt, H T; Thomas, R D; Gatchell, M; Rosén, S; Reinhed, P; Löfgren, P; Brännholm, L; Blom, M; Björkhage, M; Bäckström, E; Alexander, J D; Leontein, S; Hanstorp, D; Zettergren, H; Liljeby, L; Källberg, A; Simonsson, A; Hellberg, F; Mannervik, S; Larsson, M; Geppert, W D; Rensfelt, K G; Danared, H; Paál, A; Masuda, M; Halldén, P; Andler, G; Stockett, M H; Chen, T; Källersjö, G; Weimer, J; Hansen, K; Hartman, H; Cederquist, H

2013-05-01

We report on the first storage of ion beams in the Double ElectroStatic Ion Ring ExpEriment, DESIREE, at Stockholm University. We have produced beams of atomic carbon anions and small carbon anion molecules (C(n)(-), n = 1, 2, 3, 4) in a sputter ion source. The ion beams were accelerated to 10 keV kinetic energy and stored in an electrostatic ion storage ring enclosed in a vacuum chamber at 13 K. For 10 keV C2 (-) molecular anions we measure the residual-gas limited beam storage lifetime to be 448 s ± 18 s with two independent detector systems. Using the measured storage lifetimes we estimate that the residual gas pressure is in the 10(-14) mbar range. When high current ion beams are injected, the number of stored particles does not follow a single exponential decay law as would be expected for stored particles lost solely due to electron detachment in collision with the residual-gas. Instead, we observe a faster initial decay rate, which we ascribe to the effect of the space charge of the ion beam on the storage capacity.

Quadrupole ion traps and trap arrays: geometry, material, scale, performance.

PubMed

Ouyang, Z; Gao, L; Fico, M; Chappell, W J; Noll, R J; Cooks, R G

2007-01-01

Quadrupole ion traps are reviewed, emphasizing recent developments, especially the investigation of new geometries, guided by multiple particle simulations such as the ITSIM program. These geometries include linear ion traps (LITs) and the simplified rectilinear ion trap (RIT). Various methods of fabrication are described, including the use of rapid prototyping apparatus (RPA), in which 3D objects are generated through point-by-point laser polymerization. Fabrication in silicon using multilayer semi-conductor fabrication techniques has been used to construct arrays of micro-traps. The performance of instruments containing individual traps as well as arrays of traps of various sizes and geometries is reviewed. Two types of array are differentiated. In the first type, trap arrays constitute fully multiplexed mass spectrometers in which multiple samples are examined using multiple sources, analyzers and detectors, to achieve high throughput analysis. In the second, an array of individual traps acts collectively as a composite trap to increase trapping capacity and performance for a single sample. Much progress has been made in building miniaturized mass spectrometers; a specific example is a 10 kg hand-held tandem mass spectrometer based on the RIT mass analyzer. The performance of this instrument in air and water analysis, using membrane sampling, is described.

Equatorial heating and hemispheric decoupling effects on inner magnetospheric core plasma evolution

NASA Technical Reports Server (NTRS)

Lin, J.; Horwitz, J. L.; Wilson, G. R.; Brown, D. G.

1994-01-01

We have extended our previous semikinetic study of early stage plasmasphere refilling with perpendicular ion heating by removing the restriction that the northern and southern boundaries are identical and incorporating a generalized transport description for the electrons. This allows investigation of the effects of electron heating and a more realistic calculation of electric fields produced by ion and electron temperature anisotropies. The combination of perpendicular ion heating and parallel electron heating leads to an equatorial electrostatic potential peak, which tends to shield and decouple ion flows in the northern and southern hemispheres. Unequal ionospheric upflows in the northern and southern hemispheres lead to the development of distinctly asymmetric densities and other bulk parameters. At t = 5 hour after the initiation of refiling with different source densities (N(sub north) = 100 cu/cm, N(sub south) = 50 cu/cm), the maximum potential drops of the northern and southern hemispheres are 0.6 and 1.3 V, respectively. At this time the minimum ion densities are 11 and 7 cu/cm for the northern and southern hemispheres. DE 1 observations of asymmetric density profiles by Olsen may be consistent with these predictions. Termination of particle heating causes the reduction of equatorial potential and allows interhemispheric coupling. When the inflows from the ionospheres are reduced (as may occur after sunset), decreases in plasma density near the ionospheric regions are observed while the heated trapped ion population at the equator persists.

Electrostatic ion thruster optics calculations

NASA Technical Reports Server (NTRS)

Whealton, John H.; Kirkman, David A.; Raridon, R. J.

1992-01-01

Calculations have been performed which encompass both a self-consistent ion source extraction plasma sheath and the primary ion optics including sheath and electrode-induced aberrations. Particular attention is given to the effects of beam space charge, accelerator geometry, and properties of the downstream plasma sheath on the position of the electrostatic potential saddle point near the extractor electrode. The electron blocking potential blocking is described as a function of electrode thickness and secondary plasma processes.

The source of electrostatic fluctuations in the solar-wind

NASA Technical Reports Server (NTRS)

Lemons, D. S.; Asbridge, J. R.; Bame, S. J.; Feldman, W. C.; Gary, S. P.; Gosling, J. T.

1979-01-01

Solar wind electron and ion distribution functions measured simultaneously with or close to times of intense electrostatic fluctuations are subjected to a linear Vlasov stability analysis. Although all distributions tested were found to be stable, the analysis suggests that the ion beam instability is the most likely source of the fluctuations.

Determination of Ion Atmosphere Effects on the Nucleic Acid Electrostatic Potential and Ligand Association Using AH+·C Wobble Formation in Double-Stranded DNA

PubMed Central

2017-01-01

The high charge density of nucleic acids and resulting ion atmosphere profoundly influence the conformational landscape of RNA and DNA and their association with small molecules and proteins. Electrostatic theories have been applied to quantitatively model the electrostatic potential surrounding nucleic acids and the effects of the surrounding ion atmosphere, but experimental measures of the potential and tests of these models have often been complicated by conformational changes and multisite binding equilibria, among other factors. We sought a simple system to further test the basic predictions from electrostatics theory and to measure the energetic consequences of the nucleic acid electrostatic field. We turned to a DNA system developed by Bevilacqua and co-workers that involves a proton as a ligand whose binding is accompanied by formation of an internal AH+·C wobble pair [Siegfried, N. A., et al. Biochemistry, 2010, 49, 3225]. Consistent with predictions from polyelectrolyte models, we observed logarithmic dependences of proton affinity versus salt concentration of −0.96 ± 0.03 and −0.52 ± 0.01 with monovalent and divalent cations, respectively, and these results help clarify prior results that appeared to conflict with these fundamental models. Strikingly, quantitation of the ion atmosphere content indicates that divalent cations are preferentially lost over monovalent cations upon A·C protonation, providing experimental indication of the preferential localization of more highly charged cations to the inner shell of the ion atmosphere. The internal AH+·C wobble system further allowed us to parse energetic contributions and extract estimates for the electrostatic potential at the position of protonation. The results give a potential near the DNA surface at 20 mM Mg2+ that is much less substantial than at 20 mM K+ (−120 mV vs −210 mV). These values and difference are similar to predictions from theory, and the potential is substantially reduced at higher salt, also as predicted; however, even at 1 M K+ the potential remains substantial, counter to common assumptions. The A·C protonation module allows extraction of new properties of the ion atmosphere and provides an electrostatic meter that will allow local electrostatic potential and energetics to be measured within nucleic acids and their complexes with proteins. PMID:28489947

Characterization of a Compact Cryogenic Package Approach to Ion Trap Quantum Comuting

NASA Astrophysics Data System (ADS)

Spivey, Robert; Vrijsen, Geert; Ahn, Byeong-Hyeon; Hudek, Kai; Crain, Stephen; van Rynbach, Andre; Rachel, Noek; Kim, Jungsang

One challenge for the expansion of trapped ion systems to a large scale is the lack of repeatable integration technology to realize compact and stable operating environment. In this work, we present a novel ion trapping environment where conventional ultra-high vacuum (UHV) chambers are replaced with a sealed ceramic package operating in a cryogenic environment. A microfabricated surface ion trap mounted on a 100-pin ceramic pin grid array (CPGA) package is placed in a UHV environment. A titanium lid with windows for optical access is then attached to the CPGA via an indium seal which maintains the UHV conditions for the ion trap. The trap package assembly is operated at cryogenic temperatures (5K) in order to freeze out most of the residual background gas. Activated charcoal is used to pump remaining helium and hydrogen molecules. Metallic Yb ablated using a Q-switched Nd:YAG laser at 1,064 nm is used as the atomic source. A compact radio frequency resonant circuit is used to create the RF potential for trapping. A low output impedance amplifier drives a superconducting inductor of value 2 uH in series with the trap capacitance in order to produce 200V at 26 MHz with low heating at 5K. We present the experimental progress towards trapping ions in this compact cryogenic setup.

Formation of a field reversed configuration for magnetic and electrostatic confinement of plasma

DOEpatents

Rostoker, Norman; Binderbauer, Michl

2003-12-16

A system and method for containing plasma and forming a Field Reversed Configuration (FRC) magnetic topology are described in which plasma ions are contained magnetically in stable, non-adiabatic orbits in the FRC. Further, the electrons are contained electrostatically in a deep energy well, created by tuning an externally applied magnetic field. The simultaneous electrostatic confinement of electrons and magnetic confinement of ions avoids anomalous transport and facilitates classical containment of both electrons and ions. In this configuration, ions and electrons may have adequate density and temperature so that upon collisions they are fused together by nuclear force, thus releasing fusion energy. Moreover, the fusion fuel plasmas that can be used with the present confinement system and method are not limited to neutronic fuels only, but also advantageously include advanced fuels.

Formation of a field reversed configuration for magnetic and electrostatic confinement of plasma

DOEpatents

Rostoker, Norman; Binderbauer, Michl; Qerushi, Artan; Tahsiri, Hooshang

2007-02-20

A system and method for containing plasma and forming a Field Reversed Configuration (FRC) magnetic topology are described in which plasma ions are contained magnetically in stable, non-adiabatic orbits in the FRC. Further, the electrons are contained electrostatically in a deep energy well, created by tuning an externally applied magnetic field. The simultaneous electrostatic confinement of electrons and magnetic confinement of ions avoids anomalous transport and facilitates classical containment of both electrons and ions. In this configuration, ions and electrons may have adequate density and temperature so that upon collisions they are fused together by nuclear force, thus releasing fusion energy. Moreover, the fusion fuel plasmas that can be used with the present confinement system and method are not limited to neutronic fuels only, but also advantageously include advanced fuels.

Formation of a field reversed configuration for magnetic and electrostatic confinement of plasma

DOEpatents

Rostoker, Norman; Binderbauer, Michl; Qerushi, Artan; Tahsiri, Hooshang

2006-02-07

A system and method for containing plasma and forming a Field Reversed Configuration (FRC) magnetic topology are described in which plasma ions are contained magnetically in stable, non-adiabatic orbits in the FRC. Further, the electrons are contained electrostatically in a deep energy well, created by tuning an externally applied magnetic field. The simultaneous electrostatic confinement of electrons and magnetic confinement of ions avoids anomalous transport and facilitates classical containment of both electrons and ions. In this configuration, ions and electrons may have adequate density and temperature so that upon collisions they are fused together by nuclear force, thus releasing fusion energy. Moreover, the fusion fuel plasmas that can be used with the present confinement system and method are not limited to neutronic fuels only, but also advantageously include advanced fuels.

Quantum dynamics of charge state in silicon field evaporation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Silaeva, Elena P.; Uchida, Kazuki; Watanabe, Kazuyuki, E-mail: kazuyuki@rs.kagu.tus.ac.jp

2016-08-15

The charge state of an ion field-evaporating from a silicon-atom cluster is analyzed using time-dependent density functional theory coupled to molecular dynamics. The final charge state of the ion is shown to increase gradually with increasing external electrostatic field in agreement with the average charge state of silicon ions detected experimentally. When field evaporation is triggered by laser-induced electronic excitations the charge state also increases with increasing intensity of the laser pulse. At the evaporation threshold, the charge state of the evaporating ion does not depend on the electrostatic field due to the strong contribution of laser excitations to themore » ionization process both at low and high laser energies. A neutral silicon atom escaping the cluster due to its high initial kinetic energy is shown to be eventually ionized by external electrostatic field.« less

New experimental measurements of electron clouds in ion beams with large tune depression

DOE Office of Scientific and Technical Information (OSTI.GOV)

Molvik, A W; Covo, M K; Cohen, R H

We study electron clouds in high perveance beams (K = 8E-4) with a large tune depression of 0.2 (defined as the ratio of a single particle oscillation response to the applied focusing fields, with and without space charge). These 1 MeV, 180 mA, K+ beams have a beam potential of +2 kV when electron clouds are minimized. Simulation results are discussed in a companion paper [J-L. Vay, this Conference]. We have developed the first diagnostics that quantitatively measure the accumulation of electrons in a beam [1]. This, together with measurements of electron sources, will enable the electron particle balance tomore » be measured, and electron-trapping efficiencies determined. We, along with colleagues from GSI and CERN, have also measured the scaling of gas desorption with beam energy and dE/dx [2]. Experiments where the heavy-ion beam is transported with solenoid magnetic fields, rather than with quadrupole magnetic or electrostatic fields, are being initiated. We will discuss initial results from experiments using electrode sets (in the middle and at the ends of magnets) to either expel or to trap electrons within the magnets. We observe electron oscillations in the last quadrupole magnet when we flood the beam with electrons from an end wall. These oscillations, of order 10 MHz, are observed to grow from the center of the magnet while drifting upstream against the beam, in good agreement with simulations.« less

Magnetic Compensation for Second-Order Doppler Shift in LITS

NASA Technical Reports Server (NTRS)

Burt, Eric; Tjoelker, Robert

2008-01-01

The uncertainty in the frequency of a linear-ion-trap frequency standard (LITS) can be reduced substantially by use of a very small magnetic inhomogeneity tailored to compensate for the residual second-order Doppler shift. An effect associated with the relativistic time dilatation, one cause of the second-order Doppler shift, is ion motion that is attributable to the trapping radio-frequency (RF)electromagnetic field used to trap ions. The second-order Doppler shift is reduced by using a multi-pole trap; however it is still the largest source of systematic frequency shift in the latest generation of LITSs, which are among the most stable clocks in the world. The present compensation scheme reduces the frequency instability of the affected LITS to about a tenth of its previous value. The basic principles of prior generation LITSs were discussed in several prior NASA Tech Briefs articles. Below are recapitulated only those items of basic information necessary to place the present development in context. A LITS includes a microwave local oscillator, the frequency of which is stabilized by comparison with the frequency of the ground state hyperfine transition of 199Hg+ ions. The comparison involves a combination of optical and microwave excitation and interrogation of the ions in a linear ion trap in the presence of a nominally uniform magnetic field. In the current version of the LITS, there are two connected traps (see figure): (1) a quadrupole trap wherein the optical excitation and measurement take place and (2) a 12-pole trap (denoted the resonance trap), wherein the microwave interrogation takes place. The ions are initially loaded into the quadrupole trap and are thereafter shuttled between the two traps. Shuttling ions into the resonance trap allows sensitive microwave interrogation to take place well away from loading interference. The axial magnetic field for the resonance trap is generated by an electric current in a finely wound wire coil surrounded by magnetic shields. In the quadrupole and 12-pole traps, the potentials are produced by RF voltages applied to even numbers (4 and 12, respectively) of parallel rods equally spaced around a circle. The polarity of the voltage on each rod is opposite that of the voltage on the adjacent rod. As a result, the amplitude of the RF trapping field is zero along the centerline and increases, with radius, to a maximum value near the rods.

Quantum Information Experiments with Trapped Ions at NIST

NASA Astrophysics Data System (ADS)

Wilson, Andrew

2015-03-01

We present an overview of recent trapped-ion quantum information experiments at NIST. Advancing beyond few-qubit ``proof-of-principle'' experiments to the many-qubit systems needed for practical quantum simulation and information processing, without compromising on the performance demonstrated with small systems, remains a major challenge. One approach to scalable hardware development is surface-electrode traps. Micro-fabricated planar traps can have a number of useful features, including flexible electrode geometries, integrated microwave delivery, and spatio-temporal tuning of potentials for ion transport and spin-spin interactions. In this talk we report on a number of on-going investigations with surface traps. Experiments feature a multi-zone trap with closely spaced ions in a triangular arrangement (a first step towards 2D arrays of ions with tunable spin-spin interactions), a scheme for smooth transport through a junction in a 2D structure based on switchable RF potentials, and a micro-fabricated photo-detector integrated into a trap. We also give a progress report on our latest efforts to improve the fidelity of both optical and microwave 2-qubit gates. This work was supported by IARPA, ONR and the NIST Quantum Information Program. The 3-ion and switchable-RF-junction traps were developed in collaboration with Sandia National Laboratory.

Experimental system design for the integration of trapped-ion and superconducting qubit systems

NASA Astrophysics Data System (ADS)

De Motte, D.; Grounds, A. R.; Rehák, M.; Rodriguez Blanco, A.; Lekitsch, B.; Giri, G. S.; Neilinger, P.; Oelsner, G.; Il'ichev, E.; Grajcar, M.; Hensinger, W. K.

2016-12-01

We present a design for the experimental integration of ion trapping and superconducting qubit systems as a step towards the realization of a quantum hybrid system. The scheme addresses two key difficulties in realizing such a system: a combined microfabricated ion trap and superconducting qubit architecture, and the experimental infrastructure to facilitate both technologies. Developing upon work by Kielpinski et al. (Phys Rev Lett 108(13):130504, 2012. doi: 10.1103/PhysRevLett.108.130504), we describe the design, simulation and fabrication process for a microfabricated ion trap capable of coupling an ion to a superconducting microwave LC circuit with a coupling strength in the tens of kHz. We also describe existing difficulties in combining the experimental infrastructure of an ion trapping set-up into a dilution refrigerator with superconducting qubits and present solutions that can be immediately implemented using current technology.

Frequency-scanning MALDI linear ion trap mass spectrometer for large biomolecular ion detection.

PubMed

Lu, I-Chung; Lin, Jung Lee; Lai, Szu-Hsueh; Chen, Chung-Hsuan

2011-11-01

This study presents the first report on the development of a matrix-assisted laser desorption ionization (MALDI) linear ion trap mass spectrometer for large biomolecular ion detection by frequency scan. We designed, installed, and tested this radio frequency (RF) scan linear ion trap mass spectrometer and its associated electronics to dramatically extend the mass region to be detected. The RF circuit can be adjusted from 300 to 10 kHz with a set of operation amplifiers. To trap the ions produced by MALDI, a high pressure of helium buffer gas was employed to quench extra kinetic energy of the heavy ions produced by MALDI. The successful detection of the singly charged secretory immunoglobulin A ions indicates that the detectable mass-to-charge ratio (m/z) of this system can reach ~385 000 or beyond.

A versatile MOF-based trap for heavy metal ion capture and dispersion.

PubMed

Peng, Yaguang; Huang, Hongliang; Zhang, Yuxi; Kang, Chufan; Chen, Shuangming; Song, Li; Liu, Dahuan; Zhong, Chongli

2018-01-15

Current technologies for removing heavy metal ions are typically metal ion specific. Herein we report the development of a broad-spectrum heavy metal ion trap by incorporation of ethylenediaminetetraacetic acid into a robust metal-organic framework. The capture experiments for a total of 22 heavy metal ions, covering hard, soft, and borderline Lewis metal ions, show that the trap is very effective, with removal efficiencies of >99% for single-component adsorption, multi-component adsorption, or in breakthrough processes. The material can also serve as a host for metal ion loading with arbitrary selections of metal ion amounts/types with a controllable uptake ratio to prepare well-dispersed single or multiple metal catalysts. This is supported by the excellent performance of the prepared Pd 2+ -loaded composite toward the Suzuki coupling reaction. This work proposes a versatile heavy metal ion trap that may find applications in the fields of separation and catalysis.

Electrostatic ion instabilities in the presence of parallel currents and transverse electric fields

NASA Technical Reports Server (NTRS)

Ganguli, G.; Palmadesso, P. J.

1988-01-01

The electrostatic ion instabilities are studied for oblique propagation in the presence of magnetic field-aligned currents and transverse localized electric fields in a weakly collisional plasma. The presence of transverse electric fields result in mode excitation for magnetic field aligned current values that are otherwise stable. The electron collisions enhance the growth while ion collisions have a damping effect. These results are discussed in the context of observations of low frequency ion modes in the auroral ionosphere by radar and rocket experiments.

Stripline fast faraday cup for measuring GHz structure of ion beams

DOEpatents

Bogaty, John M.

1992-01-01

The Stripline Fast Faraday Cup is a device which is used to quantitatively and qualitatively measure gigahertz time structure characteristics of ion beams with energies up to at least 30 Mev per nucleon. A stripline geometry is employed in conjunction with an electrostatic screen and a Faraday cup to provide for analysis of the structural characteristics of an ion beam. The stripline geometry allows for a large reduction in the size of the instrument while the electrostatic screen permits measurements of the properties associated with low speed ion beams.

Electron source for a mini ion trap mass spectrometer

DOEpatents

Dietrich, D.D.; Keville, R.F.

1995-12-19

An ion trap is described which operates in the regime between research ion traps which can detect ions with a mass resolution of better than 1:10{sup 9} and commercial mass spectrometers requiring 10{sup 4} ions with resolutions of a few hundred. The power consumption is kept to a minimum by the use of permanent magnets and a novel electron gun design. By Fourier analyzing the ion cyclotron resonance signals induced in the trap electrodes, a complete mass spectra in a single combined structure can be detected. An attribute of the ion trap mass spectrometer is that overall system size is drastically reduced due to combining a unique electron source and mass analyzer/detector in a single device. This enables portable low power mass spectrometers for the detection of environmental pollutants or illicit substances, as well as sensors for on board diagnostics to monitor engine performance or for active feedback in any process involving exhausting waste products. 10 figs.

Ionic Structure at Dielectric Interfaces

NASA Astrophysics Data System (ADS)

Jing, Yufei

The behavior of ions in liquids confined between macromolecules determines the outcome of many nanoscale assembly processes in synthetic and biological materials such as colloidal dispersions, emulsions, hydrogels, DNA, cell membranes, and proteins. Theoretically, the macromolecule-liquid boundary is often modeled as a dielectric interface and an important quantity of interest is the ionic structure in a liquid confined between two such interfaces. The knowledge gleaned from the study of ionic structure in such models can be useful in several industrial applications, such as biosensors, lithium-ion batteries double-layer supercapacitors for energy storage and seawater desalination. Electrostatics plays a critical role in the development of such functional materials. Many of the functions of these materials, result from charge and composition heterogeneities. There are great challenges in solving electrostatics problems in heterogeneous media with arbitrary shapes because electrostatic interactions remains unknown but depend on the particular density of charge distributions. Charged molecules in heterogeneous media affect the media's dielectric response and hence the interaction between the charges is unknown since it depends on the media and on the geometrical properties of the interfaces. To determine the properties of heterogeneous systems including crucial effects neglected in classical mean field models such as the hard core of the ions, the dielectric mismatch and interfaces with arbitrary shapes. The effect of hard core interactions accounts properly for short range interactions and the effect of local dielectric heterogeneities in the presence of ions and/or charged molecules for long-range interactions are both analyzed via an energy variational principle that enables to update charges and the medium's response in the same simulation time step. In particular, we compute the ionic structure in a model system of electrolyte confined by two planar dielectric interfaces using molecular dynamics(MD) simulations and compared it with liquid state theory result. We explore the effects of high electrolyte concentrations, multivalent ions, and dielectric contrasts on the ionic distributions. We observe the presence of non-monotonous ionic density profiles leading to structure deformation in the fluid which is attributed to the competition between electrostatic and steric (entropic) interactions. We find that thermal forces that arise from symmetry breaking at the interfaces can have a profound effect on the ionic structure and can oftentimes overwhelm the influence of dielectric discontinuity. The combined effect of ionic correlations and inhomogeneous dielectric permittivity significantly changes the character of effective interaction between two interfaces. We show that, in concentrated electrolytes with confinement, it is imperative to take into account the finite-size of the ions as well as proper description of electrostatic interactions in heterogeneous media, which is not fully fulfilled by Poisson-Boltzmann based approaches. The effect of electric field at interface between two immiscible electrolyte solutions is studied as well. The classical Poisson-Boltzmann theory has been widely used to describe the corresponding ionic distribution, even though it neglects the polarization and ion correlations typical of these charged systems. Using Monte Carlo simulations, we provide an enhanced description of an oil-water interface in the presence of an electric field without needing any adjustable parameter, including realistic ionic sizes, ion correlations, and image charges. Our data agree with experimental measurements of excess surface tension for a wide range of electrolyte concentrations of LiCl and TBATPB (tetrabutylammonium-tetraphenylborate), contrasting with the result of the classical non-linear Poisson-Boltzmann theory. More importantly, we show that the size-asymmetry between small Li+ and large Cl- ions can significantly increase the electric field near the liquid interface, or can even reverse it locally, at high salt concentrations in the aqueous phase. These observations suggest a novel trapping/release mechanism of charged nanoparticles at oil-water interfaces in the vicinity of the point of zero charge. In addition, we study the effects of size asymmetry and charge asymmetry on ion distribution at a dielectric interface using coarse-grained MD based on an energy variational principle. The goal is to explore charge amplification with exact consideration of surface polarization. We find that both size asymmetry and charge asymmetry lead to charge separation at the interfaces. In addition, charge separation is enhanced by interface polarization. We are currently extending the research to charged interfaces that has broad applications such as batteries and supercapacitors for energy storage.

Novel control modes to improve the performance of rectilinear ion trap mass spectrometer with dual pressure chambers

NASA Astrophysics Data System (ADS)

Huo, Xinming; Tang, Fei; Zhang, Xiaohua; Chen, Jin; Zhang, Yan; Guo, Cheng'an; Wang, Xiaohao

2016-10-01

The rectilinear ion trap (RIT) has gradually become one of the preferred mass analyzers for portable mass spectrometers because of its simple configuration. In order to enhance the performance, including sensitivity, quantitation capability, throughput, and resolution, a novel RIT mass spectrometer with dual pressure chambers was designed and characterized. The studied system constituted a quadrupole linear ion trap (QLIT) in the first chamber and a RIT in the second chamber. Two control modes are hereby proposed: Storage Quadrupole Linear Ion Trap-Rectilinear Ion Trap (SQLIT-RIT) mode, in which the QLIT was used at high pressure for ion storage and isolation, and the RIT was used for analysis; and Analysis Quadrupole Linear Ion Trap-Rectilinear Ion Trap (AQLIT-RIT) mode, in which the QLIT was used for ion storage and cooling. Subsequently, synchronous scanning and analysis were carried out by QLIT and RIT. In SQLIT-RIT mode, signal intensity was improved by a factor of 30; the limit of quantitation was reduced more than tenfold to 50 ng mL-1, and an optimal duty cycle of 96.4% was achieved. In AQLIT-RIT mode, the number of ions coexisting in the RIT was reduced, which weakened the space-charge effect and reduced the mass shift. Furthermore, the mass resolution was enhanced by a factor of 3. The results indicate that the novel control modes achieve satisfactory performance without adding any system complexity, which provides a viable pathway to guarantee good analytical performance in miniaturization of the mass spectrometer.

TBI server: a web server for predicting ion effects in RNA folding.

PubMed

Zhu, Yuhong; He, Zhaojian; Chen, Shi-Jie

2015-01-01

Metal ions play a critical role in the stabilization of RNA structures. Therefore, accurate prediction of the ion effects in RNA folding can have a far-reaching impact on our understanding of RNA structure and function. Multivalent ions, especially Mg²⁺, are essential for RNA tertiary structure formation. These ions can possibly become strongly correlated in the close vicinity of RNA surface. Most of the currently available software packages, which have widespread success in predicting ion effects in biomolecular systems, however, do not explicitly account for the ion correlation effect. Therefore, it is important to develop a software package/web server for the prediction of ion electrostatics in RNA folding by including ion correlation effects. The TBI web server http://rna.physics.missouri.edu/tbi_index.html provides predictions for the total electrostatic free energy, the different free energy components, and the mean number and the most probable distributions of the bound ions. A novel feature of the TBI server is its ability to account for ion correlation and ion distribution fluctuation effects. By accounting for the ion correlation and fluctuation effects, the TBI server is a unique online tool for computing ion-mediated electrostatic properties for given RNA structures. The results can provide important data for in-depth analysis for ion effects in RNA folding including the ion-dependence of folding stability, ion uptake in the folding process, and the interplay between the different energetic components.

Quantum information processing with trapped ions

NASA Astrophysics Data System (ADS)

Gaebler, John

2013-03-01

Trapped ions are one promising architecture for scalable quantum information processing. Ion qubits are held in multizone traps created from segmented arrays of electrodes and transported between trap zones using time varying electric potentials applied to the electrodes. Quantum information is stored in the ions' internal hyperfine states and quantum gates to manipulate the internal states and create entanglement are performed with laser beams and microwaves. Recently we have made progress in speeding up the ion transport and cooling processes that were the limiting tasks for the operation speed in previous experiments. We are also exploring improved two-qubit gates and new methods for creating ion entanglement. This work was supported by IARPA, ARO contract No. EAO139840, ONR and the NIST Quantum Information Program

A cooler Penning trap for the TITAN mass measurement facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chowdhury, U.; Kootte, B.; Good, M.

The TITAN facility at TRIUMF makes use of highly charged ions, charge-bred in an electron beam ion trap, to carry out accurate mass measurements on radioactive isotopes. We report on our progress to develop a cooler Penning trap, CPET, which aims at reducing the energy spread of the ions to ≈ 1 eV/charge prior to injection into the mass measurement trap. In off-line mode, we can now trap electron plasmas for minutes, and we observe the damping of the m = 1 diocotron plasma mode within ≈ 2 s.

Galactic heavy-ion shielding using electrostatic fields

NASA Technical Reports Server (NTRS)

Townsend, L. W.

1984-01-01

The shielding of spacecraft against galactic heavy ions, particularly high-energy Fe(56) nuclei, by electrostatic fields is analyzed for an arrangement of spherical concentric shells. Vacuum breakdown considerations are found to limit the minimum radii of the spheres to over 100 m. This limitation makes it impractical to use the fields for shielding small spacecraft. The voltages necessary to repel these Fe(56) nuclei exceed present electrostatic generating capabilities by over 2 orders of magnitude and render the concept useless as an alternative to traditional bulk-material shielding methods.

The Poisson-Helmholtz-Boltzmann model.

PubMed

Bohinc, K; Shrestha, A; May, S

2011-10-01

We present a mean-field model of a one-component electrolyte solution where the mobile ions interact not only via Coulomb interactions but also through a repulsive non-electrostatic Yukawa potential. Our choice of the Yukawa potential represents a simple model for solvent-mediated interactions between ions. We employ a local formulation of the mean-field free energy through the use of two auxiliary potentials, an electrostatic and a non-electrostatic potential. Functional minimization of the mean-field free energy leads to two coupled local differential equations, the Poisson-Boltzmann equation and the Helmholtz-Boltzmann equation. Their boundary conditions account for the sources of both the electrostatic and non-electrostatic interactions on the surface of all macroions that reside in the solution. We analyze a specific example, two like-charged planar surfaces with their mobile counterions forming the electrolyte solution. For this system we calculate the pressure between the two surfaces, and we analyze its dependence on the strength of the Yukawa potential and on the non-electrostatic interactions of the mobile ions with the planar macroion surfaces. In addition, we demonstrate that our mean-field model is consistent with the contact theorem, and we outline its generalization to arbitrary interaction potentials through the use of a Laplace transformation. © EDP Sciences / Società Italiana di Fisica / Springer-Verlag 2011

Experimental Characterization of Secular Frequency Scanning in Ion Trap Mass Spectrometers

NASA Astrophysics Data System (ADS)

Snyder, Dalton T.; Pulliam, Christopher J.; Wiley, Joshua S.; Duncan, Jason; Cooks, R. Graham

2016-07-01

Secular frequency scanning is implemented and characterized using both a benchtop linear ion trap and a miniature rectilinear ion trap mass spectrometer. Separation of tetraalkylammonium ions and those from a mass calibration mixture and from a pesticide mixture is demonstrated with peak widths approaching unit resolution for optimized conditions using the benchtop ion trap. The effects on the spectra of ion trap operating parameters, including waveform amplitude, scan direction, scan rate, and pressure are explored, and peaks at black holes corresponding to nonlinear (higher-order field) resonance points are investigated. Reverse frequency sweeps (increasing mass) on the Mini 12 are shown to result in significantly higher ion ejection efficiency and superior resolution than forward frequency sweeps that decrement mass. This result is accounted for by the asymmetry in ion energy absorption profiles as a function of AC frequency and the shift in ion secular frequency at higher amplitudes in the trap due to higher order fields. We also found that use of higher AC amplitudes in forward frequency sweeps biases ions toward ejection at points of higher order parametric resonance, despite using only dipolar excitation. Higher AC amplitudes also increase peak width and decrease sensitivity in both forward and reverse frequency sweeps. Higher sensitivity and resolution were obtained at higher trap pressures in the secular frequency scan, in contrast to conventional resonance ejection scans, which showed the opposite trend in resolution on the Mini 12. Mass range is shown to be naturally extended in secular frequency scanning when ejecting ions by sweeping the AC waveform through low frequencies, a method which is similar, but arguably superior, to the more usual method of mass range extension using low q resonance ejection.

Experimental Characterization of Secular Frequency Scanning in Ion Trap Mass Spectrometers.

PubMed

Snyder, Dalton T; Pulliam, Christopher J; Wiley, Joshua S; Duncan, Jason; Cooks, R Graham

2016-07-01

Secular frequency scanning is implemented and characterized using both a benchtop linear ion trap and a miniature rectilinear ion trap mass spectrometer. Separation of tetraalkylammonium ions and those from a mass calibration mixture and from a pesticide mixture is demonstrated with peak widths approaching unit resolution for optimized conditions using the benchtop ion trap. The effects on the spectra of ion trap operating parameters, including waveform amplitude, scan direction, scan rate, and pressure are explored, and peaks at black holes corresponding to nonlinear (higher-order field) resonance points are investigated. Reverse frequency sweeps (increasing mass) on the Mini 12 are shown to result in significantly higher ion ejection efficiency and superior resolution than forward frequency sweeps that decrement mass. This result is accounted for by the asymmetry in ion energy absorption profiles as a function of AC frequency and the shift in ion secular frequency at higher amplitudes in the trap due to higher order fields. We also found that use of higher AC amplitudes in forward frequency sweeps biases ions toward ejection at points of higher order parametric resonance, despite using only dipolar excitation. Higher AC amplitudes also increase peak width and decrease sensitivity in both forward and reverse frequency sweeps. Higher sensitivity and resolution were obtained at higher trap pressures in the secular frequency scan, in contrast to conventional resonance ejection scans, which showed the opposite trend in resolution on the Mini 12. Mass range is shown to be naturally extended in secular frequency scanning when ejecting ions by sweeping the AC waveform through low frequencies, a method which is similar, but arguably superior, to the more usual method of mass range extension using low q resonance ejection. Graphical Abstract ᅟ.

Phase transitions in local equation-of-state approximation and anomalies of spatial charge profiles in non-uniform plasma

NASA Astrophysics Data System (ADS)

Chigvintsev, A. Yu; Zorina, I. G.; Noginova, L. Yu; Iosilevskiy, I. L.

2018-01-01

Impressive appearance of discontinuities in equilibrium spatial charge profiles in non-uniform Coulomb systems is under discussions in wide number of thermoelectrostatics problems. Such discontinuities are considered as peculiar micro-level manifestation of phase transitions and intrinsic macro-level non-ideality effects in local equation of state (EOS), which should be used for description of non-ideal ionic subsystem in frames of local-density (or “pseudofluid”, or “jellium” etc) approximation. Such discontinuities were discussed already by the authors for electronic subsystems. Special emphasis is made in present paper on the mentioned above non-ideality effects in non-uniform ionic subsystems, such as micro-ions profile within screening “cloud” around macro-ion in complex (dusty, colloid etc) plasmas, equilibrium charge profile in ionic traps or (and) in the neighborhood vicinity of “charged wall” etc). Multiphase EOS for simplified ionic model of classical charged hard spheres on uniformly compressible electrostatic compensating background was constructed and several illustrative examples of discussed discontinuous ionic profiles were calculated.

Unique capabilities of AC frequency scanning and its implementation on a Mars Organic Molecule Analyzer linear ion trap.

PubMed

Snyder, Dalton T; Kaplan, Desmond A; Danell, Ryan M; van Amerom, Friso H W; Pinnick, Veronica T; Brinckerhoff, William B; Mahaffy, Paul R; Cooks, R Graham

2017-06-21

A limitation of conventional quadrupole ion trap scan modes which use rf amplitude control for mass scanning is that, in order to detect a subset of an ion population, the rest of the ion population must also be interrogated. That is, ions cannot be detected out of order; they must be detected in order of either increasing or decreasing mass-to-charge (m/z). However, an ion trap operated in the ac frequency scan mode, where the rf amplitude is kept constant and instead the ac frequency is used for mass-selective operations, has no such limitation because any variation in the ac frequency affects only the subset of ions whose secular frequencies match the perturbation frequency. Hence, an ion trap operated in the ac frequency scan mode can perform any arbitrary mass scan, as well as a sequence of scans, using a single ion injection; we demonstrate both capabilities here. Combining these two capabilities, we demonstrate the acquisition of a full mass spectrum, a product ion spectrum, and a second generation product ion spectrum using a single ion injection event. We further demonstrate a "segmented scan" in which different mass ranges are interrogated at different rf amplitudes in order to improve resolution over a portion of the mass range, and a "periodic scan" in which ions are continuously introduced into the ion trap to achieve a nearly 100% duty cycle. These unique scan modes, along with other characteristics of ac frequency scanning, are particularly appropriate for miniature ion trap mass spectrometers. Hence, implementation of ac frequency scanning on a prototype of the Mars Organic Molecule Analyzer mass spectrometer is also described.

Spontaneous Mass and Charge Losses from Single Multi-Megadalton Ions Studied by Charge Detection Mass Spectrometry

NASA Astrophysics Data System (ADS)

Keifer, David Z.; Alexander, Andrew W.; Jarrold, Martin F.

2017-03-01

Spontaneous mass and charge losses from individual multi-megadalton ions have been observed with charge detection mass spectrometry (CDMS) by trapping single hepatitis B virus (HBV) capsids for 3 s. Gradual increases in the oscillation frequency of single ions in the ion trap are attributed mainly to mass loss (probably solvent, water, and/or salt). The total mass lost during the 3 s trapping period peaks at around 20 kDa for 4 MDa HBV T = 4 capsids. Discrete frequency drops punctuate the gradual increases in the oscillation frequencies. The drops are attributed to a sudden loss of charge. In most cases a single positive charge is lost along with some mass (on average around 1000 Da). Charge loss occurs for over 40% of the trapped ions. It usually occurs near the beginning of the trapping event, and it occurs preferentially in regions of the trap with strong electric fields, indicating that external electric fields promote charge loss. This process may contribute to the decrease in m/ z resolution that often occurs with megadalton ions.

Hg(+) Frequency Standards

NASA Technical Reports Server (NTRS)

Prestage, John D.; Tjoelker, Robert L.; Maleki, Lute

2000-01-01

In this paper we review the development of Hg(+) microwave frequency standards for use in high reliability and continuous operation applications. In recent work we have demonstrated short-term frequency stability of 3 x 10(exp -14)/nu(sub tau) when a cryogenic oscillator of stability 2-3 x 10(exp 15) was used a the local oscillator. The trapped ion frequency standard employs a Hg-202 discharge lamp to optically pump the trapped Hg(+)-199 clock ions and a helium buffer gas to cool the ions to near room temperature. We describe a small Hg(+) ion trap based frequency standard with an extended linear ion trap (LITE) architecture which separates the optical state selection region from the clock resonance region. This separation allows the use of novel trap configurations in the resonance region since no optical pumping is carried out there. A method for measuring the size of an ion cloud inside a linear trap with a 12-rod trap is currently being investigated. At approx. 10(exp -12), the 2nd order Doppler shift for trapped mercury ion frequency standards is one of the largest frequency offsets and its measurement to the 1% level would represent an advance in insuring the very long-term stability of these standards to the 10(exp -14) or better level. Finally, we describe atomic clock comparison experiments that can probe for a time variation of the fine structure constant, alpha = e(exp 2)/2(pi)hc, at the level of 10(exp -20)/year as predicted in some Grand Unified String Theories.

RF-Trapped Chip Scale Helium Ion Pump (RFT-CHIP)

DTIC Science & Technology

2016-04-06

14. ABSTRACT A miniaturized (~1 cc) magnet -less RF electron trap for a helium ion pump is studied, addressing challenges associated with active...pump, ion pump, electron trap, magnet -less, MEMS, radiofrequency 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT 18. NUMBER OF PAGES 19a...scale ion pumps. The Penning cell structure consists of three electrodes (an anode and two cathodes) and a magnet . Planar titanium cathodes are

Modular Universal Scalable Ion-trap Quantum Computer

DTIC Science & Technology

2016-06-02

SECURITY CLASSIFICATION OF: The main goal of the original MUSIQC proposal was to construct and demonstrate a modular and universally- expandable ion...Distribution Unlimited UU UU UU UU 02-06-2016 1-Aug-2010 31-Jan-2016 Final Report: Modular Universal Scalable Ion-trap Quantum Computer The views...P.O. Box 12211 Research Triangle Park, NC 27709-2211 Ion trap quantum computation, scalable modular architectures REPORT DOCUMENTATION PAGE 11

Two dimensional nonplanar evolution of electrostatic shock waves in pair-ion plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Masood, W.; Rizvi, H.

2012-01-15

Electrostatic waves in a two dimensional nonplanar geometry are studied in an unmagnetized, dissipative pair-ion plasma in the presence of weak transverse perturbations. The dissipation in the system is taken into account by incorporating the kinematic viscosity of both positive and negative ions in plasmas. The nonplanar Kadomtsev-Petviashvili-Burgers (KPB) as well as the Burgers Kadomtsev-Petviashvili (Burgers KP) equations are derived using the small amplitude expansion method and the range of applicability of both the equations are discussed. The system under consideration is observed to admit compressive rarefactive shocks. The present study may have relevance to understand the formation of twomore » dimensional nonplanar electrostatic shocks in laboratory plasmas.« less

Micromachined patch-clamp apparatus

DOEpatents

Okandan, Murat

2012-12-04

A micromachined patch-clamp apparatus is disclosed for holding one or more cells and providing electrical, chemical, or mechanical stimulation to the cells during analysis with the patch-clamp technique for studying ion channels in cell membranes. The apparatus formed on a silicon substrate utilizes a lower chamber formed from silicon nitride using surface micromachining and an upper chamber formed from a molded polymer material. An opening in a common wall between the chambers is used to trap and hold a cell for analysis using the patch-clamp technique with sensing electrodes on each side of the cell. Some embodiments of the present invention utilize one or more electrostatic actuators formed on the substrate to provide mechanical stimulation to the cell being analyzed, or to provide information about mechanical movement of the cell in response to electrical or chemical stimulation.

Electron capture dissociation in a branched radio-frequency ion trap.

PubMed

Baba, Takashi; Campbell, J Larry; Le Blanc, J C Yves; Hager, James W; Thomson, Bruce A

2015-01-06

We have developed a high-throughput electron capture dissociation (ECD) device coupled to a quadrupole time-of-flight mass spectrometer using novel branched radio frequency ion trap architecture. With this device, a low-energy electron beam can be injected orthogonally into the analytical ion beam with independent control of both the ion and electron beams. While ions and electrons can interact in a "flow-through" mode, we observed a large enhancement in ECD efficiency by introducing a short ion trapping period at the region of ion and electron beam intersection. This simultaneous trapping mode still provides up to five ECD spectra per second while operating in an information-dependent acquisition workflow. Coupled to liquid chromatography (LC), this LC-ECD workflow provides good sequence coverage for both trypsin and Lys C digests of bovine serum albumin, providing ECD spectra for doubly charged precursor ions with very good efficiency.

On the Relativistic Correction of Particles Trajectory in Tandem Type Electrostatic Accelerator

NASA Astrophysics Data System (ADS)

Minárik, Stanislav

2015-08-01

A constant potential is applied to the acceleration of the ion-beam in the tandem type electrostatic accelerator. However, not just one voltage is applied, but instead a number of applications can be made in succession by means of the tandem arrangement of high voltage tubes. This number of voltage applications, which is the number of so-called "stages" of a tandem accelerator, may be two, three, or four, depending on the chosen design. Electrostatic field with approximately constant intensity acts on ions in any stage. In general, non-relativistic dynamics is used for the description of the ion transport in tandem accelerator. Energies of accelerated ions are too low and relativistic effects cannot be commonly observed by standard experimental technique. Estimation of possible relativistic correction of ion trajectories is therefore only a matter of calculation. In this note, we briefly present such calculation. Our aim is to show how using the relativistic dynamics modifies the particles trajectory in tandem type accelerator and what parameters determine this modification.

Two dimensional electrostatic shock waves in relativistic electron positron ion plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Masood, W.; Rizvi, H.

2010-05-15

Ion-acoustic shock waves (IASWs) are studied in an unmagnetized plasma consisting of electrons, positrons and hot ions. In this regard, Kadomtsev-Petviashvili-Burgers (KPB) equation is derived using the small amplitude perturbation expansion method. The dependence of the IASWs on various plasma parameters is numerically investigated. It is observed that ratio of ion to electron temperature, kinematic viscosity, positron concentration, and the relativistic ion streaming velocity affect the structure of the IASW. Limiting case of the KPB equation is also discussed. Stability of KPB equation is also presented. The present investigation may have relevance in the study of electrostatic shock waves inmore » relativistic electron-positron-ion plasmas.« less

Reducing detrimental electrostatic effects in Casimir-force measurements and Casimir-force-based microdevices

NASA Astrophysics Data System (ADS)

Xu, Jun; Klimchitskaya, G. L.; Mostepanenko, V. M.; Mohideen, U.

2018-03-01

It is well known that residual electrostatic forces create significant difficulties in precise measurements of the Casimir force and the wide use of Casimir-operated microdevices. We experimentally demonstrate that, with the help of Ar-ion cleaning of the surfaces, it is possible to make electrostatic effects negligibly small compared to the Casimir interaction. Our experimental setup consists of a dynamic atomic force microscope supplemented with an Ar-ion gun and argon reservoir. The residual potential difference between the Au-coated surfaces of a sphere and those of a plate was measured both before and after in situ Ar-ion cleaning. It is shown that this cleaning decreases the magnitude of the residual potential by up to an order of magnitude and makes it almost independent of the separation. The gradient of the Casimir force was measured using ordinary samples subjected to Ar-ion cleaning. The obtained results are shown to be in good agreement both with previous precision measurements using specially selected samples and with theoretical predictions of the Lifshitz theory. The conclusion is made that the suggested method of in situ Ar-ion cleaning is effective in reducing the electrostatic effects and therefore is a great resource for experiments on measuring the Casimir interaction and for Casimir-operated microdevices.

Preliminary Tests of a Paul ion Trap as an Ion Source

NASA Astrophysics Data System (ADS)

Sadat Kiai, S. M.; Zirak, A. R.; Elahi, M.; Adlparvar, S.; Mortazavi, B. N.; Safarien, A.; Farhangi, S.; Sheibani, S.; Alhooie, S.; Khalaj, M. M. A.; Dabirzadeh, A. A.; Ruzbehani, M.; Zahedi, F.

2010-10-01

The paper reports on the design and construction of a Paul ion trap as an ion source by using an impact electron ionization technique. Ions are produced in the trap and confined for the specific time which is then extracted and detected by a Faraday cup. Especial electronic configurations are employed between the end caps, ring electrodes, electron gun and a negative voltage for the detector. This configuration allows a constant low level of pure ion source between the pulsed confined ion sources. The present experimental results are based on the production and confinement of Argon ions with good stability and repeatability, but in principle, the technique can be used for various Argon like ions.

Microfabricated Microwave-Integrated Surface Ion Trap

NASA Astrophysics Data System (ADS)

Revelle, Melissa C.; Blain, Matthew G.; Haltli, Raymond A.; Hollowell, Andrew E.; Nordquist, Christopher D.; Maunz, Peter

2017-04-01

Quantum information processing holds the key to solving computational problems that are intractable with classical computers. Trapped ions are a physical realization of a quantum information system in which qubits are encoded in hyperfine energy states. Coupling the qubit states to ion motion, as needed for two-qubit gates, is typically accomplished using Raman laser beams. Alternatively, this coupling can be achieved with strong microwave gradient fields. While microwave radiation is easier to control than a laser, it is challenging to precisely engineer the radiated microwave field. Taking advantage of Sandia's microfabrication techniques, we created a surface ion trap with integrated microwave electrodes with sub-wavelength dimensions. This multi-layered device permits co-location of the microwave antennae and the ion trap electrodes to create localized microwave gradient fields and necessary trapping fields. Here, we characterize the trap design and present simulated microwave performance with progress towards experimental results. This research was funded, in part, by the Office of the Director of National Intelligence (ODNI), Intelligence Advanced Research Projects Activity (IARPA).

Solar wind pickup of ionized Venus exosphere atoms

NASA Technical Reports Server (NTRS)

Curtis, S. A.

1981-01-01

Previous calculations of electrostatic and electromagnetic growth rates for plasma instabilities have neglected the thermal spread of the distribution function of the planetary ions. We consider the effects of finite temperatures for exospheric ions borne in the solar wind. Specifically, growth rates are calculated for electromagnetic instabilities in the low-frequency case for Alfven waves and the intermediate frequency case for whistlers. Also, electrostatic growth rates are calculated for the intermediate frequency regime. From these growth rates, estimates are derived for the pickup times of the planetary ions. The electromagnetic instabilities are shown to produce the most rapid pickup. In the situation where the angle between the local Venus magnetic field and the plasma flow direction is small, the pickup times for both electromagnetic and electrostatic instabilities become very long. A possible consequence of this effect is to produce regions of enhanced planetary ion density in favorable Venus magnetic field-solar wind flow geometries.

Ion Transport and Acceleration at Dipolarization Fronts: High-Resolution MHD/Test-Particle Simulations

NASA Astrophysics Data System (ADS)

Ukhorskiy, A. Y.; Sorathia, K.; Merkin, V. G.; Sitnov, M. I.; Mitchell, D. G.; Wiltberger, M. J.; Lyon, J.

2017-12-01

Much of plasma heating and transport from the magnetotail into the inner magnetosphere occurs in the form of mesoscale discrete injections associated with sharp dipolarizations of magnetic field (dipolarization fronts). In this study we investigate the mechanisms of ion acceleration at dipolarization fronts in a high-resolution global magnetospheric MHD model (LFM). We use large-scale three-dimensional test-particle simulations (CHIMP) to address the following science questions: 1) what are the characteristic scales of dipolarization regions that can stably trap ions? 2) what role does the trapping play in ion transport and acceleration? 3) how does it depend on particle energy and distance from Earth? 4) to what extent ion acceleration is adiabatic? High-resolution LFM was run using idealized solar wind conditions with fixed nominal values of density and velocity and a southward IMF component of -5 nT. To simulate ion interaction with dipolarization fronts, a large ensemble of test particles distributed in energy, pitch-angle, and gyrophase was initialized inside one of the LFM dipolarization channels in the magnetotail. Full Lorentz ion trajectories were then computed over the course of the front inward propagation from the distance of 17 to 6 Earth radii. A large fraction of ions with different initial energies stayed in phase with the front over the entire distance. The effect of magnetic trapping at different energies was elucidated with a correlation of the ion guiding center and the ExB drift velocities. The role of trapping in ion energization was quantified by comparing the partial pressure of ions that exhibit trapping to the pressure of all trapped ions.

Coupling of electrostatic ion cyclotron and ion acoustic waves in the solar wind

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sreeraj, T., E-mail: sreerajt13@iigs.iigm.res.in; Singh, S. V., E-mail: satyavir@iigs.iigm.res.in; Lakhina, G. S., E-mail: gslakhina@gmail.com

2016-08-15

The coupling of electrostatic ion cyclotron and ion acoustic waves is examined in three component magnetized plasma consisting of electrons, protons, and alpha particles. In the theoretical model relevant to solar wind plasma, electrons are assumed to be superthermal with kappa distribution and protons as well as alpha particles follow the fluid dynamical equations. A general linear dispersion relation is derived for such a plasma system which is analyzed both analytically and numerically. For parallel propagation, electrostatic ion cyclotron (proton and helium cyclotron) and ion acoustic (slow and fast) modes are decoupled. For oblique propagation, coupling between the cyclotron andmore » acoustic modes occurs. Furthermore, when the angle of propagation is increased, the separation between acoustic and cyclotron modes increases which is an indication of weaker coupling at large angle of propagation. For perpendicular propagation, only cyclotron modes are observed. The effect of various parameters such as number density and temperature of alpha particles and superthermality on dispersion characteristics is examined in details. The coupling between various modes occurs for small values of wavenumber.« less

Imaging MS Methodology for More Chemical Information in Less Data Acquisition Time Utilizing a Hybrid Linear Ion Trap-Orbitrap Mass Spectrometer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Perdian, D. C.; Lee, Young Jin

2010-11-15

A novel mass spectrometric imaging method is developed to reduce the data acquisition time and provide rich chemical information using a hybrid linear ion trap-orbitrap mass spectrometer. In this method, the linear ion trap and orbitrap are used in tandem to reduce the acquisition time by incorporating multiple linear ion trap scans during an orbitrap scan utilizing a spiral raster step plate movement. The data acquisition time was decreased by 43-49% in the current experiment compared to that of orbitrap-only scans; however, 75% or more time could be saved for higher mass resolution and with a higher repetition rate laser.more » Using this approach, a high spatial resolution of 10 {micro}m was maintained at ion trap imaging, while orbitrap spectra were acquired at a lower spatial resolution, 20-40 {micro}m, all with far less data acquisition time. Furthermore, various MS imaging methods were developed by interspersing MS/MS and MSn ion trap scans during orbitrap scans to provide more analytical information on the sample. This method was applied to differentiate and localize structural isomers of several flavonol glycosides from an Arabidopsis flower petal in which MS/MS, MSn, ion trap, and orbitrap images were all acquired in a single data acquisition.« less

Study of In-Trap Ion Clouds by Ion Trajectory Simulations.

PubMed

Zhou, Xiaoyu; Liu, Xinwei; Cao, Wenbo; Wang, Xiao; Li, Ming; Qiao, Haoxue; Ouyang, Zheng

2018-02-01

Gaussian distribution has been utilized to describe the global number density distribution of ion cloud in the Paul trap, which is known as the thermal equilibrium theory and widely used in theoretical modeling of ion clouds in the ion traps. Using ion trajectory simulations, however, the ion clouds can now also be treated as a dynamic ion flow field and the location-dependent features could now be characterized. This study was carried out to better understand the in-trap ion cloud properties, such as the local particle velocity and temperature. The local ion number densities were found to be heterogeneously distributed in terms of mean and distribution width; the velocity and temperature of the ion flow varied with pressure depending on the flow type of the neutral molecules; and the "quasi-static" equilibrium status can only be achieved after a certain number of collisions, for which the time period is pressure-dependent. This work provides new insights of the ion clouds that are globally stable but subjected to local rf heating and collisional cooling. Graphical Abstract ᅟ.

Cigarette Smoke Cadmium Breakthrough from Traditional Filters: Implications for Exposure

PubMed Central

Pappas, R. Steven; Fresquez, Mark R.; Watson, Clifford H.

2015-01-01

Cadmium, a carcinogenic metal, is highly toxic to renal, skeletal, nervous, respiratory, and cardiovascular systems. Accurate and precise quantification of mainstream smoke cadmium levels in cigarette smoke is important because of exposure concerns. The two most common trapping techniques for collecting mainstream tobacco smoke particulate for analysis are glass fiber filters and electrostatic precipitators. We observed that a significant portion of total cadmium passed through standard glass fiber filters that are used to trap particulate matter. We therefore developed platinum traps to collect the cadmium that passed through the filters and tested a variety of cigarettes with different physical parameters for quantities of cadmium that passed though the filters. We found less than 1% cadmium passed through electrostatic precipitators. In contrast, cadmium that passed through 92 mm glass fiber filters on a rotary smoking machine was significantly higher, ranging from 3.5% to 22.9% of total smoke cadmium deliveries. Cadmium passed through 44 mm filters typically used on linear smoking machines to an even greater degree, ranging from 13.6% to 30.4% of the total smoke cadmium deliveries. Differences in the cadmium that passed through from the glass fiber filters and electrostatic precipitator could be explained in part if cadmium resides in the smaller mainstream smoke aerosol particle sizes. Differences in particle size distribution could have toxicological implications and could help explain the pulmonary and cardiovascular cadmium uptake in smokers. PMID:25313385

General Unknown Screening by Ion Trap LC/MS/MS

DTIC Science & Technology

2010-04-01

Subtitle 5 . Report Date April 2010 General Unknown Screening by Ion Trap LC/MS/MS 6 . Performing Organization Code 7. Author(s) 8... 5 Table 1: Analytical Data for Each of the...359 Compounds in the LC/MS/MS Library . . . . . . . . . . . 6 1 General Unknown ScreeninG by ion Trap lc/MS/MS INTrOduCTION The Federal Aviation

Electrostatic turbulence in the earth's central plasma sheet produced by multiple-ring ion distributions

NASA Technical Reports Server (NTRS)

Huba, J. D.; Chen, J.; Anderson, R. R.

1992-01-01

Attention is given to a mechanism to generate a broad spectrum of electrostatic turbulence in the quiet time central plasma sheet (CPS) plasma. It is shown theoretically that multiple-ring ion distributions can generate short-wavelength (less than about 1), electrostatic turbulence with frequencies less than about kVj, where Vj is the velocity of the jth ring. On the basis of a set of parameters from measurements made in the CPS, it is found that electrostatic turbulence can be generated with wavenumbers in the range of 0.02 and 1.0, with real frequencies in the range of 0 and 10, and with linear growth rates greater than 0.01 over a broad range of angles relative to the magnetic field (5-90 deg). These theoretical results are compared with wave data from ISEE 1 using an ion distribution function exhibiting multiple-ring structures observed at the same time. The theoretical results in the linear regime are found to be consistent with the wave data.

Simulation of electrostatic turbulence in the plasma sheet boundary layer with electron currents and bean-shaped ion beams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nishikawa, K.; Frank, L.A.; Huang, C.Y.

Plasma data from ISEE 1 show the presence of electron currents as well as energetic ion beams in the plasma sheet boundary layer. Broadband electrostatic noise and low-frequency electromagnetic bursts are detected in the plasma sheet boundary layer, especially in the presence of strong ion flows, currents, and steep spacial gradients in the fluxes of few-keV electrons and ions. Particle simulations have been performed to investigate electrostatic turbulence driven by a cold electron beam and/or ion beams with a bean-shaped velocity distribution. The simulation results show that the counterstreaming ion beams as well as the counterstreaming of the cold electronmore » beam and the ion beam excite ion acoustic waves with the Doppler-shifted real frequency ..omega..approx. = +- k/sub parallel/(c/sub s/-V/sub i//sub //sub parallel/). However, the effect of the bean-shaped ion velocity distributions reduces the growth rates of ion acoustic instability. The simulation results also show that the slowing down of the ion beam is larger at the larger perpendicular velocity. The wave spectra of the electric fields at some points for simulations show turbulence generated by growing waves. The frequency of these spectra ranges from ..cap omega../sub i/ to ..omega../sub p//sub e/, which is in qualitative agreement with the satellite data. copyright American Geophysical Union 1988« less

Characterization of compounds by time-of-flight measurement utilizing random fast ions

DOEpatents

Conzemius, R.J.

1989-04-04

An apparatus is described for characterizing the mass of sample and daughter particles, comprising a source for providing sample ions; a fragmentation region wherein a fraction of the sample ions may fragment to produce daughter ion particles; an electrostatic field region held at a voltage level sufficient to effect ion-neutral separation and ion-ion separation of fragments from the same sample ion and to separate ions of different kinetic energy; a detector system for measuring the relative arrival times of particles; and processing means operatively connected to the detector system to receive and store the relative arrival times and operable to compare the arrival times with times detected at the detector when the electrostatic field region is held at a different voltage level and to thereafter characterize the particles. Sample and daughter particles are characterized with respect to mass and other characteristics by detecting at a particle detector the relative time of arrival for fragments of a sample ion at two different electrostatic voltage levels. The two sets of particle arrival times are used in conjunction with the known altered voltage levels to mathematically characterize the sample and daughter fragments. In an alternative embodiment the present invention may be used as a detector for a conventional mass spectrometer. In this embodiment, conventional mass spectrometry analysis is enhanced due to further mass resolving of the detected ions. 8 figs.

Characterization of compounds by time-of-flight measurement utilizing random fast ions

DOEpatents

Conzemius, Robert J.

1989-01-01

An apparatus for characterizing the mass of sample and daughter particles, comprising a source for providing sample ions; a fragmentation region wherein a fraction of the sample ions may fragment to produce daughter ion particles; an electrostatic field region held at a voltage level sufficient to effect ion-neutral separation and ion-ion separation of fragments from the same sample ion and to separate ions of different kinetic energy; a detector system for measuring the relative arrival times of particles; and processing means operatively connected to the detector system to receive and store the relative arrival times and operable to compare the arrival times with times detected at the detector when the electrostatic field region is held at a different voltage level and to thereafter characterize the particles. Sample and daughter particles are characterized with respect to mass and other characteristics by detecting at a particle detector the relative time of arrival for fragments of a sample ion at two different electrostatic voltage levels. The two sets of particle arrival times are used in conjunction with the known altered voltage levels to mathematically characterize the sample and daughter fragments. In an alternative embodiment the present invention may be used as a detector for a conventional mass spectrometer. In this embodiment, conventional mass spectrometry analysis is enhanced due to further mass resolving of the detected ions.

Electrostatic potential of B-DNA: effect of interionic correlations.

PubMed Central

Gavryushov, S; Zielenkiewicz, P

1998-01-01

Modified Poisson-Boltzmann (MPB) equations have been numerically solved to study ionic distributions and mean electrostatic potentials around a macromolecule of arbitrarily complex shape and charge distribution. Results for DNA are compared with those obtained by classical Poisson-Boltzmann (PB) calculations. The comparisons were made for 1:1 and 2:1 electrolytes at ionic strengths up to 1 M. It is found that ion-image charge interactions and interionic correlations, which are neglected by the PB equation, have relatively weak effects on the electrostatic potential at charged groups of the DNA. The PB equation predicts errors in the long-range electrostatic part of the free energy that are only approximately 1.5 kJ/mol per nucleotide even in the case of an asymmetrical electrolyte. In contrast, the spatial correlations between ions drastically affect the electrostatic potential at significant separations from the macromolecule leading to a clearly predicted effect of charge overneutralization. PMID:9826596

Electron beam ion source and electron beam ion trap (invited).

PubMed

Becker, Reinard; Kester, Oliver

2010-02-01

The electron beam ion source (EBIS) and its trap variant [electron beam ion trap (EBIT)] celebrated their 40th and 20th anniversary, respectively, at the EBIS/T Symposium 2007 in Heidelberg. These technologically challenging sources of highly charged ions have seen a broad development in many countries over the last decades. In contrast to most other ion sources the recipe of improvement was not "sorcery" but a clear understanding of the physical laws and obeying the technological constraints. This review will report important achievements of the past as well as promising developments in the future.

Stable Trapping of Multielectron Helium Bubbles in a Paul Trap

NASA Astrophysics Data System (ADS)

Joseph, E. M.; Vadakkumbatt, V.; Pal, A.; Ghosh, A.

2017-06-01

In a recent experiment, we have used a linear Paul trap to store and study multielectron bubbles (MEBs) in liquid helium. MEBs have a charge-to-mass ratio (between 10^{-4} and 10^{-2} C/kg) which is several orders of magnitude smaller than ions (between 10^6 and 10^8 C/kg) studied in traditional ion traps. In addition, MEBs experience significant drag force while moving through the liquid. As a result, the experimental parameters for stable trapping of MEBs, such as magnitude and frequency of the applied electric fields, are very different from those used in typical ion trap experiments. The purpose of this paper is to model the motion of MEBs inside a linear Paul trap in liquid helium, determine the range of working parameters of the trap, and compare the results with experiments.

Branches of electrostatic turbulence inside solitary plasma structures in the auroral ionosphere

DOE Office of Scientific and Technical Information (OSTI.GOV)

Golovchanskaya, Irina V.; Kozelov, Boris V.; Chernyshov, Alexander A.

2014-08-15

The excitation of electrostatic turbulence inside space-observed solitary structures is a central topic of this exposition. Three representative solitary structures observed in the topside auroral ionosphere as large-amplitude nonlinear signatures in the electric field and magnetic-field-aligned current on the transverse scales of ∼10{sup 2}–10{sup 3} m are evaluated by the theories of electrostatic wave generation in inhomogeneous background configurations. A quantitative analysis shows that the structures are, in general, effective in destabilizing the inhomogeneous energy-density-driven (IEDD) waves, as well as of the ion acoustic waves modified by a shear in the parallel drift of ions. It is demonstrated that the dominatingmore » branch of the electrostatic turbulence is determined by the interplay of various driving sources inside a particular solitary structure. The sources do not generally act in unison, so that their common effect may be inhibiting for excitation of electrostatic waves of a certain type. In the presence of large magnetic-field-aligned current, which is not correlated to the inhomogeneous electric field inside the structure, the ion-acoustic branch becomes dominating. In other cases, the IEDD instability is more central.« less

From transistor to trapped-ion computers for quantum chemistry.

PubMed

Yung, M-H; Casanova, J; Mezzacapo, A; McClean, J; Lamata, L; Aspuru-Guzik, A; Solano, E

2014-01-07

Over the last few decades, quantum chemistry has progressed through the development of computational methods based on modern digital computers. However, these methods can hardly fulfill the exponentially-growing resource requirements when applied to large quantum systems. As pointed out by Feynman, this restriction is intrinsic to all computational models based on classical physics. Recently, the rapid advancement of trapped-ion technologies has opened new possibilities for quantum control and quantum simulations. Here, we present an efficient toolkit that exploits both the internal and motional degrees of freedom of trapped ions for solving problems in quantum chemistry, including molecular electronic structure, molecular dynamics, and vibronic coupling. We focus on applications that go beyond the capacity of classical computers, but may be realizable on state-of-the-art trapped-ion systems. These results allow us to envision a new paradigm of quantum chemistry that shifts from the current transistor to a near-future trapped-ion-based technology.

From transistor to trapped-ion computers for quantum chemistry

PubMed Central

Yung, M.-H.; Casanova, J.; Mezzacapo, A.; McClean, J.; Lamata, L.; Aspuru-Guzik, A.; Solano, E.

2014-01-01

Over the last few decades, quantum chemistry has progressed through the development of computational methods based on modern digital computers. However, these methods can hardly fulfill the exponentially-growing resource requirements when applied to large quantum systems. As pointed out by Feynman, this restriction is intrinsic to all computational models based on classical physics. Recently, the rapid advancement of trapped-ion technologies has opened new possibilities for quantum control and quantum simulations. Here, we present an efficient toolkit that exploits both the internal and motional degrees of freedom of trapped ions for solving problems in quantum chemistry, including molecular electronic structure, molecular dynamics, and vibronic coupling. We focus on applications that go beyond the capacity of classical computers, but may be realizable on state-of-the-art trapped-ion systems. These results allow us to envision a new paradigm of quantum chemistry that shifts from the current transistor to a near-future trapped-ion-based technology. PMID:24395054

Final Report - Advanced Ion Trap Mass Spectrometry Program - Oak Ridge National Laboratory - Sandia National Laboratory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Whitten, W.B.

This report covers the three main projects that collectively comprised the Advanced Ion Trap Mass Spectrometry Program. Chapter 1 describes the direct interrogation of individual particles by laser desorption within the ion trap mass spectrometer analyzer. The goals were (1) to develop an ''intelligent trigger'' capable of distinguishing particles of biological origin from those of nonbiological origin in the background and interferent particles and (2) to explore the capability for individual particle identification. Direct interrogation of particles by laser ablation and ion trap mass spectrometry was shown to have good promise for discriminating between particles of biological origin and thosemore » of nonbiological origin, although detailed protocols and operating conditions were not worked out. A library of more than 20,000 spectra of various types of biological particles has been assembled. Methods based on multivariate analysis and on neural networks were used to discriminate between particles of biological origin and those of nonbiological origin. It was possible to discriminate between at least some species of bacteria if mass spectra of several hundred similar particles were obtained. Chapter 2 addresses the development of a new ion trap mass analyzer geometry that offers the potential for a significant increase in ion storage capacity for a given set of analyzer operating conditions. This geometry may lead to the development of smaller, lower-power field-portable ion trap mass spectrometers while retaining laboratory-scale analytical performance. A novel ion trap mass spectrometer based on toroidal ion storage geometry has been developed. The analyzer geometry is based on the edge rotation of a quadrupolar ion trap cross section into the shape of a torus. Initial performance of this device was poor, however, due to the significant contribution of nonlinear fields introduced by the rotation of the symmetric ion-trapping geometry. These nonlinear resonances contributed to poor mass resolution and sensitivity and to erratic ion ejection behavior. To correct for these nonlinear effects, the geometry of the toroid ion trap analyzer has been modified to create an asymmetric torus, as first suggested by computer simulations that predicted significantly improved performance and unit mass resolution for this geometry. A reduced-sized version (one-fifth scale) has been fabricated but was not tested within the scope of this project. Chapter 3 describes groundbreaking progress toward the use of ion-ion chemistry to control the charge state of ions formed by the electrospray ionization process, which in turn enables precision analysis of whole proteins. In addition, this technique may offer the unique possibility of a priori identification of unknown biological material when employed with existing proteomics and genomic databases. Ion-ion chemistry within the ion trap was used to reduce the ions in highly charged states to states of +1 and +2 charges. Reduction in charge greatly simplifies identification of molecular weights of fragments from large biological molecules. This technique enables the analysis of whole proteins as biomarkers for the detection and identification of all three classes of biological weapons (bacteria, toxins, and viruses). In addition to methods development, tests were carried out with samples of tap water, local creek water, and soil (local red clay) spiked with melittin (bee venom), cholera toxin, and virus MS2. All three analytes were identified in tap water and soil; however, all three were problematic for detection in creek water at concentrations of 1 nM. More development of methods is needed.« less

Electron Gyro-Harmonic Effects on Ionospheric Stimulated Brillouin Scatter

DTIC Science & Technology

2014-08-21

27709-2211 Brillouin, SBS, emission lines, pump frequency stepping, cyclotron , EIC, airglow, upper hybrid REPORT DOCUMENTATION PAGE 11. SPONSOR...direction and the background magnetic field vector, the excited electrostatic wave could be either ion acoustic (IA) or electrostatic ion cyclotron (EIC...A. Hedberg, B. Lundborg, P. Stubbe, H. Kopka, and M. T. Rietveld (1989), Stimulated electromagnetic emission near electron cyclotron harmonics in

Dynamics and control of fast ion crystal splitting in segmented Paul traps (Open Access, Publisher’s Version)

DTIC Science & Technology

2014-07-09

operations, in addition to laser - or microwave-driven logic gates. Essential shuttling operations are splitting and merging of linear ion crystals. It is...from stray charges, laser induced charging of the trap [19], trap geometry imperfections or residual ponderomotive forces along the trap axis. The...transfer expressed as the mean phonon number Δ ω¯ = n E / f . We distinguish several regimes of laser –ion interaction: (i) if the vibrational

Numerical Methods of Computational Electromagnetics for Complex Inhomogeneous Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cai, Wei

Understanding electromagnetic phenomena is the key in many scientific investigation and engineering designs such as solar cell designs, studying biological ion channels for diseases, and creating clean fusion energies, among other things. The objectives of the project are to develop high order numerical methods to simulate evanescent electromagnetic waves occurring in plasmon solar cells and biological ion-channels, where local field enhancement within random media in the former and long range electrostatic interactions in the latter are of major challenges for accurate and efficient numerical computations. We have accomplished these objectives by developing high order numerical methods for solving Maxwell equationsmore » such as high order finite element basis for discontinuous Galerkin methods, well-conditioned Nedelec edge element method, divergence free finite element basis for MHD, and fast integral equation methods for layered media. These methods can be used to model the complex local field enhancement in plasmon solar cells. On the other hand, to treat long range electrostatic interaction in ion channels, we have developed image charge based method for a hybrid model in combining atomistic electrostatics and continuum Poisson-Boltzmann electrostatics. Such a hybrid model will speed up the molecular dynamics simulation of transport in biological ion-channels.« less

Deuterium trapping in tungsten

NASA Astrophysics Data System (ADS)

Poon, Michael

Tungsten is one of the primary material candidates being investigated for use in the first-wall of a magnetic confinement fusion reactor. An ion accelerator was used to simulate the type of ion interaction that may occur at a plasma-facing material. Thermal desorption spectroscopy (TDS) was the primary tool used to analyze the effects of the irradiation. Secondary ion mass spectroscopy (SIMS) was used to determine the distribution of trapped D in the tungsten specimen. The tritium migration analysis program (TMAP) was used to simulate thermal desorption profiles from the D depth distributions. Fitting of the simulated thermal desorption profiles with the measured TDS results provided values of the D trap energies. Deuterium trapping in single crystal tungsten was studied as a function of the incident ion fluence, ion flux, irradiation temperature, irradiation history, and surface impurity levels during irradiation. The results show that deuterium was trapped at vacancies and voids. Two deuterium atoms could be trapped at a tungsten vacancy, with trapping energies of 1.4 eV and 1.2 eV for the first and second D atoms, respectively. In a tungsten void, D is trapped as atoms adsorbed on the inner walls of the void with a trap energy of 2.1 eV, or as D2 molecules inside the void with a trap energy of 1.2 eV. Deuterium trapping in polycrystalline tungsten was also studied as a function of the incident fluence, irradiation temperature, and irradiation history. Deuterium trapping in polycrystalline tungsten also occurs primarily at vacancies and voids with the same trap energies as in single crystal tungsten; however, the presence of grain boundaries promotes the formation of large surface blisters with high fluence irradiations at 500 K. In general, D trapping is greater in polycrystalline tungsten than in single crystal tungsten. To simulate mixed materials comprising of carbon (C) and tungsten, tungsten specimens were pre-irradiated with carbon ions prior to D irradiation. Deuterium trapping could be characterized by three regimes: (i) enhanced D retention in a graphitic film formed by the C+ irradiation; (ii) decreased D retention in a modified tungsten-carbon layer; and (iii) D retention in pure tungsten.

Parallel Spectral Acquisition with an Ion Cyclotron Resonance Cell Array.

PubMed

Park, Sung-Gun; Anderson, Gordon A; Navare, Arti T; Bruce, James E

2016-01-19

Mass measurement accuracy is a critical analytical figure-of-merit in most areas of mass spectrometry application. However, the time required for acquisition of high-resolution, high mass accuracy data limits many applications and is an aspect under continual pressure for development. Current efforts target implementation of higher electrostatic and magnetic fields because ion oscillatory frequencies increase linearly with field strength. As such, the time required for spectral acquisition of a given resolving power and mass accuracy decreases linearly with increasing fields. Mass spectrometer developments to include multiple high-resolution detectors that can be operated in parallel could further decrease the acquisition time by a factor of n, the number of detectors. Efforts described here resulted in development of an instrument with a set of Fourier transform ion cyclotron resonance (ICR) cells as detectors that constitute the first MS array capable of parallel high-resolution spectral acquisition. ICR cell array systems consisting of three or five cells were constructed with printed circuit boards and installed within a single superconducting magnet and vacuum system. Independent ion populations were injected and trapped within each cell in the array. Upon filling the array, all ions in all cells were simultaneously excited and ICR signals from each cell were independently amplified and recorded in parallel. Presented here are the initial results of successful parallel spectral acquisition, parallel mass spectrometry (MS) and MS/MS measurements, and parallel high-resolution acquisition with the MS array system.

Ion trap device

DOEpatents

Ibrahim, Yehia M.; Smith, Richard D.

2016-01-26

An ion trap device is disclosed. The device includes a series of electrodes that define an ion flow path. A radio frequency (RF) field is applied to the series of electrodes such that each electrode is phase shifted approximately 180 degrees from an adjacent electrode. A DC voltage is superimposed with the RF field to create a DC gradient to drive ions in the direction of the gradient. A second RF field or DC voltage is applied to selectively trap and release the ions from the device. Further, the device may be gridless and utilized at high pressure.

Coupling of ions to superconducting circuits

NASA Astrophysics Data System (ADS)

Moeller, Soenke; Daniilidis, Nikos; Haeffner, Hartmut

2013-05-01

We present experimental progress towards coupling the motion of ion strings to the resonant mode of a superconducting high-quality tank circuit. We consider such a coupling as the first step towards interfacing trapped ions with superconducting qubits. In our demonstration experiment, we aim to reduce the temperature of the resonant mode of the tank circuit by extracting energy from the circuit via laser cooling an ion string. One of the main experimental challenges is to construct a tank circuit with such a high quality factor Q that the ion-resonator coupling exceeds the environment-resonator coupling. Currently, we achieve Q = 60 000 at a frequency of ω = 2 π . 5 . 7 MHz . For this mode, the coupling time-scale to the environment is on the order of 50 Hz. We plan to use a trap with an ion-electrode distance on the order of 100 μm resulting in an ion-resonator coupling of 1kHz. This coupling should reduce the electronic temperature of the resonant mode by a factor of 80 below the ambient temperature. For our trap geometry we expect a minimum trap depth of 50 meV for a trap drive frequency of 52 MHz with a 200 V amplitude. This results radial trap frequencies of 5 . 7 MHz . Research funded by DARPA grant #N66001-12-1-4234.

ION SOURCE

DOEpatents

Leland, W.T.

1960-01-01

The ion source described essentially eliminater the problem of deposits of nonconducting materials forming on parts of the ion source by certain corrosive gases. This problem is met by removing both filament and trap from the ion chamber, spacing them apart and outside the chamber end walls, placing a focusing cylinder about the filament tip to form a thin collimated electron stream, aligning the cylinder, slits in the walls, and trap so that the electron stream does not bombard any part in the source, and heating the trap, which is bombarded by electrons, to a temperature hotter than that in the ion chamber, so that the tendency to build up a deposit caused by electron bombardment is offset by the extra heating supplied only to the trap.

Toward Scalable Ion Traps for Quantum Information Processing

DTIC Science & Technology

2010-01-01

3/033031 Abstract. In this paper, we report the design, fabrication and preliminary testing of a 150 zone ion trap array built in a ‘ surface ...gates [4–6]. We report here on the design, fabrication and preliminary testing of a large array built in a ‘ surface -electrode’ geometry [7, 8] and...report the first transport of atomic ions through a surface -electrode trap junction. Transport of ions through a junction has been demonstrated previously

Loading an Equidistant Ion Chain in a Ring Shaped Surface Trap and Anomalous Heating Studies with a High Optical Access Trap

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tabakov, Boyan

2015-07-01

Microfabricated segmented surface ion traps are one viable avenue to scalable quantum information processing. At Sandia National Laboratories we design, fabricate, and characterize such traps. Our unique fabrication capabilities allow us to design traps that facilitate tasks beyond quantum information processing. The design and performance of a trap with a target capability of storing hundreds of equally spaced ions on a ring is described. Such a device could aid experimental studies of phenomena as diverse as Hawking radiation, quantum phase transitions, and the Aharonov - Bohm effect. The fabricated device is demonstrated to hold a ~ 400 ion circular crystal,more » with 9 μm average spacing between ions. The task is accomplished by first characterizing undesired electric fields in the trapping volume and then designing and applying an electric field that substantially reduces the undesired fields. In addition, experimental efforts are described to reduce the motional heating rates in a surface trap by low energy in situ argon plasma treatment that reduces the amount of surface contaminants. The experiment explores the premise that carbonaceous compounds present on the surface contribute to the anomalous heating of secular motion modes in surface traps. This is a research area of fundamental interest to the ion trapping community, as heating adversely affects coherence and thus gate fidelity. The device used provides high optical laser access, substantially reducing scatter from the surface, and thus charging that may lead to excess micromotion. Heating rates for different axial mode frequencies are compared before and after plasma treatment. The presence of a carbon source near the plasma prevents making a conclusion on the observed absence of change in heating rates.« less

Removal of nickel from electroplating rinse waters using electrostatic shielding electrodialysis/electrodeionization.

PubMed

Dermentzis, Konstantinos

2010-01-15

Electrostatic shielding zones made of electrode graphite powder were used as a new type of ionic and electronic current sinks. Because of the local elimination of the applied electric field, voltage and current within the zones, ions are led inside them and accumulate there. The current sinks were implemented in electrostatic shielding electrodialysis of a simulated nickel plating rinse water containing 100 mg L(-1) nickel and electrodeionization of a 0.001 M NiSO(4) solution with simultaneous electrochemical regeneration of the ion exchange resin beds. Pure water was obtained with a Ni(2+) ion concentration of less than 0.1 mg L(-1) at a flow rate of 2.02 x 10(-4)dm(3)s(-1) diluate stream and a current density of 30 Am(-2).

Trapped-ion quantum logic gates based on oscillating magnetic fields.

PubMed

Ospelkaus, C; Langer, C E; Amini, J M; Brown, K R; Leibfried, D; Wineland, D J

2008-08-29

Oscillating magnetic fields and field gradients can be used to implement single-qubit rotations and entangling multiqubit quantum gates for trapped-ion quantum information processing (QIP). With fields generated by currents in microfabricated surface-electrode traps, it should be possible to achieve gate speeds that are comparable to those of optically induced gates for realistic distances between the ion crystal and the electrode surface. Magnetic-field-mediated gates have the potential to significantly reduce the overhead in laser-beam control and motional-state initialization compared to current QIP experiments with trapped ions and will eliminate spontaneous scattering, a fundamental source of decoherence in laser-mediated gates.

Achieving Translationally Invariant Trapped Ion Rings

NASA Astrophysics Data System (ADS)

Urban, Erik; Li, Hao-Kun; Noel, Crystal; Hemmerling, Boerge; Zhang, Xiang; Haeffner, Hartmut

2017-04-01

We present the design and implementation of a novel surface ion trap design in a ring configuration. By eliminating the need for wire bonds through the use of electrical vias and using a rotationally invariant electrode configuration, we have realized a trap that is able to trap up to 20 ions in a ring geometry 45um in diameter, 400um above the trap surface. This large trapping height to ring diameter ratio allows for global addressing of the ring with both lasers and electric fields in the chamber, thereby increasing our ability to control the ring as a whole. Applying compensating electric fields, we measure very low tangential trap frequencies (less than 20kHz) corresponding to rotational barriers down to 4mK. This measurement is currently limited by the temperature of the ions but extrapolation indicates the barrier can be reduced much further with more advanced cooling techniques. Finally, we show that we are able to reduce this energy barrier sufficiently such that the ions are able to overcome it either through thermal motion or rotational motion and delocalize over the full extent of the ring. This work was funded by the Keck Foundation and the NSF.

Heating of ions to superthermal energies in the topside ionosphere by electrostatic ion cyclotron waves

NASA Technical Reports Server (NTRS)

Ungstrup, E.; Klumpar, D. M.; Heikkila, W. J.

1979-01-01

The soft particle spectrometer on the Isis 2 spacecraft occasionally observes fluxes of ions moving upward out of the ionosphere in the vicinity of the auroral oval. These ion fluxes are characterized by a sharp pitch angle distribution usually peaked at an angle somewhat greater than 90 deg, indicative of particles heated to a large transverse temperature in a narrow range below the spacecraft. The observations are interpreted in terms of electrostatic ion cyclotron waves, which heat the ions to superthermal energies transverse to the earth's magnetic field. When the transverse energy increases, the repulsive force of the earth's magnetic field, proportional to the particle magnetic moment, repels the particles away from the earth.

A small electron beam ion trap/source facility for electron/neutral–ion collisional spectroscopy in astrophysical plasmas

NASA Astrophysics Data System (ADS)

Liang, Gui-Yun; Wei, Hui-Gang; Yuan, Da-Wei; Wang, Fei-Lu; Peng, Ji-Min; Zhong, Jia-Yong; Zhu, Xiao-Long; Schmidt, Mike; Zschornack, Günter; Ma, Xin-Wen; Zhao, Gang

2018-01-01

Spectra are fundamental observation data used for astronomical research, but understanding them strongly depends on theoretical models with many fundamental parameters from theoretical calculations. Different models give different insights for understanding a specific object. Hence, laboratory benchmarks for these theoretical models become necessary. An electron beam ion trap is an ideal facility for spectroscopic benchmarks due to its similar conditions of electron density and temperature compared to astrophysical plasmas in stellar coronae, supernova remnants and so on. In this paper, we will describe the performance of a small electron beam ion trap/source facility installed at National Astronomical Observatories, Chinese Academy of Sciences.We present some preliminary experimental results on X-ray emission, ion production, the ionization process of trapped ions as well as the effects of charge exchange on the ionization.

A DIM model for sodium cluster-ions interacting with a charged conducting sphere

NASA Astrophysics Data System (ADS)

Kuntz, P. J.

A diatomics-in-molecules (DIM) model for the energy, shape and charge distribution of metal cluster ions in the presence of a charged insulated conducting sphere is presented. The electrostatic interaction between the sphere and the cluster-ion is introduced in a self-consistent manner which allows the sphere to be polarized by the ion and the ion by the sphere. This interaction appears in the diagonal elements of the model Hamiltonian matrix in such a way that the lowest eigenvalue includes the correct electrostatic energy for the charge distribution in the ground state. The model is applied to the calculation of fusion barriers for Na+2 and Na+3 ions. When both the charge distribution and the geometric configuration of the cluster-ion are allowed to relax freely, the energy as a function of distance from the sphere is nearly the same as that calculated from the electrostatic energy alone, which implies that details of the molecular structure of the cluster-ion can be neglected in calculating fusion barriers from charge polarization alone. That the fusion barriers lie sufficiently far away from the sphere so that the molecule does not dissociate under the influence of the Coulomb interaction confirms that it is meaningful to speak of two separate entities at the barrier position.

On the characteristics of obliquely propagating electrostatic structures in non-Maxwellian plasmas in the presence of ion pressure anisotropy

NASA Astrophysics Data System (ADS)

Adnan, Muhammad; Qamar, Anisa; Mahmood, Shahzad; Kourakis, Ioannis

2017-03-01

The dynamical characteristics of large amplitude ion-acoustic waves are investigated in a magnetized plasma comprising ions presenting space asymmetry in the equation of state and non-Maxwellian electrons. The anisotropic ion pressure is defined using the double adiabatic Chew-Golberger-Low theory. An excess in the superthermal component of the electron population is assumed, in agreement with long-tailed (energetic electron) distribution observations in space plasmas; this is modeled via a kappa-type distribution function. Large electrostatic excitations are assumed to propagate in a direction oblique to the external magnetic field. In the linear (small amplitude) regime, two electrostatic modes are shown to exist. The properties of arbitrary amplitude (nonlinear) obliquely propagating ion-acoustic solitary excitations are thus investigated via a pseudomechanical energy balance analogy, by adopting a Sagdeev potential approach. The combined effect of the ion pressure anisotropy and excess superthermal electrons is shown to alter the parameter region where solitary waves can exist. An excess in the suprathermal particles is thus shown to be associated with solitary waves, which are narrower, faster, and of larger amplitude. Ion pressure anisotropy, on the other hand, affects the amplitude of the solitary waves, which become weaker (in strength), wider (in spatial extension), and thus slower in comparison with the cold ion case.

Long-pore Electrostatics in Inward-rectifier Potassium Channels

PubMed Central

Robertson, Janice L.; Palmer, Lawrence G.; Roux, Benoît

2008-01-01

Inward-rectifier potassium (Kir) channels differ from the canonical K+ channel structure in that they possess a long extended pore (∼85 Å) for ion conduction that reaches deeply into the cytoplasm. This unique structural feature is presumably involved in regulating functional properties specific to Kir channels, such as conductance, rectification block, and ligand-dependent gating. To elucidate the underpinnings of these functional roles, we examine the electrostatics of an ion along this extended pore. Homology models are constructed based on the open-state model of KirBac1.1 for four mammalian Kir channels: Kir1.1/ROMK, Kir2.1/IRK, Kir3.1/GIRK, and Kir6.2/KATP. By solving the Poisson-Boltzmann equation, the electrostatic free energy of a K+ ion is determined along each pore, revealing that mammalian Kir channels provide a favorable environment for cations and suggesting the existence of high-density regions in the cytoplasmic domain and cavity. The contribution from the reaction field (the self-energy arising from the dielectric polarization induced by the ion's charge in the complex geometry of the pore) is unfavorable inside the long pore. However, this is well compensated by the electrostatic interaction with the static field arising from the protein charges and shielded by the dielectric surrounding. Decomposition of the static field provides a list of residues that display remarkable correspondence with existing mutagenesis data identifying amino acids that affect conduction and rectification. Many of these residues demonstrate interactions with the ion over long distances, up to 40 Å, suggesting that mutations potentially affect ion or blocker energetics over the entire pore. These results provide a foundation for understanding ion interactions in Kir channels and extend to the study of ion permeation, block, and gating in long, cation-specific pores. PMID:19001143

Developments on the Toroid Ion Trap Analyzer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lammert, S.A.; Thompson, C.V.; Wise, M.B.

1999-06-13

Investigations into several areas of research have been undertaken to address the performance limitations of the toroid analyzer. The Simion 3D6 (2) ion optics simulation program was used to determine whether the potential well minimum of the toroid trapping field is in the physical center of the trap electrode structure. The results (Figures 1) indicate that the minimum of the potential well is shifted towards the inner ring electrode by an amount approximately equal to 10% of the r0 dimension. A simulation of the standard 3D ion trap under similar conditions was performed as a control. In this case, themore » ions settle to the minimum of the potential well at a point that is coincident with the physical center (both radial and axial) of the trapping electrodes. It is proposed that by using simulation programs, a set of new analyzer electrodes can be fashioned that will correct for the non- linear fields introduced by curving the substantially quadrupolar field about the toroid axis in order to provide a trapping field similar to the 3D ion trap cross- section. A new toroid electrode geometry has been devised to allow the use of channel- tron style detectors in place of the more expensive multichannel plate detector. Two different versions have been designed and constructed - one using the current ion trap cross- section (Figure 2) and another using the linear quedrupole cross- section design first reported by Bier and Syka (3).« less

A rare-earth-magnet ion trap for confining low-Z, bare nuclei

NASA Astrophysics Data System (ADS)

Brewer, Samuel M.; Tan, Joseph N.

2009-05-01

Simplifications in the theory for Rydberg states of hydrogenlike ions allow a substantial improvement in the accuracy of predicted levels, which can yield information on the values of fundamental constants and test theory if they can be compared with precision frequency measurements.[1] We consider the trapping of bare nuclei (fully-stripped) to be used in making Rydberg states of one-electron ions with atomic number 1< Z < 11. Numerical simulation is used here to study ion confinement in a compact, Penning-style ion trap consisting of electrodes integrated with rare-earth permanent magnets, and to model the capture of charge-state-selected ions extracted from an electron beam ion trap (EBIT). An experimental apparatus adapted to the NIST EBIT will also be discussed. Reference: [1] U.D. Jentschura, P.J. Mohr, J.N. Tan, and B.J. Wundt, ``Fundamental constants and tests of theory in Rydberg states of hydrogenlike ions,'' Phys. Rev. Lett. 100, 160404 (2008).

On the multistream approach of relativistic Weibel instability. II. Bernstein-Greene-Kruskal-type waves in magnetic trapping

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ghizzo, A.

2013-08-15

The stationary state with magnetically trapped particles is investigated at the saturation of the relativistic Weibel instability, within the “multiring” model in a Hamiltonian framework. The multistream model and its multiring extension have been developed in Paper I, under the assumption that the generalized canonical momentum is conserved in the perpendicular direction. One dimensional relativistic Bernstein-Greene-Kruskal waves with deeply trapped particles are addressed using similar mathematical formalism developed by Lontano et al.[Phys. Plasmas 9, 2562 (2002); Phys. Plasmas 10, 639 (2003)] using several streams and in the presence of both electrostatic and magnetic trapping mechanisms.

Squeezed coherent states of motion for ions confined in quadrupole and octupole ion traps

NASA Astrophysics Data System (ADS)

Mihalcea, Bogdan M.

2018-01-01

Quasiclassical dynamics of trapped ions is characterized by applying the time dependent variational principle (TDVP) on coherent state orbits, in case of quadrupole and octupole combined (Paul and Penning) or radiofrequency (RF) traps. A dequantization algorithm is proposed, by which the classical Hamilton (energy) function associated to the system results as the expectation value of the quantum Hamiltonian on squeezed coherent states. We develop such method and particularize the quantum Hamiltonian for both combined and RF nonlinear traps, that exhibit axial symmetry. We also build the classical Hamiltonian functions for the particular traps we considered, and find the classical equations of motion.

Toward laser cooling and trapping lanthanum ions

NASA Astrophysics Data System (ADS)

Olmschenk, Steven; Banner, Patrick; Hankes, Jessie; Nelson, Amanda

2017-04-01

Trapped atomic ions are a leading candidate for applications in quantum information. For scalability and applications in quantum communication, it would be advantageous to interface ions with telecom light. We present progress toward laser cooling doubly-ionized lanthanum, which should require only infrared, telecom-compatible light. Since the hyperfine structure of this ion has not been measured, we are using optogalavanic spectroscopy in a hollow cathode lamp to measure the hyperfine spectrum of transitions in lanthanum. Using laser ablation to directly produce ions from a solid target, we laser cool and trap barium ions, and explore extending this technique to lanthanum ions. This research is supported by the Army Research Office, Research Corporation for Science Advancement, and Denison University.

Parallel Transport Quantum Logic Gates with Trapped Ions.

PubMed

de Clercq, Ludwig E; Lo, Hsiang-Yu; Marinelli, Matteo; Nadlinger, David; Oswald, Robin; Negnevitsky, Vlad; Kienzler, Daniel; Keitch, Ben; Home, Jonathan P

2016-02-26

We demonstrate single-qubit operations by transporting a beryllium ion with a controlled velocity through a stationary laser beam. We use these to perform coherent sequences of quantum operations, and to perform parallel quantum logic gates on two ions in different processing zones of a multiplexed ion trap chip using a single recycled laser beam. For the latter, we demonstrate individually addressed single-qubit gates by local control of the speed of each ion. The fidelities we observe are consistent with operations performed using standard methods involving static ions and pulsed laser fields. This work therefore provides a path to scalable ion trap quantum computing with reduced requirements on the optical control complexity.

Recent H- diagnostics, plasma simulations, and 2X scaled Penning ion source developments at the Rutherford Appleton Laboratory

NASA Astrophysics Data System (ADS)

Lawrie, S. R.; Faircloth, D. C.; Smith, J. D.; Sarmento, T. M.; Whitehead, M. O.; Wood, T.; Perkins, M.; Macgregor, J.; Abel, R.

2018-05-01

A vessel for extraction and source plasma analyses is being used for Penning H- ion source development at the Rutherford Appleton Laboratory. A new set of optical elements including an einzel lens has been installed, which transports over 80 mA of H- beam successfully. Simultaneously, a 2X scaled Penning source has been developed to reduce cathode power density. The 2X source is now delivering a 65 mA H- ion beam at 10% duty factor, meeting its design criteria. The long-term viability of the einzel lens and 2X source is now being evaluated, so new diagnostic devices have been installed. A pair of electrostatic deflector plates is used to correct beam misalignment and perform fast chopping, with a voltage rise time of 24 ns. A suite of four quartz crystal microbalances has shown that the cesium flux in the vacuum vessel is only increased by a factor of two, despite the absence of a dedicated cold trap. Finally, an infrared camera has demonstrated good agreement with thermal simulations but has indicated unexpected heating due to beam loss on the downstream electrode. These types of diagnostics are suitable for monitoring all operational ion sources. In addition to experimental campaigns and new diagnostic tools, the high-performance VSim and COMSOL software packages are being used for plasma simulations of two novel ion thrusters for space propulsion applications. In parallel, a VSim framework has been established to include arbitrary temperature and cesium fields to allow the modeling of surface physics in H- ion sources.

Quasi-linear gyrokinetic predictions of the Coriolis momentum pinch in NSTX

DOE Data Explorer

Guttenfelder, W. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Kaye, S. M. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Ren, Y. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Solomon, W. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Bell, R. E. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Candy, J. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Gerhardt, S. P. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); LeBlanc, B. P. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Yuh, H. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)

2016-04-01

This paper presents quasi-linear gyrokinetic predictions of the Coriolis momentum pinch for low aspect-ratio NSTX H-modes where previous experimental measurements were focused. Local, linear calculations predict that in the region of interest (just outside the mid-radius) of these relatively high-beta plasmas, profiles are most unstable to microtearing modes that are only effective in transporting electron energy. However, sub-dominant electromagnetic and electrostatic ballooning modes are also unstable, which are effective at transporting energy, particles and momentum. The quasi-linear prediction of transport from these weaker ballooning modes, assuming they contribute transport in addition to that from microtearing modes in a nonlinear turbulent state, leads to a very small or outward convection of momentum, inconsistent with the experimentally measured inward pinch, and opposite to predictions in conventional aspect ratio tokamaks. Additional predictions of a low beta L-mode plasma, unstable to more traditional electrostatic ion temperature gradient-trapped electron mode instability, show that the Coriolis pinch is inward but remains relatively weak and insensitive to many parameter variations. The weak or outward pinch predicted in NSTX plasmas appears to be at least partially correlated to changes in the parallel mode structure that occur at finite beta and low aspect ratio, as discussed in previous theories. The only conditions identified where a stronger inward pinch is predicted occur either in the purely electrostatic limit or if the aspect ratio is increased. As the Coriolis pinch cannot explain the measured momentum pinch, additional theoretical momentum transport mechanisms are discussed that may be potentially important.

Design of blade-shaped-electrode linear ion traps with reduced anharmonic contributions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Deng, K.; Che, H.; Ge, Y. P.

2015-09-21

RF quadrupole linear Paul traps are versatile tools in quantum physics experiments. Linear Paul traps with blade-shaped electrodes have the advantages of larger solid angles for fluorescence collection. But with these kinds of traps, the existence of higher-order anharmonic terms of the trap potentials can cause large heating rate for the trapped ions. In this paper, we theoretically investigate the dependence of higher-order terms of trap potentials on the geometry of blade-shaped traps, and offer an optimized design. A modified blade electrodes trap is proposed to further reduce higher-order anharmonic terms while still retaining large fluorescence collection angle.

Electrostatic acceleration of helicon plasma using a cusped magnetic field

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harada, S.; Mitsubishi Heavy Industry ltd., 16-5 Konan 2-chome, Minato-ku, Tokyo 108-8215; Baba, T.

2014-11-10

The electrostatic acceleration of helicon plasma is investigated using an electrostatic potential exerted between the ring anode at the helicon source exit and an off-axis hollow cathode in the downstream region. In the downstream region, the magnetic field for the helicon source, which is generated by a solenoid coil, is modified using permanent magnets and a yoke, forming an almost magnetic field-free region surrounded by an annular cusp field. Using a retarding potential analyzer, two primary ion energy peaks, where the lower peak corresponds to the space potential and the higher one to the ion beam, are detected in themore » field-free region. Using argon as the working gas with a helicon power of 1.5 kW and a mass flow rate of 0.21 mg/s, the ion beam energy is on the order of the applied acceleration voltage. In particular, with an acceleration voltage lower than 150 V, the ion beam energy even exceeds the applied acceleration voltage by an amount on the order of the electron thermal energy at the exit of the helicon plasma source. The ion beam energy profile strongly depends on the helicon power and the applied acceleration voltage. Since by this method the whole working gas from the helicon plasma source can, in principle, be accelerated, this device can be applied as a noble electrostatic thruster for space propulsion.« less

Effects of electrostatic interactions on ligand dissociation kinetics

NASA Astrophysics Data System (ADS)

Erbaş, Aykut; de la Cruz, Monica Olvera; Marko, John F.

2018-02-01

We study unbinding of multivalent cationic ligands from oppositely charged polymeric binding sites sparsely grafted on a flat neutral substrate. Our molecular dynamics simulations are suggested by single-molecule studies of protein-DNA interactions. We consider univalent salt concentrations spanning roughly a 1000-fold range, together with various concentrations of excess ligands in solution. To reveal the ionic effects on unbinding kinetics of spontaneous and facilitated dissociation mechanisms, we treat electrostatic interactions both at a Debye-Hückel (DH) (or implicit ions, i.e., use of an electrostatic potential with a prescribed decay length) level and by the more precise approach of considering all ionic species explicitly in the simulations. We find that the DH approach systematically overestimates unbinding rates, relative to the calculations where all ion pairs are present explicitly in solution, although many aspects of the two types of calculation are qualitatively similar. For facilitated dissociation (FD) (acceleration of unbinding by free ligands in solution) explicit-ion simulations lead to unbinding at lower free-ligand concentrations. Our simulations predict a variety of FD regimes as a function of free-ligand and ion concentrations; a particularly interesting regime is at intermediate concentrations of ligands where nonelectrostatic binding strength controls FD. We conclude that explicit-ion electrostatic modeling is an essential component to quantitatively tackle problems in molecular ligand dissociation, including nucleic-acid-binding proteins.

Electrostatic acceleration of helicon plasma using a cusped magnetic field

NASA Astrophysics Data System (ADS)

Harada, S.; Baba, T.; Uchigashima, A.; Yokota, S.; Iwakawa, A.; Sasoh, A.; Yamazaki, T.; Shimizu, H.

2014-11-01

The electrostatic acceleration of helicon plasma is investigated using an electrostatic potential exerted between the ring anode at the helicon source exit and an off-axis hollow cathode in the downstream region. In the downstream region, the magnetic field for the helicon source, which is generated by a solenoid coil, is modified using permanent magnets and a yoke, forming an almost magnetic field-free region surrounded by an annular cusp field. Using a retarding potential analyzer, two primary ion energy peaks, where the lower peak corresponds to the space potential and the higher one to the ion beam, are detected in the field-free region. Using argon as the working gas with a helicon power of 1.5 kW and a mass flow rate of 0.21 mg/s, the ion beam energy is on the order of the applied acceleration voltage. In particular, with an acceleration voltage lower than 150 V, the ion beam energy even exceeds the applied acceleration voltage by an amount on the order of the electron thermal energy at the exit of the helicon plasma source. The ion beam energy profile strongly depends on the helicon power and the applied acceleration voltage. Since by this method the whole working gas from the helicon plasma source can, in principle, be accelerated, this device can be applied as a noble electrostatic thruster for space propulsion.

Charged patchy particle models in explicit salt: Ion distributions, electrostatic potentials, and effective interactions.

PubMed

Yigit, Cemil; Heyda, Jan; Dzubiella, Joachim

2015-08-14

We introduce a set of charged patchy particle models (CPPMs) in order to systematically study the influence of electrostatic charge patchiness and multipolarity on macromolecular interactions by means of implicit-solvent, explicit-ion Langevin dynamics simulations employing the Gromacs software. We consider well-defined zero-, one-, and two-patched spherical globules each of the same net charge and (nanometer) size which are composed of discrete atoms. The studied mono- and multipole moments of the CPPMs are comparable to those of globular proteins with similar size. We first characterize ion distributions and electrostatic potentials around a single CPPM. Although angle-resolved radial distribution functions reveal the expected local accumulation and depletion of counter- and co-ions around the patches, respectively, the orientation-averaged electrostatic potential shows only a small variation among the various CPPMs due to space charge cancellations. Furthermore, we study the orientation-averaged potential of mean force (PMF), the number of accumulated ions on the patches, as well as the CPPM orientations along the center-to-center distance of a pair of CPPMs. We compare the PMFs to the classical Derjaguin-Verwey-Landau-Overbeek theory and previously introduced orientation-averaged Debye-Hückel pair potentials including dipolar interactions. Our simulations confirm the adequacy of the theories in their respective regimes of validity, while low salt concentrations and large multipolar interactions remain a challenge for tractable theoretical descriptions.

Ion Trap Collisional Activation of c and z• Ions Formed via Gas-Phase Ion/Ion Electron Transfer Dissociation

PubMed Central

Han, Hongling; Xia, Yu; McLuckey, Scott A.

2008-01-01

A series of c- and z•-type product ions formed via gas-phase electron transfer ion/ion reactions between protonated polypeptides with azobenzene radical anions are subjected to ion trap collision activation in a linear ion trap. Fragment ions including a-, b-, y-type and ammonia-loss ions are typically observed in collision induced dissociation (CID) of c ions, showing almost identical CID patterns as those of the C-terminal amidated peptides consisting of the same sequences. Collisional activation of z• species mainly gives rise to side-chain losses and peptide backbone cleavages resulting in a-, b-, c-, x-, y-and z-type ions. Most of the fragmentation pathways of z• species upon ion trap CID can be accounted for by radical driven processes. The side-chain losses from z• species are different from the small losses observed from the charge-reduced peptide molecular species in electron transfer dissociation (ETD), which indicates rearrangement of the radical species. Characteristic side-chain losses are observed for several amino acid residues, which are useful to predict their presence in peptide/protein ions. Furthermore, the unique side-chain losses from leucine and isoleucine residues allow facile distinction of these two isomeric residues. PMID:17608403

Ion beam driven ion-acoustic waves in a plasma cylinder with negative ions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sharma, Suresh C.; Gahlot, Ajay

2008-07-15

An ion beam propagating through a magnetized plasma cylinder containing K{sup +} positive ions, electrons, and SF{sub 6}{sup -} negative ions drives electrostatic ion-acoustic (IA) waves to instability via Cerenkov interaction. Two electrostatic IA wave modes in presence of K{sup +} and SF{sub 6}{sup -} ions are studied. The phase velocity of the sound wave in presence of positive and negative ions increase with the relative density of negative ions. The unstable wave frequencies and the growth rate of both the modes in presence of positive and negative ions increase with the relative density of negative ions. The growth ratemore » of both the unstable modes in presence of SF{sub 6}{sup -} and K{sup +} ions scales as the one-third power of the beam density. Numerical calculations of the phase velocity, growth rate, and mode frequencies have been carried out for the parameters of the experiment of Song et al. [Phys. Fluids B 3, 284 (1991)].« less

Polarisation-preserving photon frequency conversion from a trapped-ion-compatible wavelength to the telecom C-band

NASA Astrophysics Data System (ADS)

Krutyanskiy, V.; Meraner, M.; Schupp, J.; Lanyon, B. P.

2017-09-01

We demonstrate polarisation-preserving frequency conversion of single-photon-level light at 854 nm, resonant with a trapped-ion transition and qubit, to the 1550-nm telecom C band. A total photon in / fiber-coupled photon out efficiency of ˜30% is achieved, for a free-running photon noise rate of ˜60 Hz. This performance would enable telecom conversion of 854 nm polarisation qubits, produced in existing trapped-ion systems, with a signal-to-noise ratio greater than 1. In combination with near-future trapped-ion systems, our converter would enable the observation of entanglement between an ion and a photon that has travelled more than 100 km in optical fiber: three orders of magnitude further than the state-of-the-art.

Paul Trapping of Radioactive {sup 6}He{sup +} Ions and Direct Observation of Their {beta} Decay

DOE Office of Scientific and Technical Information (OSTI.GOV)

Flechard, X.; Lienard, E.; Mery, A.

2008-11-21

We demonstrate that abundant quantities of short-lived {beta} unstable ions can be trapped in a novel transparent Paul trap and that their decay products can directly be detected in coincidence. Low energy {sup 6}He{sup +} (807 ms half-life) ions were extracted from the SPIRAL source at GANIL, then decelerated, cooled, and bunched by means of the buffer gas cooling technique. More than 10{sup 8} ions have been stored over a measuring period of six days, and about 10{sup 5} decay coincidences between the beta particles and the {sup 6}Li{sup ++} recoiling ions have been recorded. The technique can be extendedmore » to other short-lived species, opening new possibilities for trap assisted decay experiments.« less

Modified KdV equation for trapped ions in polarized dusty plasma

NASA Astrophysics Data System (ADS)

Singh, K.; Kaur, N.; Sethi, P.; Saini, N. S.

2018-01-01

In this investigation, the effect of polarization force on dust acoustic solitary waves (DASWs) has been presented in a dusty plasma composed of Maxwellian electrons, vortex-like (trapped) ions, and negatively charged mobile dust grains. It has been found that from the Maxwellian ions distribution to a vortex-like one, the dynamics of small but finite amplitude DA solitary waves is governed by a nonlinear equation of modified Korteweg-de Vries (mKdV) type instead of KdV. The combined effect of trapped ions and polarization force strongly influence the characteristics of DASWs. Only rarefactive solitary structures are formed under the influence of ions trapping and polarization force. The implications of our results are useful in real astrophysical situations of space and laboratory dusty plasmas.

Mass and Magnetic Field Dependence of Electrostatic Particle Transport and Turbulence in LAPD-U

NASA Astrophysics Data System (ADS)

Crocker, N. A.; Gilmore, M.; Peebles, W. A.; Will, S.; Nguyen, X. V.; Carter, T. A.

2003-10-01

The scaling of particle transport with ion mass and magnetic field strength remains an open question in plasma research. Direct comparison of experiment with theory is often complicated by inability to significantly vary critical parameters such as ion mass, pressure gradient, ion gyro-radius, etc. The LAPD-U magnetized, linear plasma at UCLA provides the ideal platform for such studies, allowing large parameter variation. The magnetic field in LAPD-U can be varied over a range of 500 - 1500 G, while ion species can be varied to change mass by a factor of at least 10. In addition, ion gyro-radii are small compared to the plasma diameter ( 1 m). Cross-field transport in LAPD-U is thought to be caused by electrostatic turbulence, also a leading candidate for transport in fusion plasmas. It is planned, therefore, to investigate turbulence and transport characteristics as a function of parameter space. In particular, measurement of the mass and magnetic field dependence of electrostatic particle transport and turbulence characteristics in LAPD-U will be presented.

On the stability of the internal kink mode in the banana regime

NASA Astrophysics Data System (ADS)

Fogaccia, G.; Romanelli, F.

1995-01-01

The stability of the internal kink mode is investigated taking into account the kinetic response associated to the trapped thermal ions. Ion-ion collisions and diamagnetic effects in the layer are also considered. A significant stabilizing contribution is obtained, even at low-β values, on the mode, which might be stable, on present experiments, even though predicted unstable according to the Bussac criterion [Bussac et al., Phys. Rev. Lett. 35, 1638 (1975)]. In addition, a trapped-ion instability is found, characterized by mode frequency of the order of the trapped-ion bounce-averaged magnetic drift frequency.

Development of high intensity ion sources for a Tandem-Electrostatic-Quadrupole facility for Accelerator-Based Boron Neutron Capture Therapy.

PubMed

Bergueiro, J; Igarzabal, M; Sandin, J C Suarez; Somacal, H R; Vento, V Thatar; Huck, H; Valda, A A; Repetto, M; Kreiner, A J

2011-12-01

Several ion sources have been developed and an ion source test stand has been mounted for the first stage of a Tandem-Electrostatic-Quadrupole facility For Accelerator-Based Boron Neutron Capture Therapy. A first source, designed, fabricated and tested is a dual chamber, filament driven and magnetically compressed volume plasma proton ion source. A 4 mA beam has been accelerated and transported into the suppressed Faraday cup. Extensive simulations of the sources have been performed using both 2D and 3D self-consistent codes. Copyright © 2011 Elsevier Ltd. All rights reserved.

Existence domain of electrostatic solitary waves in the lunar wake

NASA Astrophysics Data System (ADS)

Rubia, R.; Singh, S. V.; Lakhina, G. S.

2018-03-01

Electrostatic solitary waves (ESWs) and double layers are explored in a four-component plasma consisting of hot protons, hot heavier ions (He++), electron beam, and suprathermal electrons having κ-distribution using the Sagdeev pseudopotential method. Three modes exist: slow and fast ion-acoustic modes and electron-acoustic mode. The occurrence of ESWs and their existence domain as a function of various plasma parameters, such as the number densities of ions and electron beam, the spectral index, κ, the electron beam velocity, the temperatures of ions, and electron beam, are analyzed. It is observed that both the slow and fast ion-acoustic modes support both positive and negative potential solitons as well as their coexistence. Further, they support a "forbidden gap," the region in which the soliton ceases to propagate. In addition, slow ion-acoustic solitons support the existence of both positive and negative potential double layers. The electron-acoustic mode is only found to support negative potential solitons for parameters relevant to the lunar wake plasma. Fast Fourier transform of a soliton electric field produces a broadband frequency spectrum. It is suggested that all three soliton types taken together can provide a good explanation for the observed electrostatic waves in the lunar wake.

Test particle simulation study of whistler wave packets observed near Comet Giacobini-Zinner

NASA Astrophysics Data System (ADS)

Kaya, N.; Matsumoto, H.; Tsurutani, B. T.

1989-01-01

Nonlinear interactions of water group ions with large-amplitude whistler wave packets detected at the leading edge of steepened magnetosonic waves observed near Comet Giacobini-Zinner (GZ) are studied using test particle simulations of water-ion interactions with a model wave based on GZ data. Some of the water ions are found to be decelerated in the steepened portion of the magnetosonic wave to the resonance velocity with the whistler wave packets. Through resonance and related nonlinear interaction with the large-amplitude whistler waves, the water ions become trapped by the packet. An energy balance calculation demonstrates that the trapped ions lose their kinetic energy during the trapped motion in the packet. Thus, the nonlinear trapping motion in the wave structure leads to effective energy transfer from the water group ions to the whistler wave packets in the leading edge of the steepened MHD waves.

Magnetosheath quasi-trapped distributions and ion flows associated with reconnection

NASA Technical Reports Server (NTRS)

Neff, J. E.; Speiser, T. W.; Williams, D. J.

1987-01-01

Using a sample of ISEE 1 and 2 magnetopause crossings previously identified as times of quasi-steady reconnection, flows of medium energy ions in the magnetosheath are identified. The paper then investigates the particle pitch angle distribution immediately before and after each of these events for the signature of quasi-trapped distributions of energetic ions. Several of the ion flows identified were observed simultaneously with previously identified flux transfer events (FTEs). While FTEs identified from the magnetometer tracings typically show evidence of ion flows, the converse is not necessarily true. However, all properties of the magnetosheath ion flows are the same regardless of whether an FTE can be identified from the magnetometer data. Evidence is found for small-scale reconnection processes (FTEs, ion flows) embedded within a larger region of interconnected field, which is traced out by the quasi-trapped particles. Quasi-trapped distributions of medium-energy ions are seen to sandwich reconnection-associated ion flows in the magnetosheath. The results of this survey have been used to suggest a morphology for reconnection events that incorporates both large- and small-scale features.

Nonlinear resonances in linear segmented Paul trap of short central segment.

PubMed

Kłosowski, Łukasz; Piwiński, Mariusz; Pleskacz, Katarzyna; Wójtewicz, Szymon; Lisak, Daniel

2018-03-23

Linear segmented Paul trap system has been prepared for ion mass spectroscopy experiments. A non-standard approach to stability of trapped ions is applied to explain some effects observed with ensembles of calcium ions. Trap's stability diagram is extended to 3-dimensional one using additional ∆a besides standard q and a stability parameters. Nonlinear resonances in (q,∆a) diagrams are observed and described with a proposed model. The resonance lines have been identified using simple simulations and comparing the numerical and experimental results. The phenomenon can be applied in electron-impact ionization experiments for mass-identification of obtained ions or purification of their ensembles. This article is protected by copyright. All rights reserved.

Production of Ar{sup q+} ions with a tandem linear Paul trap

DOE Office of Scientific and Technical Information (OSTI.GOV)

Higaki, H., E-mail: hhigaki@hiroshima-u.ac.jp; Nagayasu, K.; Iwai, T.

A tandem linear Paul trap was used to create highly charged Argon ions by electron impact ionizations. By improving the operation scheme, the production of Ar{sup 4+} ions was confirmed. Possible improvements for the future experiments with laser cooled Ca{sup +} ions are suggested.

ON THE ORIGIN AND PHYSICS OF GAMMA FLARES IN CRAB NEBULA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Machabeli, George; Rogava, Andria; Shapakidze, David, E-mail: andria.rogava@iliauni.edu.ge

We consider parametric generation of electrostatic waves in the magnetosphere of the pulsar PSR0531. The suggested mechanism allows us to convert the pulsar rotational energy into the energy of Langmuir waves. The maximum growth rate is achieved in the “superluminal” area, where the phase velocity of perturbations exceeds the speed of light. Therefore, electromagnetic waves do not damp on particles. Instead, they create plasmon condensate, which is carried out outside of the pulsar magnetosphere and reaches the Crab Nebula. It is shown that the transfer of the energy of the plasmon condensate from the light cylinder to the active regionmore » of the nebula happens practically without losses. Unlike the plasma of the magnetosphere, the one of the nebula contains ions, i.e., it may sustain modulation instability, that leads to the collapse of the Langmuir condensate. Langmuir wave collapse, in turn, leads to the acceleration of the distribution function particles. Furthermore, the processes that lead to self-trapping of the synchrotron radiation are discussed. The self-trapping results in the growth of the radiation intensity, which manifests itself observationally as a flare. The condition for the self-trapping onset is derived, showing that if the phenomenon takes place at 100 MeV, then it does not happen at lower (or higher) energies. This specific kind of higher-/lower-energy cutoff could explain why when we observe the flare at 100 MeV that no enhanced emission is observed at lower/higher energies!.« less

Kinetic features and non-stationary electron trapping in paraxial magnetic nozzles

NASA Astrophysics Data System (ADS)

Sánchez-Arriaga, G.; Zhou, J.; Ahedo, E.; Martínez-Sánchez, M.; Ramos, J. J.

2018-03-01

The paraxial expansion of a collisionless plasma jet into vacuum, guided by a magnetic nozzle, is studied with an Eulerian and non-stationary Vlasov-Poisson solver. Parametric analyzes varying the magnetic field expansion rate, the size of the simulation box, and the electrostatic potential fall are presented. After choosing the potential fall leading to a zero net current beam, the steady states of the simulations exhibit a quasi-neutral region followed by a downstream sheath. The latter, an unavoidable consequence of the finite size of the computational domain, does not affect the quasi-neutral region if the box size is chosen appropriately. The steady state presents a strong decay of the perpendicular temperature of the electrons, whose profile versus the inverse of the magnetic field does not depend on the expansion rate within the quasi-neutral region. As a consequence, the electron distribution function is highly anisotropic downstream. The simulations revealed that the ions reach a higher velocity during the transient than in the steady state and their distribution functions are not far from mono-energetic. The density percentage of the population of electrons trapped during the transient, which is computed self-consistently by the code, is up to 25% of the total electron density in the quasi-neutral region. It is demonstrated that the exact amount depends on the history of the system and the steady state is not unique. Nevertheless, the amount of trapped electrons is smaller than the one assumed heuristically by kinetic stationary theories.

Optical properties of voltage sensitive hemicyanine dyes of variable hydrophobicity confined within surfactant micelles

NASA Astrophysics Data System (ADS)

Naeem, Kashif; Naseem, Bushra; Shah, S. S.; Shah, Syed W. H.

2017-11-01

The optical properties of amphiphilic hemicyanine dyes with variable hydrophobicity, confined within anionic micelles of sodium dodecylbenzenesulfonate (NaDDBS) have been studied by UV-visible absorption spectroscopy. The confinement constant, K conf has been determined for each entrapped dye. The ion-pair formation between dye and surfactant causes a decline in electronic transition energy (ΔE T) when dye alkyl chains are smaller due to stabilization of both the ground and excited state. ΔE T values gradually increase with increase in dye hydrophobicity that hampers the electrostatic interaction with dialkylammonium moiety and consequently excited state stabilization is compromised. The average number of dye molecules trapped in a single micelle was also determined. The negative values of Gibbs free energy indicate that the dye entrapment within micelles is energetically favored. These findings have significance for developing functional materials with peculiar luminescent properties, especially for more effective probing of complex biological systems.

Laser-driven collimated tens-GeV monoenergetic protons from mass-limited target plus preformed channel

NASA Astrophysics Data System (ADS)

Zheng, F. L.; Wu, S. Z.; Wu, H. C.; Zhou, C. T.; Cai, H. B.; Yu, M. Y.; Tajima, T.; Yan, X. Q.; He, X. T.

2013-01-01

Proton acceleration by ultra-intense laser pulse irradiating a target with cross-section smaller than the laser spot size and connected to a parabolic density channel is investigated. The target splits the laser into two parallel propagating parts, which snowplow the back-side plasma electrons along their paths, creating two adjacent parallel wakes and an intense return current in the gap between them. The radiation-pressure pre-accelerated target protons trapped in the wake fields now undergo acceleration as well as collimation by the quasistatic wake electrostatic and magnetic fields. Particle-in-cell simulations show that stable long-distance acceleration can be realized, and a 30 fs monoenergetic ion beam of >10 GeV peak energy and <2° divergence can be produced by a circularly polarized laser pulse at an intensity of about 1022 W/cm2.

Electrostatic ion-cyclotron waves in a nonuniform magnetic field

NASA Technical Reports Server (NTRS)

Cartier, S. L.; Dangelo, N.; Merlino, R. L.

1985-01-01

The properties of electrostatic ion-cyclotron waves excited in a single-ended cesium Q machine with a nonuniform magnetic field are described. The electrostatic ion-cyclotron waves are generated in the usual manner by drawing an electron current to a small exciter disk immersed in the plasma column. The parallel and perpendicular (to B) wavelengths and phase velocities are determined by mapping out two-dimensional wave phase contours. The wave frequency f depends on the location of the exciter disk in the nonuniform magnetic field, and propagating waves are only observed in the region where f is approximately greater than fci, where fci is the local ion-cyclotron frequency. The parallel phase velocity is in the direction of the electron drift. From measurements of the plasma properties along the axis, it is inferred that the electron drift velocity is not uniform along the entire current channel. The evidence suggests that the waves begin being excited at that axial position where the critical drift velocity is first exceeded, consistent with a current-driven excitation mechanism.

ISEE 1 observations of electrostatic ion cyclotron waves in association with ion beams on auroral field lines from about 2.5 to 4.5 R(E)

NASA Technical Reports Server (NTRS)

Catell, C. A.; Mozer, F. S.; Roth, I.; Anderson, R. R.; Elphic, R. C.

1991-01-01

Quasi-monochromatic waves at about the hydrogen cyclotron frequency were observed as the ISEE 1 satellite traversed auroral field lines at radial distances of about 2.5-4.5 R(E) near midnight on June 19, 1981. Waves and both lower and higher frequencies were observed at higher altitudes, and possible electrostatic helium cyclotron and oxygen cyclotron waves occurred at lower altitudes. Upflowing hydrogen and oxygen beams and field-aligned currents occurred simultaneously. The features of the waves are most consistent with the current-driven mode. In addition, numerical studies of the linear dispersion relation, using parameters based on the observations, show that both the parallel and oblique two-stream modes and the ion-beam-driven modes were stable while oblique current-driven modes were unstable. The O(+) and H(+) distributions provide evidence for interactions with local electrostatic ion cyclotron waves and for the H(+)-O(+) two-stream instability at altitudes below the satellite.

A highly miniaturized vacuum package for a trapped ion atomic clock

DOE PAGES

Schwindt, Peter D. D.; Jau, Yuan-Yu; Partner, Heather; ...

2016-05-12

We report on the development of a highly miniaturized vacuum package for use in an atomic clock utilizing trapped ytterbium-171 ions. The vacuum package is approximately 1 cm 3 in size and contains a linear quadrupole RF Paul ion trap, miniature neutral Yb sources, and a non-evaporable getter pump. We describe the fabrication process for making the Yb sources and assembling the vacuum package. To prepare the vacuum package for ion trapping, it was evacuated, baked at a high temperature, and then back filled with a helium buffer gas. Once appropriate vacuum conditions were achieved in the package, the packagemore » was sealed with a copper pinch-off and was then pumped only by the non-evaporable getter. We demonstrated ion trapping in this vacuum package and the operation of an atomic clock, stabilizing a local oscillator to the 12.6 GHz hyperfine transition of 171Yb +. The fractional frequency stability of the clock was measured to be 2 × 10 -11 / τ 1/2.« less

Technology for On-Chip Qubit Control with Microfabricated Surface Ion Traps

DOE Office of Scientific and Technical Information (OSTI.GOV)

Highstrete, Clark; Scott, Sean Michael; Nordquist, Christopher D.

2013-11-01

Trapped atomic ions are a leading physical system for quantum information processing. However, scalability and operational fidelity remain limiting technical issues often associated with optical qubit control. One promising approach is to develop on-chip microwave electronic control of ion qubits based on the atomic hyperfine interaction. This project developed expertise and capabilities at Sandia toward on-chip electronic qubit control in a scalable architecture. The project developed a foundation of laboratory capabilities, including trapping the 171Yb + hyperfine ion qubit and developing an experimental microwave coherent control capability. Additionally, the project investigated the integration of microwave device elements with surface ionmore » traps utilizing Sandia’s state-of-the-art MEMS microfabrication processing. This effort culminated in a device design for a multi-purpose ion trap experimental platform for investigating on-chip microwave qubit control, laying the groundwork for further funded R&D to develop on-chip microwave qubit control in an architecture that is suitable to engineering development.« less

Dipolar DC Collisional Activation in a "Stretched" 3-D Ion Trap: The Effect of Higher Order Fields on rf-Heating

NASA Astrophysics Data System (ADS)

Prentice, Boone M.; McLuckey, Scott A.

2012-04-01

Applying dipolar DC (DDC) to the end-cap electrodes of a 3-D ion trap operated with a bath gas at roughly 1 mTorr gives rise to `rf-heating' and can result in collision-induced dissociation (CID). This approach to ion trap CID differs from the conventional single-frequency resonance excitation approach in that it does not rely on tuning a supplementary frequency to coincide with the fundamental secular frequeny of the precursor ion of interest. Simulations using the program ITSIM 5.0 indicate that application of DDC physically displaces ions solely in the axial (inter end-cap) dimension whereupon ion acceleration occurs via power absorption from the drive rf. Experimental data shows that the degree of rf-heating in a stretched 3-D ion trap is not dependent solely on the ratio of the dipolar DC voltage/radio frequency (rf) amplitude, as a model based on a pure quadrupole field suggests. Rather, ion temperatures are shown to increase as the absolute values of the dipolar DC and rf amplitude both decrease. Simulations indicate that the presence of higher order multi-pole fields underlies this unexpected behavior. These findings have important implications for the use of DDC as a broad-band activation approach in multi-pole traps.

Experimental quantum simulations of many-body physics with trapped ions.

PubMed

Schneider, Ch; Porras, Diego; Schaetz, Tobias

2012-02-01

Direct experimental access to some of the most intriguing quantum phenomena is not granted due to the lack of precise control of the relevant parameters in their naturally intricate environment. Their simulation on conventional computers is impossible, since quantum behaviour arising with superposition states or entanglement is not efficiently translatable into the classical language. However, one could gain deeper insight into complex quantum dynamics by experimentally simulating the quantum behaviour of interest in another quantum system, where the relevant parameters and interactions can be controlled and robust effects detected sufficiently well. Systems of trapped ions provide unique control of both the internal (electronic) and external (motional) degrees of freedom. The mutual Coulomb interaction between the ions allows for large interaction strengths at comparatively large mutual ion distances enabling individual control and readout. Systems of trapped ions therefore exhibit a prominent system in several physical disciplines, for example, quantum information processing or metrology. Here, we will give an overview of different trapping techniques of ions as well as implementations for coherent manipulation of their quantum states and discuss the related theoretical basics. We then report on the experimental and theoretical progress in simulating quantum many-body physics with trapped ions and present current approaches for scaling up to more ions and more-dimensional systems.

Invited review article: the electrostatic plasma lens.

PubMed

Goncharov, Alexey

2013-02-01

The fundamental principles, experimental results, and potential applications of the electrostatic plasma lens for focusing and manipulating high-current, energetic, heavy ion beams are reviewed. First described almost 50 years ago, this optical beam device provides space charge neutralization of the ion beam within the lens volume, and thus provides an effective and unique tool for focusing high current beams where a high degree of neutralization is essential to prevent beam blow-up. Short and long lenses have been explored, and a lens in which the magnetic field is provided by rare-earth permanent magnets has been demonstrated. Applications include the use of this kind of optical tool for laboratory ion beam manipulation, high dose ion implantation, heavy ion accelerator injection, in heavy ion fusion, and other high technology.

Stimulated Brillouin scatter in a magnetized ionospheric plasma.

PubMed

Bernhardt, P A; Selcher, C A; Lehmberg, R H; Rodriguez, S P; Thomason, J F; Groves, K M; McCarrick, M J; Frazer, G J

2010-04-23

High power electromagnetic waves transmitted from the HAARP facility in Alaska can excite low-frequency electrostatic waves by magnetized stimulated Brillouin scatter. Either an ion-acoustic wave with a frequency less than the ion cyclotron frequency (f(CI)) or an electrostatic ion cyclotron (EIC) wave just above f(CI) can be produced. The coupled equations describing the magnetized stimulated Brillouin scatter instability show that the production of both ion-acoustic and EIC waves is strongly influenced by the wave propagation relative to the background magnetic field. Experimental observations of stimulated electromagnetic emissions using the HAARP transmitter have confirmed that only ion-acoustic waves are excited for propagation along the magnetic zenith and that EIC waves can only be detected with oblique propagation angles. The ion composition can be obtained from the measured EIC frequency.

New high-resolution electrostatic ion mass analyzer using time of flight

NASA Technical Reports Server (NTRS)

Hamilton, D. C.; Gloeckler, G.; Ipavich, F. M.; Lundgren, R. A.; Sheldon, R. B.

1990-01-01

The design of a high-resolution ion-mass analyzer is described, which is based on an accurate measurement of the time of flight (TOF) of ions within a region configured to produce a harmonic potential. In this device, the TOF, which is independent of ion energy, is determined from a start pulse from secondary electrons produced when the ion passes through a thin carbon foil at the entrance of the TOF region and at a stop pulse from the ion striking a microchannel plate upon exciting the region. A laboratory prototype instrument called 'VMASS' was built and was tested at the Goddard Space Flight Center electrostatic accelerator, showing a good mass resolution of the instrument. Sensors of the VMASS type will form part of the WIND Solar Wind and Suprathermal Ion experiment, the Soho mission, and the Advanced Composition Explorer.

Fused Silica Ion Trap Chip with Efficient Optical Collection System for Timekeeping, Sensing, and Emulation

DTIC Science & Technology

2015-01-22

applications in fast single photon sources, quantum repeater circuitry, and high fidelity remote entanglement of atoms for quantum information protocols. We...fluorescence for motion/force sensors through Doppler velocimetry; and for the efficient collection of single photons from trapped ions for...Doppler velocimetry; and for the efficient collection of single photons from trapped ions for applications in fast single photon sources, quantum

Ion-trajectory analysis for micromotion minimization and the measurement of small forces

NASA Astrophysics Data System (ADS)

Gloger, Timm F.; Kaufmann, Peter; Kaufmann, Delia; Baig, M. Tanveer; Collath, Thomas; Johanning, Michael; Wunderlich, Christof

2015-10-01

For experiments with ions confined in a Paul trap, minimization of micromotion is often essential. In order to diagnose and compensate micromotion we have implemented a method that allows for finding the position of the radio-frequency (rf) null reliably and efficiently, in principle, without any variation of direct current (dc) voltages. We apply a trap modulation technique and focus-scanning imaging to extract three-dimensional ion positions for various rf drive powers and analyze the power dependence of the equilibrium position of the trapped ion. In contrast to commonly used methods, the search algorithm directly makes use of a physical effect as opposed to efficient numerical minimization in a high-dimensional parameter space. Using this method we achieve a compensation of the residual electric field that causes excess micromotion in the radial plane of a linear Paul trap down to 0.09 Vm-1 . Additionally, the precise position determination of a single harmonically trapped ion employed here can also be utilized for the detection of small forces. This is demonstrated by determining light pressure forces with a precision of 135 yN. As the method is based on imaging only, it can be applied to several ions simultaneously and is independent of laser direction and thus well suited to be used with, for example, surface-electrode traps.

Radioactive Barium Ion Trap Based on Metal-Organic Framework for Efficient and Irreversible Removal of Barium from Nuclear Wastewater.

PubMed

Peng, Yaguang; Huang, Hongliang; Liu, Dahuan; Zhong, Chongli

2016-04-06

Highly efficient and irreversible capture of radioactive barium from aqueous media remains a serious task for nuclear waste disposal and environmental protection. To address this task, here we propose a concept of barium ion trap based on metal-organic framework (MOF) with a strong barium-chelating group (sulfate and sulfonic acid group) in the pore structures of MOFs. The functionalized MOF-based ion traps can remove >90% of the barium within the first 5 min, and the removal efficiency reaches 99% after equilibrium. Remarkably, the sulfate-group-functionalized ion trap demonstrates a high barium uptake capacity of 131.1 mg g(-1), which surpasses most of the reported sorbents and can selectively capture barium from nuclear wastewater, whereas the sulfonic-acid-group-functionalized ion trap exhibits ultrafast kinetics with a kinetic rate constant k2 of 27.77 g mg(-1) min(-1), which is 1-3 orders of magnitude higher than existing sorbents. Both of the two MOF-based ion traps can capture barium irreversibly. Our work proposes a new strategy to design barium adsorbent materials and provides a new perspective for removing radioactive barium and other radionuclides from nuclear wastewater for environment remediation. Besides, the concrete mechanisms of barium-sorbent interactions are also demonstrated in this contribution.

Development of a united-atom force field for 1-ethyl-3-methylimidazolium tetracyanoborate ionic liquid

NASA Astrophysics Data System (ADS)

Koller, Thomas; Ramos, Javier; Garrido, Nuno M.; Fröba, Andreas P.; Economou, Ioannis G.

2012-06-01

Three united-atom (UA) force fields are presented for the ionic liquid 1-ethyl-3-methylimidazolium tetracyanoborate, abbreviated as [EMIM]+[B(CN)4]-. The atomistic charges were calculated based on the restrained electrostatic potential (RESP) of the isolated ions (abbreviated as force field 1, FF-1) and the ensemble averaged RESP (EA-RESP) method from the most stable ion pair configurations obtained by MP2/6-31G*+ calculations (abbreviated as FF-2 and FF-3). Non-electrostatic parameters for both ions were taken from the literature and Lennard-Jones parameters for the [B(CN)4]- anion were fitted in two different ways to reproduce the experimental liquid density. Molecular dynamics (MD) simulations were performed over a wide temperature range to identify the effect of the electrostatic and non-electrostatic potential on the liquid density and on transport properties such as self-diffusion coefficient and viscosity. Predicted liquid densities for the three parameter sets deviate less than 0.5% from experimental data. The molecular mobility with FF-2 and FF-3 using reduced charge sets is appreciably faster than that obtained with FF-1. FF-3 presents a refined non-electrostatic potential that leads to a notable improvement in both transport properties when compared to experimental data.

Magnetic field design for a Penning ion source for a 200 keV electrostatic accelerator

NASA Astrophysics Data System (ADS)

Fathi, A.; Feghhi, S. A. H.; Sadati, S. M.; Ebrahimibasabi, E.

2017-04-01

In this study, the structure of magnetic field for a Penning ion source has been designed and constructed with the use of permanent magnets. The ion source has been designed and constructed for a 200 keV electrostatic accelerator. With using CST Studio Suite, the magnetic field profile inside the ion source was simulated and an appropriate magnetic system was designed to improve particle confinement. Designed system consists of two ring magnets with 9 mm distance from each other around the anode. The ion source was constructed and the cylindrical magnet and designed magnetic system were tested on the ion source. The results showed that the ignition voltage for ion source with the designed magnetic system is almost 300 V lower than the ion source with the cylindrical magnet. Better particle confinement causes lower voltage discharge to occur.

IEC Thrusters for Space Probe Applications and Propulsion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miley, George H.; Momota, Hiromu; Wu Linchun

Earlier conceptual design studies (Bussard, 1990; Miley et al., 1998; Burton et al., 2003) have described Inertial Electrostatic Confinement (IEC) fusion propulsion to provide a high-power density fusion propulsion system capable of aggressive deep space missions. However, this requires large multi-GW thrusters and a long term development program. As a first step towards this goal, a progression of near-term IEC thrusters, stating with a 1-10 kWe electrically-driven IEC jet thruster for satellites are considered here. The initial electrically-powered unit uses a novel multi-jet plasma thruster based on spherical IEC technology with electrical input power from a solar panel. In thismore » spherical configuration, Xe ions are generated and accelerated towards the center of double concentric spherical grids. An electrostatic potential well structure is created in the central region, providing ion trapping. Several enlarged grid opening extract intense quasi-neutral plasma jets. A variable specific impulse in the range of 1000-4000 seconds is achieved by adjusting the grid potential. This design provides high maneuverability for satellite and small space probe operations. The multiple jets, combined with gimbaled auxiliary equipment, provide precision changes in thrust direction. The IEC electrical efficiency can match or exceed efficiencies of conventional Hall Current Thrusters (HCTs) while offering advantages such as reduced grid erosion (long life time), reduced propellant leakage losses (reduced fuel storage), and a very high power-to-weight ratio. The unit is ideally suited for probing missions. The primary propulsive jet enables delicate maneuvering close to an object. Then simply opening a second jet offset 180 degrees from the propulsion one provides a 'plasma analytic probe' for interrogation of the object.« less

Imaging and Rapid-Scanning Ion Mass Spectrometer (IRM) for the CASSIOPE e-POP Mission

NASA Astrophysics Data System (ADS)

Yau, Andrew W.; Howarth, Andrew; White, Andrew; Enno, Greg; Amerl, Peter

2015-06-01

The imaging and rapid-scanning ion mass spectrometer (IRM) is part of the Enhanced Polar Outflow Probe (e-POP) instrument suite on the Canadian CASSIOPE small satellite. Designed to measure the composition and detailed velocity distributions of ions in the ˜1-100 eV/q range on a non-spinning spacecraft, the IRM sensor consists of a planar entrance aperture, a pair of electrostatic deflectors, a time-of-flight (TOF) gate, a hemispherical electrostatic analyzer, and a micro-channel plate (MCP) detector. The TOF gate measures the transit time of each detected ion inside the sensor. The hemispherical analyzer disperses incident ions by their energy-per-charge and azimuth in the aperture plane onto the detector. The two electrostatic deflectors may be optionally programmed to step through a sequence of deflector voltages, to deflect ions of different incident elevation out of the aperture plane and energy-per-charge into the sensor aperture for sampling. The position and time of arrival of each detected ion at the detector are measured, to produce an image of 2-dimensional (2D), mass-resolved ion velocity distribution up to 100 times per second, or to construct a composite 3D velocity distribution by combining successive images in a deflector voltage sequence. The measured distributions are then used to investigate ion composition, density, drift velocity and temperature in polar ion outflows and related acceleration and transport processes in the topside ionosphere.

Magnetosheath electrostatic turbulence

NASA Technical Reports Server (NTRS)

Rodriquez, P.

1977-01-01

The spectrum of electrostatic plasma waves in the terrestrial magnetosheath was studied using the plasma wave experiment on the IMP-6 satellite. Electrostatic plasma wave turbulence is almost continuously present throughout the magnetosheath with broadband (20 Hz- 70 kHz) r.m.s. field intensities typically 0.01 - 1.0 millivolts/m. Peak intensities of about 1.0 millivolts/m near the electron plasma frequency (30 - 60 kHz) were detected occasionally. The components usually identified in the spectrum of magnetosheath electrostatic turbulence include a high frequency ( or = 30 kHz) component peaking at the electron plasma frequency f sub pe, a low frequency component with a broad intensity maximum below the nominal ion plasma frequency f sub pi (approximately f sub pe/43), and a less well defined intermediate component in the range f sub pi f f sub pe. The intensity distribution of magnetosheath electrostatic turbulence clearly shows that the low frequency component is associated with the bow shock, suggesting that the ion heating begun at the shock continues into the downstream magnetosheath.

Single Qubit Manipulation in a Microfabricated Surface Electrode Ion Trap (Open Access, Publisher’s Version)

DTIC Science & Technology

2013-09-13

electric fields due to charge build up on the vacuum viewport. For some experiments a non-evaporable getter (NEG) pump is placed 3.3mm away from the...trap, between the trap and the solid aluminum ground shield, to reduce the vacuum pressure close to the ion. The vacuum chamber is constantly pumped by...an ion pump , a titanium sublimation pump and the NEG pump . The pressure of the vacuum system was below what is measurable by the ion gage used (ə.9

Ion trap simulations of quantum fields in an expanding universe.

PubMed

Alsing, Paul M; Dowling, Jonathan P; Milburn, G J

2005-06-10

We propose an experiment in which the phonon excitation of ion(s) in a trap, with a trap frequency exponentially modulated at rate kappa, exhibits a thermal spectrum with an "Unruh" temperature given by k(B)T=Planck kappa. We discuss the similarities of this experiment to the response of detectors in a de Sitter universe and the usual Unruh effect for uniformly accelerated detectors. We demonstrate a new Unruh effect for detectors that respond to antinormally ordered moments using the ion's first blue sideband transition.

Adaptation of a 3-D Quadrupole Ion Trap for Dipolar DC Collisional Activation

PubMed Central

Prentice, Boone M.; Santini, Robert E.; McLuckey, Scott A.

2011-01-01

Means to allow for the application of a dipolar DC pulse to the end-cap electrodes of a three-dimensional (3-D) quadrupole ion trap for as short as a millisecond to as long as hundreds of milliseconds are described. The implementation of dipolar DC does not compromise the ability to apply AC waveforms to the end-cap electrodes at other times in the experiment. Dipolar DC provides a nonresonant means for ion acceleration by displacing ions from the center of the ion trap where they experience stronger rf electric fields, which increases the extent of micro-motion. The evolution of the product ion spectrum to higher generation products with time, as shown using protonated leucine enkephalin as a model protonated peptide, illustrates the broad-band nature of the activation. Dipolar DC activation is also shown to be effective as an ion heating approach in mimicking high amplitude short time excitation (HASTE)/pulsed Q dissociation (PQD) resonance excitation experiments that are intended to enhance the likelihood for observing low m/z products in ion trap tandem mass spectrometry. PMID:21953251

Precise positioning of an ion in an integrated Paul trap-cavity system using radiofrequency signals

NASA Astrophysics Data System (ADS)

Kassa, Ezra; Takahashi, Hiroki; Christoforou, Costas; Keller, Matthias

2018-03-01

We report a novel miniature Paul ion trap design with an integrated optical fibre cavity which can serve as a building block for a fibre-linked quantum network. In such cavity quantum electrodynamic set-ups, the optimal coupling of the ions to the cavity mode is of vital importance and this is achieved by moving the ion relative to the cavity mode. The trap presented herein features an endcap-style design complemented with extra electrodes on which additional radiofrequency voltages are applied to fully control the pseudopotential minimum in three dimensions. This method lifts the need to use three-dimensional translation stages for moving the fibre cavity with respect to the ion and achieves high integrability, mechanical rigidity and scalability. Not based on modifying the capacitive load of the trap, this method leads to precise control of the pseudopotential minimum allowing the ion to be moved with precisions limited only by the ion's position spread. We demonstrate this by coupling the ion to the fibre cavity and probing the cavity mode profile.

An apparatus for immersing trapped ions into an ultracold gas of neutral atoms

NASA Astrophysics Data System (ADS)

Schmid, Stefan; Härter, Arne; Frisch, Albert; Hoinka, Sascha; Denschlag, Johannes Hecker

2012-05-01

We describe a hybrid vacuum system in which a single ion or a well-defined small number of trapped ions (in our case Ba+ or Rb+) can be immersed into a cloud of ultracold neutral atoms (in our case Rb). This apparatus allows for the study of collisions and interactions between atoms and ions in the ultracold regime. Our setup is a combination of a Bose-Einstein condensation apparatus and a linear Paul trap. The main design feature of the apparatus is to first separate the production locations for the ion and the ultracold atoms and then to bring the two species together. This scheme has advantages in terms of stability and available access to the region where the atom-ion collision experiments are carried out. The ion and the atoms are brought together using a moving one-dimensional optical lattice transport which vertically lifts the atomic sample over a distance of 30 cm from its production chamber into the center of the Paul trap in another chamber. We present techniques to detect and control the relative position between the ion and the atom cloud.

Sideband cooling of small ion Coulomb crystals in a Penning trap

NASA Astrophysics Data System (ADS)

Stutter, G.; Hrmo, P.; Jarlaud, V.; Joshi, M. K.; Goodwin, J. F.; Thompson, R. C.

2018-03-01

We have recently demonstrated the laser cooling of a single ? ion to the motional ground state in a Penning trap using the resolved-sideband cooling technique on the electric quadrupole transition S? D?. Here we report on the extension of this technique to small ion Coulomb crystals made of two or three ? ions. Efficient cooling of the axial motion is achieved outside the Lamb-Dicke regime on a two-ion string along the magnetic field axis as well as on two- and three-ion planar crystals. Complex sideband cooling sequences are required in order to cool both axial degrees of freedom simultaneously. We measure a mean excitation after cooling of ? for the centre of mass (COM) mode and ? for the breathing mode of the two-ion string with corresponding heating rates of 11(2) ? and ? at a trap frequency of 162 kHz. The occupation of the ground state of the axial modes (?) is above 75% for the two-ion planar crystal and the associated heating rates 0.8(5) ? at a trap frequency of 355 kHz.

Observation of enhanced radial transport of energetic ion due to energetic particle mode destabilized by helically-trapped energetic ion in the Large Helical Device

NASA Astrophysics Data System (ADS)

Ogawa, K.; Isobe, M.; Kawase, H.; Nishitani, T.; Seki, R.; Osakabe, M.; LHD Experiment Group

2018-04-01

A deuterium experiment was initiated to achieve higher-temperature and higher-density plasmas in March 2017 in the Large Helical Device (LHD). The central ion temperature notably increases compared with that in hydrogen experiments. However, an energetic particle mode called the helically-trapped energetic-ion-driven resistive interchange (EIC) mode is often excited by intensive perpendicular neutral beam injections on high ion-temperature discharges. The mode leads to significant decrease of the ion temperature or to limiting the sustainment of the high ion-temperature state. To understand the effect of EIC on the energetic ion confinement, the radial transport of energetic ions is studied by means of the neutron flux monitor and vertical neutron camera newly installed on the LHD. Decreases of the line-integrated neutron profile in core channels show that helically-trapped energetic ions are lost from the plasma.

Ion Transport through Membrane-Spanning Nanopores Studied by Molecular Dynamics Simulations and Continuum Electrostatics Calculations

PubMed Central

Peter, Christine; Hummer, Gerhard

2005-01-01

Narrow hydrophobic regions are a common feature of biological channels, with possible roles in ion-channel gating. We study the principles that govern ion transport through narrow hydrophobic membrane pores by molecular dynamics simulation of model membranes formed of hexagonally packed carbon nanotubes. We focus on the factors that determine the energetics of ion translocation through such nonpolar nanopores and compare the resulting free-energy barriers for pores with different diameters corresponding to the gating regions in closed and open forms of potassium channels. Our model system also allows us to compare the results from molecular dynamics simulations directly to continuum electrostatics calculations. Both simulations and continuum calculations show that subnanometer wide pores pose a huge free-energy barrier for ions, but a small increase in the pore diameter to ∼1 nm nearly eliminates that barrier. We also find that in those wider channels the ion mobility is comparable to that in the bulk phase. By calculating local electrostatic potentials, we show that the long range Coulomb interactions of ions are strongly screened in the wide water-filled channels. Whereas continuum calculations capture the overall energetics reasonably well, the local water structure, which is not accounted for in this model, leads to interesting effects such as the preference of hydrated ions to move along the pore wall rather than through the center of the pore. PMID:16006629

Generation of high charge state metal ion beams by electron cyclotron resonance heating of vacuum arc plasma in cusp trap.

PubMed

Nikolaev, A G; Savkin, K P; Oks, E M; Vizir, A V; Yushkov, G Yu; Vodopyanov, A V; Izotov, I V; Mansfeld, D A

2012-02-01

A method for generating high charge state heavy metal ion beams based on high power microwave heating of vacuum arc plasma confined in a magnetic trap under electron cyclotron resonance conditions has been developed. A feature of the work described here is the use of a cusp magnetic field with inherent "minimum-B" structure as the confinement geometry, as opposed to a simple mirror device as we have reported on previously. The cusp configuration has been successfully used for microwave heating of gas discharge plasma and extraction from the plasma of highly charged, high current, gaseous ion beams. Now we use the trap for heavy metal ion beam generation. Two different approaches were used for injecting the vacuum arc metal plasma into the trap--axial injection from a miniature arc source located on-axis near the microwave window, and radial injection from sources mounted radially at the midplane of the trap. Here, we describe preliminary results of heating vacuum arc plasma in a cusp magnetic trap by pulsed (400 μs) high power (up to 100 kW) microwave radiation at 37.5 GHz for the generation of highly charged heavy metal ion beams.

Towards Non-Equilibrium Dynamics with Trapped Ions

NASA Astrophysics Data System (ADS)

Silbert, Ariel; Jubin, Sierra; Doret, Charlie

2016-05-01

Atomic systems are superbly suited to the study of non-equilibrium dynamics. These systems' exquisite isolation from environmental perturbations leads to long relaxation times that enable exploration of far-from-equilibrium phenomena. One example of particular relevance to experiments in trapped ion quantum information processing, metrology, and precision spectroscopy is the approach to thermal equilibrium of sympathetically cooled linear ion chains. Suitable manipulation of experimental parameters permits exploration of the quantum-to-classical crossover between ballistic transport and diffusive, Fourier's Law conduction, a topic of interest not only to the trapped ion community but also for the development of microelectronic devices and other nanoscale structures. We present progress towards trapping chains of multiple co-trapped calcium isotopes geared towards measuring thermal equilibration and discuss plans for future experiments in non-equilibrium statistical mechanics. This work is supported by Cottrell College Science Award from the Research Corporation for Science Advancement and by Williams College.

Operational Parameters, Considerations, and Design Decisions for Resource-Constrained Ion Trap Mass Spectrometers

NASA Technical Reports Server (NTRS)

Danell, Ryan M.; VanAmerom, Friso H. W.; Pinnick, Veronica; Cotter, Robert J.; Brickerhoff, William; Mahaffy, Paul

2011-01-01

Mass spectrometers are increasingly finding applications in new and unique areas, often in situations where key operational resources (i.e. power, weight and size) are limited. One such example is the Mars Organic Molecule Analyzer (MOMA). This instrument is a joint venture between NASA and the European Space Agency (ESA) to develop an ion trap mass spectrometer for chemical analysis on Mars. The constraints on such an instrument are significant as are the performance requirements. While the ideal operating parameters for an ion trap are generally well characterized, methods to maintain analytical performance with limited power and system weight need to be investigated and tested. Methods Experiments have been performed on two custom ion trap mass spectrometers developed as prototypes for the MOMA instrument. This hardware consists of quadrupole ion trap electrodes that are 70% the size of common commercial instrumentation. The trapping RF voltage is created with a custom tank circuit that can be tuned over a range of RF frequencies and is driven using laboratory supplies and amplifiers. The entire instrument is controlled with custom Lab VIEW software that allows a high degree of flexibility in the definition of the scan function defining the ion trap experiment. Ions are typically generated via an internal electron ionization source, however, a laser desorption source is also in development for analysis of larger intact molecules. Preliminary Data The main goals in this work have been to reduce the power required to generate the radio frequency trapping field used in an ion trap mass spectrometer. Generally minimizing the power will also reduce the volume and mass of the electronics to support the instrument. In order to achieve optimum performance, commercial instruments typically utilize RF frequencies in the 1 MHz range. Without much concern for power usage, they simply generate the voltage required to access the mass range of interest. In order to reduce the required RF voltage (and power), operation of the ion trap at lower RF frequencies has been investigated. Surprisingly, the performance of the instrument has only been slightly degraded at RF frequencies all the way down to 500 kHz. Mass resolution is relatively stable to this point and depending on the resonant ejection point used, the peak intensity is also quite stable. To date only masses up to m/z 200 have been fully investigated, however, additional studies are planned to verify the performance with higher mass ions. The lower frequency and voltage should reduce the pseudo potential well depth, eventually affecting the trapping efficiency of the instrument -- effect that could manifest itself in significantly limiting the mass range of trapped ions. Other methods to reduce the RF power while maintaining analytical performance are also under investigation. This includes ion ejection at lower q(sub z) values to access a given mass with a lower RF voltage. The loss of mass resolution at lower q(sub eject) points has been measured and current work is underway to leverage scan speed and the use of non-linear resonances in order to counter this trend. The overall trap performance under this range of operating conditions will be presented with a goal of identifying what trade-offs are acceptable.

Rydberg Excitation of a Single Trapped Ion.

PubMed

Feldker, T; Bachor, P; Stappel, M; Kolbe, D; Gerritsma, R; Walz, J; Schmidt-Kaler, F

2015-10-23

We demonstrate excitation of a single trapped cold (40)Ca(+) ion to Rydberg levels by laser radiation in the vacuum ultraviolet at a wavelength of 122 nm. Observed resonances are identified as 3d(2)D(3/2) to 51F, 52F and 3d(2)D(5/2) to 64F. We model the line shape and our results imply a large state-dependent coupling to the trapping potential. Rydberg ions are of great interest for future applications in quantum computing and simulation, in which large dipolar interactions are combined with the superb experimental control offered by Paul traps.

Dust Acoustic Solitary Waves in Dusty Plasma with Trapped Electrons Having Different Temperature Nonthermal Ions

NASA Astrophysics Data System (ADS)

Deka, Manoj Kr.

2016-12-01

In this report, a detailed investigation on the study of dust acoustics solitary waves solution with negatively dust charge fluctuation in dusty plasma corresponding to lower and higher temperature nonthermal ions with trapped electrons is presented. We consider temporal variation of dust charge as a source of dissipation term to derive the lower order modified Kadomtsev-Petviashvili equation by using the reductive perturbation technique. Solitary wave solution is obtained with the help of sech method in presence of trapped electrons and low (and high) temperature nonthermal ions. Both nonthermality of ions and trapped state of the electrons are found to have an imperative control on the nonlinear coefficient, dissipative coefficient as well as height of the wave potential.

Towards Laser Cooling Trapped Ions with Telecom Light

NASA Astrophysics Data System (ADS)

Dungan, Kristina; Becker, Patrick; Donoghue, Liz; Liu, Jackie; Olmschenk, Steven

2015-05-01

Quantum information has many potential applications in communication, atomic clocks, and the precision measurement of fundamental constants. Trapped ions are excellent candidates for applications in quantum information because of their isolation from external perturbations, and the precise control afforded by laser cooling and manipulation of the quantum state. For many applications in quantum communication, it would be advantageous to interface ions with telecom light. We present progress towards laser cooling and trapping of doubly-ionized lanthanum, which should require only infrared, telecom-compatible light. Additionally, we present progress on optimization of a second-harmonic generation cavity for laser cooling and trapping barium ions, for future sympathetic cooling experiments. This research is supported by the Army Research Office, Research Corporation for Science Advancement, and Denison University.

Characteristics of low energy ions in the Heavy Ions In Space (HIIS) experiment

NASA Technical Reports Server (NTRS)

Kleis, Thomas; Tylka, Allan J.; Boberg, Paul R.; Adams, James H., Jr.; Beahm, Lorraine P.

1995-01-01

We present preliminary data on heavy ions (Z greater than or equal to 10) detected in the topmost Lexan sheets of the track detector stacks of the Heavy Ions in space (HIIS) experiment (M0001) on LDEF. The energy interval covered by these observations varies with the element, with (for example) Ne observable at 18-100 MeV nuc and Fe at 45-200 MeV/nuc. All of the observed ions are at energies far below the geomagnetic cutoff for fully-ionized particles at the LDEF orbit. Above 50 MeV/nuc (where most of our observed particles are Fe), the ions arrive primarily from the direction of lowest geomagnetic cutoff. This suggests that these particles originate outside the magnetosphere from a source with a steeply-falling spectrum and may therefore be associated with solar energetic particle (SEP) events. Below 50 MeV/nuc, the distribution of arrival directions suggests that most of the observed heavy ions are trapped in the Earth's magnetic field. Preliminary analysis, however, shows that these trapped heavy ions have a very surprising composition: they include not only Ne and Ar, which are expected from the trapping of anomalous cosmic rays (ACR's), but also Mg and Si, which are not part of the anomalous component. Our preliminary analysis shows that trapped heavy ions at 12 less than or equal to Zeta less than or equal to 14 have a steeply-falling spectrum, similar to that reported by the Kiel experiment (exp 1,2,3) on LDEF (M0002) for trapped Ar and Fe at E less than 50 MeV/nuc. The trapped Mg, Si, and Fe may also be associated with SEP events, but the mechanism by which they have appeared to deep in the inner magnetosphere requires further theoretical investigation.

High-Fidelity Preservation of Quantum Information During Trapped-Ion Transport

NASA Astrophysics Data System (ADS)

Kaufmann, Peter; Gloger, Timm F.; Kaufmann, Delia; Johanning, Michael; Wunderlich, Christof

2018-01-01

A promising scheme for building scalable quantum simulators and computers is the synthesis of a scalable system using interconnected subsystems. A prerequisite for this approach is the ability to faithfully transfer quantum information between subsystems. With trapped atomic ions, this can be realized by transporting ions with quantum information encoded into their internal states. Here, we measure with high precision the fidelity of quantum information encoded into hyperfine states of a Yb171 + ion during ion transport in a microstructured Paul trap. Ramsey spectroscopy of the ion's internal state is interleaved with up to 4000 transport operations over a distance of 280 μ m each taking 12.8 μ s . We obtain a state fidelity of 99.9994 (-7+6) % per ion transport.

A multiple-orbit time-of-flight mass spectrometer based on a low energy electrostatic storage ring

NASA Astrophysics Data System (ADS)

Sullivan, M. R.; Spanjers, T. L.; Thorn, P. A.; Reddish, T. J.; Hammond, P.

2012-11-01

The results are presented for an electrostatic storage ring, consisting of two hemispherical deflector analyzers (HDA) connected by two separate sets of cylindrical lenses, used as a time-of-flight mass spectrometer. Based on the results of charged particle simulations and formal matrix model, the Ion Storage Ring is capable of operating with multiple stable orbits, for both single and multiply charged ions simultaneously.

Adsorption of charged protein residues on an inorganic nanosheet: Computer simulation of LDH interaction with ion channel

NASA Astrophysics Data System (ADS)

Tsukanov, Alexey A.; Psakhie, Sergey G.

2016-08-01

Quasi-two-dimensional and hybrid nanomaterials based on layered double hydroxides (LDH), cationic clays, layered oxyhydroxides and hydroxides of metals possess large specific surface area and strong electrostatic properties with permanent or pH-dependent electric charge. Such nanomaterials may impact cellular electrostatics, changing the ion balance, pH and membrane potential. Selective ion adsorption/exchange may alter the transmembrane electrochemical gradient, disrupting potential-dependent cellular processes. Cellular proteins as a rule have charged residues which can be effectively adsorbed on the surface of layered hydroxide based nanomaterials. The aim of this study is to attempt to shed some light on the possibility and mechanisms of protein "adhesion" an LDH nanosheet and to propose a new direction in anticancer medicine, based on physical impact and strong electrostatics. An unbiased molecular dynamics simulation was performed and the combined process free energy estimation (COPFEE) approach was used.

Coarse-graining, Electrostatics and pH effects in phospholipid systems

NASA Astrophysics Data System (ADS)

Travesset, Alex; Vangaveti, Sweta

2010-03-01

We introduce a minimal free energy describing the interaction of charged groups and counterions including both classical electrostatic and specific interactions. The predictions of the model are compared against the standard model for describing ions next to charged interfaces, consisting of Poisson-Boltzmann theory with additional constants describing ion binding, which are specific to the counterion and the interfacial charge (``chemical binding''). It is shown that the ``chemical'' model can be appropriately described by an underlying ``physical'' model over several decades in concentration, but the extracted binding constants are not uniquely defined, as they differ depending on the particular observable quantity being studied. It is also shown that electrostatic correlations for divalent (or higher valence) ions enhance the surface charge by increasing deprotonation, an effect not properly accounted within chemical models. The model is applied to the charged phospholipids phosphatidylserine, Phosphatidc acid and Phosphoinositides and implications for different biological processes are discussed.

Electrostatic lens to focus an ion beam to uniform density

DOEpatents

Johnson, Cleland H.

1977-01-11

A focusing lens for an ion beam having a gaussian or similar density profile is provided. The lens is constructed to provide an inner zero electrostatic field, and an outer electrostatic field such that ions entering this outer field are deflected by an amount that is a function of their distance from the edge of the inner field. The result is a beam that focuses to a uniform density in a manner analogous to that of an optical ring lens. In one embodiment, a conically-shaped network of fine wires is enclosed within a cylindrical anode. The wire net together with the anode produces a voltage field that re-directs the outer particles of the beam while the axial particles pass undeflected through a zero field inside the wire net. The result is a focused beam having a uniform intensity over a given target area and at a given distance from the lens.

Electrostatic Wave Generation and Transverse Ion Acceleration by Alfvenic Wave Components of BBELF Turbulence

NASA Technical Reports Server (NTRS)

Singh, Nagendra; Khazanov, George; Mukhter, Ali

2007-01-01

We present results here from 2.5-D particle-in-cell simulations showing that the electrostatic (ES) components of broadband extremely low frequency (BBELF) waves could possibly be generated by cross-field plasma instabilities driven by the relative drifts between the heavy and light ion species in the electromagnetic (EM) Alfvenic component of the BBELF waves in a multi-ion plasma. The ES components consist of ion cyclotron as well as lower hybrid modes. We also demonstrate that the ES wave generation is directly involved in the transverse acceleration of ions (TAI) as commonly measured with the BBELF wave events. The heating is affected by ion cyclotron resonance in the cyclotron modes and Landau resonance in the lower hybrid waves. In the simulation we drive the plasma by the transverse electric field, E(sub y), of the EM waves; the frequency of E(sub y), omega(sub d), is varied from a frequency below the heavy ion cyclotron frequency, OMEGA(sub h), to below the light ion cyclotron frequency, OMEGA(sub i). We have also performed simulations for E(sub y) having a continuous spectrum given by a power law, namely, |Ey| approx. omega(sub d) (exp -alpha), where the exponent alpha = _, 1, and 2 in three different simulations. The driving electric field generates polarization and ExB drifts of the ions and electrons. When the interspecies relative drifts are sufficiently large, they drive electrostatic waves, which cause perpendicular heating of both light and heavy ions. The transverse ion heating found here is discussed in relation to observations from Cluster, FAST and Freja.

DC Potentials Applied to an End-cap Electrode of a 3-D Ion Trap for Enhanced MSn Functionality

PubMed Central

Prentice, Boone M.; Xu, Wei; Ouyang, Zheng; McLuckey, Scott A.

2010-01-01

The effects of the application of various DC magnitudes and polarities to an end-cap of a 3-D quadrupole ion trap throughout a mass spectrometry experiment were investigated. Application of a monopolar DC field was achieved by applying a DC potential to the exit end-cap electrode, while maintaining the entrance end-cap electrode at ground potential. Control over the monopolar DC magnitude and polarity during time periods associated with ion accumulation, mass analysis, ion isolation, ion/ion reaction, and ion activation can have various desirable effects. Included amongst these are increased ion capture efficiency, increased ion ejection efficiency during mass analysis, effective isolation of ions using lower AC resonance ejection amplitudes, improved temporal control of the overlap of oppositely charged ion populations, and the performance of “broad-band” collision induced dissociation (CID). These results suggest general means to improve the performance of the 3-D ion trap in a variety of mass spectrometry and tandem mass spectrometry experiments. PMID:21927573

Ion acoustic wave assisted laser beat wave terahertz generation in a plasma channel

NASA Astrophysics Data System (ADS)

Tyagi, Yachna; Tripathi, Deepak; Walia, Keshav; Garg, Deepak

2018-04-01

Resonant excitation of terahertz (THz) radiation by non-linear mixing of two lasers in the presence of an electrostatic wave is investigated. The electrostatic wave assists in k matching and contributes to non-linear coupling. In this plasma channel, the electron plasma frequency becomes minimum on the axis. The beat frequency ponderomotive force imparts an oscillating velocity to the electrons. In the presence of an ion-acoustic wave, density perturbation due to the ion-acoustic wave couples with the oscillating velocity of the electrons and give rise to non-linear current that gives rise to an ion-acoustic wave frequency assisted THz radiation field. The normalized field amplitude of ion acoustic wave assisted THz varies inversely for ω/ωp . The field amplitude of ion acoustic wave assisted THz decreases as ω/ωp increases.

Stimulated Brillouin Scatter in a Magnetized Ionospheric Plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bernhardt, P. A.; Selcher, C. A.; Lehmberg, R. H.

2010-04-23

High power electromagnetic waves transmitted from the HAARP facility in Alaska can excite low-frequency electrostatic waves by magnetized stimulated Brillouin scatter. Either an ion-acoustic wave with a frequency less than the ion cyclotron frequency (f{sub CI}) or an electrostatic ion cyclotron (EIC) wave just above f{sub CI} can be produced. The coupled equations describing the magnetized stimulated Brillouin scatter instability show that the production of both ion-acoustic and EIC waves is strongly influenced by the wave propagation relative to the background magnetic field. Experimental observations of stimulated electromagnetic emissions using the HAARP transmitter have confirmed that only ion-acoustic waves aremore » excited for propagation along the magnetic zenith and that EIC waves can only be detected with oblique propagation angles. The ion composition can be obtained from the measured EIC frequency.« less

Electrostatic shock structures in dissipative multi-ion dusty plasmas

NASA Astrophysics Data System (ADS)

Elkamash, I. S.; Kourakis, I.

2018-06-01

A comprehensive analytical model is introduced for shock excitations in dusty bi-ion plasma mixtures, taking into account collisionality and kinematic (fluid) viscosity. A multicomponent plasma configuration is considered, consisting of positive ions, negative ions, electrons, and a massive charged component in the background (dust). The ionic dynamical scale is focused upon; thus, electrons are assumed to be thermalized, while the dust is stationary. A dissipative hybrid Korteweg-de Vries/Burgers equation is derived. An analytical solution is obtained, in the form of a shock structure (a step-shaped function for the electrostatic potential, or an electric field pulse) whose maximum amplitude in the far downstream region decays in time. The effect of relevant plasma configuration parameters, in addition to dissipation, is investigated. Our work extends earlier studies of ion-acoustic type shock waves in pure (two-component) bi-ion plasma mixtures.

New facility for ion beam materials characterization and modification at Los Alamos

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tesmer, J.R.; Maggiore, C.J.; Parkin, D.M.

1988-01-01

The Ion Beam Materials Laboratory (IBML) is a new Los Alamos laboratory devoted to the characterization and modification of the near surfaces of materials. The primary instruments of the IBML are a tandem electrostatic accelerator, a National Electrostatics Corp. Model 9SDH, coupled with a Varian CF-3000 ion implanter. The unique organizational structure of the IBML as well as the operational characteristics of the 9SDH (after approximately 3000 h of operation) and the laboratories' research capabilities will be discussed. Examples of current research results will also be presented. 5 refs., 2 figs.

High-Energy Electron Shell in ECR Ion Source:

NASA Astrophysics Data System (ADS)

Niimura, M. G.; Goto, A.; Yano, Y.

1997-05-01

As an injector of cyclotrons and RFQ linacs, ECR ion source (ECRIS) is expected to deliver highly charged ions (HCI) at high beam-current (HBC). Injections of light gases and supplementary electrons have been employed for enhancement of HCI and HBC, respectively. Further amelioration of the performance may be feasible by investigating the hot-electron ring inside an ECRIS. Its existence has been granted because of the MeV of Te observable via X-ray diagnostics. However, its location, acceleration mechanism, and effects on the performance are not well known.We found them by deriving the radially negative potential distribution for an ECRIS from measured endloss-current data. It was evidenced from a hole-burning on the parabolic potential profile (by uniformly distributed warm-electron space charges of 9.5x10^5cm-3) and from a local minimum of the electrostatically-trapped ion distribution. A high-energy electron shell (HEES) was located right on the ECR-radius of 6 cm with shell-halfwidth of 1 cm. Such a thin shell around core plasma can only be generated by the Sadeev-Shapiro or v_phxBz acceleration mechanism that can raise Te up to a relativistic value. Here, v_ph is the phase velocity of ES Bernstein waves propagating backwards against incident microwave and Bz the axial mirror magnetic field. The HEES carries diamagnetic current which reduces the core magnetic pressure, thereby stabilizing the ECR surface against driftwave instabilities similarly to gas-mixing.

Stress influenced trapping processes in Si based multi-quantum well structures and heavy ions implanted Si

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ciurea, Magdalena Lidia, E-mail: ciurea@infim.ro; Lazanu, Sorina, E-mail: ciurea@infim.ro

2014-10-06

Multi-quantum well structures and Si wafers implanted with heavy iodine and bismuth ions are studied in order to evaluate the influence of stress on the parameters of trapping centers. The experimental method of thermostimullatedcurrents without applied bias is used, and the trapping centers are filled by illumination. By modeling the discharge curves, we found in multilayered structures the parameters of both 'normal' traps and 'stress-induced' ones, the last having a Gaussian-shaped temperature dependence of the cross section. The stress field due to the presence of stopped heavy ions implanted into Si was modeled by a permanent electric field. The increasemore » of the strain from the neighborhood of I ions to the neighborhood of Bi ions produces the broadening of some energy levels and also a temperature dependence of the cross sections for all levels.« less

Stress influenced trapping processes in Si based multi-quantum well structures and heavy ions implanted Si

NASA Astrophysics Data System (ADS)

Ciurea, Magdalena Lidia; Lazanu, Sorina

2014-10-01

Multi-quantum well structures and Si wafers implanted with heavy iodine and bismuth ions are studied in order to evaluate the influence of stress on the parameters of trapping centers. The experimental method of thermostimullatedcurrents without applied bias is used, and the trapping centers are filled by illumination. By modeling the discharge curves, we found in multilayered structures the parameters of both 'normal' traps and 'stress-induced' ones, the last having a Gaussian-shaped temperature dependence of the cross section. The stress field due to the presence of stopped heavy ions implanted into Si was modeled by a permanent electric field. The increase of the strain from the neighborhood of I ions to the neighborhood of Bi ions produces the broadening of some energy levels and also a temperature dependence of the cross sections for all levels.

A trapped mercury 199 ion frequency standard

NASA Technical Reports Server (NTRS)

Cutler, L. S.; Giffard, R. P.; Mcguire, M. D.

1982-01-01

Mercury 199 ions confined in an RF quadrupole trap and optically pumped by mercury 202 ion resonance light are investigated as the basis for a high performance frequency standard with commercial possibilities. Results achieved and estimates of the potential performance of such a standard are given.

Photoionization of the Buckminsterfullerene Cation.

PubMed

Douix, Suzie; Duflot, Denis; Cubaynes, Denis; Bizau, Jean-Marc; Giuliani, Alexandre

2017-01-05

Photoionization of a buckminsterfullerene ion is investigated using an ion trap and a merged beam setup coupled to synchrotron radiation beamlines and compared to theoretical calculations. Absolute measurements derived from the ion trap experiment allow discrepancies concerning the photoionization cross section of C 60 + to be solved.

Instability due to trapped electrons in magnetized multi-ion dusty plasmas

NASA Astrophysics Data System (ADS)

Haider, M. M.; Ferdous, T.; Duha, S. S.

2015-05-01

An attempt has been made to find out the effects of trapped electrons in dust-ion-acoustic solitary waves in magnetized multi-ion plasmas, as in most space plasmas, the hot electrons follow the trapped/vortex-like distribution. To do so, we have derived modified Zakharov-Kuznetsov equation using reductive perturbation method and its solution. A small- perturbation technique was employed to find out the instability criterion and growth rate of such a wave.

Experimental Observation of the Effects of Translational and Rotational Electrode Misalignment on a Planar Linear Ion Trap Mass Spectrometer

NASA Astrophysics Data System (ADS)

Tian, Yuan; Decker, Trevor K.; McClellan, Joshua S.; Wu, Qinghao; De la Cruz, Abraham; Hawkins, Aaron R.; Austin, Daniel E.

2018-04-01

The performance of miniaturized ion trap mass analyzers is limited, in part, by the accuracy with which electrodes can be fabricated and positioned relative to each other. Alignment of plates in a two-plate planar LIT is ideal to characterize misalignment effects, as it represents the simplest possible case, having only six degrees of freedom (DOF) (three translational and three rotational). High-precision motorized actuators were used to vary the alignment between the two ion trap plates in five DOFs—x, y, z, pitch, and yaw. A comparison between the experiment and previous simulations shows reasonable agreement. Pitch, or the degree to which the plates are parallel along the axial direction, has the largest and sharpest impact to resolving power, with resolving power dropping noticeably with pitch misalignment of a fraction of a degree. Lateral displacement (x) and yaw (rotation of one plate, but plates remain parallel) both have a strong impact on ion ejection efficiency, but little effect on resolving power. The effects of plate spacing (y-displacement) on both resolving power and ion ejection efficiency are attributable to higher-order terms in the trapping field. Varying the DC (axial) trapping potential can elucidate the effects where more misalignments in more than one DOF affect performance. Implications of these results for miniaturized ion traps are discussed. [Figure not available: see fulltext.

Nonlinear regime of electrostatic waves propagation in presence of electron-electron collisions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pezzi, Oreste; Valentini, Francesco; Veltri, Pierluigi

2015-04-15

The effects are presented of including electron-electron collisions in self-consistent Eulerian simulations of electrostatic wave propagation in nonlinear regime. The electron-electron collisions are approximately modeled through the full three-dimensional Dougherty collisional operator [J. P. Dougherty, Phys. Fluids 7, 1788 (1964)]; this allows the elimination of unphysical byproducts due to reduced dimensionality in velocity space. The effects of non-zero collisionality are discussed in the nonlinear regime of the symmetric bump-on-tail instability and in the propagation of the so-called kinetic electrostatic electron nonlinear (KEEN) waves [T. W. Johnston et al., Phys. Plasmas 16, 042105 (2009)]. For both cases, it is shown howmore » collisions work to destroy the phase-space structures created by particle trapping effects and to damp the wave amplitude, as the system returns to the thermal equilibrium. In particular, for the case of the KEEN waves, once collisions have smoothed out the trapped particle population which sustains the KEEN fluctuations, additional oscillations at the Langmuir frequency are observed on the fundamental electric field spectral component, whose amplitude decays in time at the usual collisionless linear Landau damping rate.« less

Measurement System of Surface Electrostatic Potential on Insulation Board in Vacuum and its Application

NASA Astrophysics Data System (ADS)

Morita, Hiroshi; Hatanaka, Ayumu; Yokosuka, Toshiyuki; Seki, Yoshitaka; Tsumuraya, Yoshiaki; Doi, Motomichi

The measurement system of the surface electrostatic potential on a solid insulation board in vacuum has been developed. We used this system to measure the electrostatic potential distribution of the surface of a borosilicate glass plate applied a high voltage. A local increase in the electric field was observed. It is considered that this phenomenon is caused by a positive electrostatic charge generated by a secondary emission of field emission electrons from an electrode. On the other hand, a local increase in the electric field was not observed on a glass plate coated with silica particles and a glass plate roughened by sandblast. We reasoned that this could be because the electrons were trapped by the roughness of the surface. It is considered that these phenomena make many types of equipment using the vacuum insulation more reliable.

Compression Ratio Ion Mobility Programming (CRIMP) Accumulation and Compression of Billions of Ions for Ion Mobility-Mass Spectrometry Using Traveling Waves in Structures for Lossless Ion Manipulations (SLIM)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Deng, Liulin; Garimella, Sandilya V. B.; Hamid, Ahmed M.

We report on the implementation of a traveling wave (TW) based compression ratio ion mobility programming (CRIMP) approach within Structures for Lossless Ion Manipulations (SLIM) that enables both greatly enlarged trapped ion charge capacities and also their subsequent efficient compression for use in ion mobility (IM) separations. Ion accumulation is conducted in a long serpentine path TW SLIM region after which CRIMP allows the large ion populations to be ‘squeezed’. The compression process occurs at an interface between two SLIM regions, one operating conventionally and the second having an intermittently pausing or ‘stuttering’ TW, allowing the contents of multiple binsmore » of ions from the first region to be merged into a single bin in the second region. In this initial work stationary voltages in the second region were used to block ions from exiting the first (trapping) region, and the resumption of TWs in the second region allows ions to exit, and the population to also be compressed if CRIMP is applied. In our initial evaluation we show that the number of charges trapped for a 40 s accumulation period was ~5×109, more than two orders of magnitude greater than the previously reported charge capacity using an ion funnel trap. We also show that over 1×109 ions can be accumulated with high efficiency in the present device, and that the extent of subsequent compression is only limited by the space charge capacity of the trapping region. Lower compression ratios allow increased IM peak heights without significant loss of signal, while excessively large compression ratios can lead to ion losses and other artifacts. Importantly, we show that extended ion accumulation in conjunction with CRIMP and multiple passes provides the basis for a highly desirable combination of ultra-high sensitivity and ultra-high resolution IM separations using SLIM.« less

Planetary exploration with electrically propelled vehicles.

NASA Technical Reports Server (NTRS)

Stuhlinger, E.

1972-01-01

The characteristics of propulsion systems required for carrying out flight missions within the solar system, as desired by planetary physicists and astronomers, are reviewed. It is shown that an encouraging answer to these requirements is available in the form of electrostatic or ion propulsion systems. The design and performance characteristics of an electrostatic thrustor employing an ion source, accelerating electrode, beam neutralizer, and power source are discussed, together with those of the Kaufmann engine (electrostatic thrustor employing bombardment type ionization). More demanding missions which will become feasible with the advent of nuclear-electric power sources (such as the incore thermionic reactor) may include close orbiters around all the planets, and asteroid and cometary missions.

A highly miniaturized vacuum package for a trapped ion atomic clock

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schwindt, Peter D. D., E-mail: pschwin@sandia.gov; Jau, Yuan-Yu; Partner, Heather

2016-05-15

We report on the development of a highly miniaturized vacuum package for use in an atomic clock utilizing trapped ytterbium-171 ions. The vacuum package is approximately 1 cm{sup 3} in size and contains a linear quadrupole RF Paul ion trap, miniature neutral Yb sources, and a non-evaporable getter pump. We describe the fabrication process for making the Yb sources and assembling the vacuum package. To prepare the vacuum package for ion trapping, it was evacuated, baked at a high temperature, and then back filled with a helium buffer gas. Once appropriate vacuum conditions were achieved in the package, it wasmore » sealed with a copper pinch-off and was subsequently pumped only by the non-evaporable getter. We demonstrated ion trapping in this vacuum package and the operation of an atomic clock, stabilizing a local oscillator to the 12.6 GHz hyperfine transition of {sup 171}Y b{sup +}. The fractional frequency stability of the clock was measured to be 2 × 10{sup −11}/τ{sup 1/2}.« less

Ion-acoustic and electron-acoustic type nonlinear waves in dusty plasmas

NASA Astrophysics Data System (ADS)

Volosevich, A.-V.; Meister, C.-V.

2003-04-01

In the present work, two three-dimensional nonlinear theoretical models of electrostatic solitary waves are investigated within the frame of magnetohydrodynamics. Both times, a multi-component plasma is considered, which consists of hot electrons with a rather flexible distribution function, hot ions with Boltzmann-type distribution, and (negatively as well as positively charged) dust. Additionally, cold ion beams are taken into account in the model to study ion-acoustic structures (IAS), and cold electron beams are included into the model to investigate electron-acoustic structures (EAS). The numerical results of the considered theoretical models allow to make the following conclusions: 1) Electrostatic structures with negative potential (of rarefaction type) are formed both in the IAS model and in the EAS model, but structures with negative potential (of compressional type) are formed in the IAS model only. 2) The intervals of various plasma parameters (velocities of ion and electron beams, temperatures, densities of the plasma components, ions' masses), for which the existence of IAS and EAS solitary waves and structures is possible, are calculated. 3) Further, the parameters of the electrostatic structures (wave amplitudes, scales along and perpendicular to the magnetic field, velocities) are estimated. 4) The application of the present numerical simulation for multi-component plasmas to various astrophysical systems under different physical conditions is discussed.

Generation and Micro-scale Effects of Electrostatic Waves in an Oblique Shock

NASA Astrophysics Data System (ADS)

Goodrich, K.; Ergun, R.; Schwartz, S. J.; Newman, D.; Johlander, A.; Argall, M. R.; Wilder, F. D.; Torbert, R. B.; Khotyaintsev, Y. V.; Lindqvist, P. A.; Strangeway, R. J.; Russell, C. T.; Giles, B. L.; Gershman, D. J.; Burch, J. L.

2017-12-01

We present an analysis of large amplitude (>100 mV/m), high frequency (≤1 kHz), electrostatic waves observed by MMS during an oblique bow shock crossing event. The observed waves primarily consist of electrostatic solitary waves (ESWs) and oblique ion plasma waves (IPWs). ESWs typically include nonlinear structures such as double layers, ion phase-space holes, and electron phase-space holes. Oblique IPWs are observed to be similar to ion acoustic waves, but can propagate up to 70° from the ambient magnetic field direction. Both wave-modes, particularly IPWs, are observed to have very short wavelengths ( 100 m) and are highly localized. While such wave-modes have been previously observed in the terrestrial bow shock, instrumental constraints have limited detailed insight into their generation and their effect on their plasma shock environment. Analysis of this oblique shock event shows evidence that ESWs and oblique IPWs can be generated through field-aligned currents associated with magnetic turbulence and through a counterstreaming ion instability respectively. We also present evidence that this wave activity can facilitate momentum exchange between ion populations, resulting in deceleration of incoming solar wind, and localized electron heating.

Stability of Electrons in the Virtual Cathode Region of an IEC

NASA Astrophysics Data System (ADS)

Kim, Hyng-Jin; Miley, George; Momota, Hiromu

2003-04-01

In the Inertial Electrostatic Confinement (IEC) device, electrons are confined inside a virtual anode that in turn confines ions. Prior stability studies [1, 2] have considered systems in which one species is electrostatically confined by the other, and either or both species are out of local thermal equilibrium. In the present research, electron stability in the virtual cathode region of an ion injected IEC is being studied. The ion density in an IEC is non-uniform due to the radial electrostatic potential, and increases toward the center region. The potential near the virtual cathode is assumed to have a parabolic shape and is determined assuming that the net space charge density is constant in that region. The corresponding ion distribution function is assumed to have the form f = C [sigma] (H W) /L^0.5 and the electron response is taken to be diabatic. Then using a variational principle after linearizing the hydrodynamic equations, stability properties of the electron layer are determined. Results will be presented as a function of injected ion/electron current ratios. 1. L. Chacon and D. C. Barnes, Phys. Plasma 7, 4774 (2000). 2. D. C. Barnes, L. Chacon, and J. M. Finn, Phys. Plasmas 9, 4448 (2002).

The thermally stimulated discharge of ion-irradiated oxide films

NASA Astrophysics Data System (ADS)

Wang, Qiuru; Zeng, Huizhong; Zhang, Wanli

2018-01-01

The ion irradiation technique is utilized to modify the surface structure of amorphous insulating oxide films. While introducing defects, a number of surface charges are injected into the films and captured in the traps during ion irradiation. The variation of surface morphology and the enhancement of emission spectrum corresponding to vacancy defects are respectively verified by atomic force microscopy and photoluminescence measurements. The surface charges trapped in the shallow traps are easy to release caused by thermal excitation, and discharge is observed during heating. Based on the thermally stimulated discharge measurements, the trap parameters of oxide films, such as activation energy and relaxation time, are calculated from experimental data.

Axial motion of collector plasma in a relativistic backward wave oscillator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xiao, Renzhen; Chen, Changhua; Deng, Yuqun

2016-06-15

In this paper, it is proposed that plasma formed at the collector may drift back to the cathode and cause pulse shortening of the relativistic backward wave oscillator. Theoretical analysis shows that the axial drift velocity of plasma ions can be up to 5 mm/ns due to the presence of space charge potential provided by an intense relativistic electron beam. Particle-in-cell simulations indicate that the plasma electrons are initially trapped around the collector surface. With the accumulation of the plasma ions, a large electrostatic field forms and drives the plasma electrons to overcome the space charge potential and enter the beam-wavemore » interaction region along the magnetic field lines. As a result, the beam current modulation is disturbed and the output microwave power falls rapidly. The plasma ions move in the beam-wave interaction region with an average axial velocity of 5–8 mm/ns. After the plasma ions reach the diode region, the emitted current at the cathode rises due to the charge neutralizations by the ions. The impedance collapse leads to further decrease of the microwave power. In experiments, when the diode voltage and beam current were 850 kV and 9.2 kA, and the collector radius was 2.15 cm, the output microwave power was 2.4 GW with a pulse width of less than 20 ns. The ion drift velocity was estimated to be about 5 mm/ns. After an improved collector with 3.35 cm radius was adopted, the pulse width was prolonged to more than 30 ns.« less

Scalable Multiplexed Ion Trap (SMIT) Program

DTIC Science & Technology

2010-12-08

an integrated micromirror . The symmetric cross and the mirror trap had a number of complex design features. Both traps shaped the electrodes in...genetic algorithm. 6. Integrated micromirror . The Gen II linear trap (as well as the linear sections of the mirror and the cross) had a number of new...conventional imaging system constructed by off-the-shelf optical components and a micromirror located very close to the ion. A large fraction of photons

Scalable ion-photon quantum interface based on integrated diffractive mirrors

NASA Astrophysics Data System (ADS)

Ghadimi, Moji; Blūms, Valdis; Norton, Benjamin G.; Fisher, Paul M.; Connell, Steven C.; Amini, Jason M.; Volin, Curtis; Hayden, Harley; Pai, Chien-Shing; Kielpinski, David; Lobino, Mirko; Streed, Erik W.

2017-12-01

Quantum networking links quantum processors through remote entanglement for distributed quantum information processing and secure long-range communication. Trapped ions are a leading quantum information processing platform, having demonstrated universal small-scale processors and roadmaps for large-scale implementation. Overall rates of ion-photon entanglement generation, essential for remote trapped ion entanglement, are limited by coupling efficiency into single mode fibers and scaling to many ions. Here, we show a microfabricated trap with integrated diffractive mirrors that couples 4.1(6)% of the fluorescence from a 174Yb+ ion into a single mode fiber, nearly triple the demonstrated bulk optics efficiency. The integrated optic collects 5.8(8)% of the π transition fluorescence, images the ion with sub-wavelength resolution, and couples 71(5)% of the collected light into the fiber. Our technology is suitable for entangling multiple ions in parallel and overcomes mode quality limitations of existing integrated optical interconnects.

All-optical atom trap as a target for MOTRIMS-like collision experiments

NASA Astrophysics Data System (ADS)

Sharma, S.; Acharya, B. P.; De Silva, A. H. N. C.; Parris, N. W.; Ramsey, B. J.; Romans, K. L.; Dorn, A.; de Jesus, V. L. B.; Fischer, D.

2018-04-01

Momentum-resolved scattering experiments with laser-cooled atomic targets have been performed since almost two decades with magneto-optical trap recoil ion momentum spectroscopy (MOTRIMS) setups. Compared to experiments with gas-jet targets, MOTRIMS features significantly lower target temperatures allowing for an excellent recoil ion momentum resolution. However, the coincident and momentum-resolved detection of electrons was long rendered impossible due to incompatible magnetic field requirements. Here we report on an experimental approach which is based on an all-optical 6Li atom trap that—in contrast to magneto-optical traps—does not require magnetic field gradients in the trapping region. Atom temperatures of about 2 mK and number densities up to 109 cm-3 make this trap ideally suited for momentum-resolved electron-ion coincidence experiments. The overall configuration of the trap is very similar to conventional magneto-optical traps. It mainly requires small modifications of laser beam geometries and polarization which makes it easily implementable in other existing MOTRIMS experiments.

A Quantum Non-Demolition Parity measurement in a mixed-species trapped-ion quantum processor

NASA Astrophysics Data System (ADS)

Marinelli, Matteo; Negnevitsky, Vlad; Lo, Hsiang-Yu; Flühmann, Christa; Mehta, Karan; Home, Jonathan

2017-04-01

Quantum non-demolition measurements of multi-qubit systems are an important tool in quantum information processing, in particular for syndrome extraction in quantum error correction. We have recently demonstrated a protocol for quantum non-demolition measurement of the parity of two beryllium ions by detection of a co-trapped calcium ion. The measurement requires a sequence of quantum gates between the three ions, using mixed-species gates between beryllium hyperfine qubits and a calcium optical qubit. Our work takes place in a multi-zone segmented trap setup in which we have demonstrated high fidelity control of both species and multi-well ion shuttling. The advantage of using two species of ion is that we can individually manipulate and read out the state of each ion species without disturbing the internal state of the other. The methods demonstrated here can be used for quantum error correcting codes as well as quantum metrology and are key ingredients for realizing a hybrid universal quantum computer based on trapped ions. Mixed-species control may also enable the investigation of new avenues in quantum simulation and quantum state control. left the group and working in a company now.

Asymmetric ion trap

DOEpatents

Barlow, Stephan E.; Alexander, Michael L.; Follansbee, James C.

1997-01-01

An ion trap having two end cap electrodes disposed asymmetrically about a center of a ring electrode. The inner surface of the end cap electrodes are conformed to an asymmetric pair of equipotential lines of the harmonic formed by the application of voltages to the electrodes. The asymmetry of the end cap electrodes allows ejection of charged species through the closer of the two electrodes which in turn allows for simultaneously detecting anions and cations expelled from the ion trap through the use of two detectors charged with opposite polarity.

Mathematical Modeling of Resonant Processes in Confined Geometry of Atomic and Atom-Ion Traps

NASA Astrophysics Data System (ADS)

Melezhik, Vladimir S.

2018-02-01

We discuss computational aspects of the developed mathematical models for resonant processes in confined geometry of atomic and atom-ion traps. The main attention is paid to formulation in the nondirect product discrete-variable representation (npDVR) of the multichannel scattering problem with nonseparable angular part in confining traps as the boundary-value problem. Computational efficiency of this approach is demonstrated in application to atomic and atom-ion confinement-induced resonances we predicted recently.

Magnetic coherent population trapping in a single ion

NASA Astrophysics Data System (ADS)

Das, S.; Liu, P.; Grémaud, B.; Mukherjee, M.

2018-03-01

Magnetically induced coherent population trapping has been studied in a single trapped laser cooled ion. The magnetic-field-dependent narrow spectral feature is found to be a useful tool in determining the null point of magnetic field at the ion position. In particular, we use a double Λ scheme that allows us to measure the null magnetic-field point limited by the detector shot noise. We analyzed the system theoretically and found certain long-lived bright states as the dark state is generated under steady-state condition.

Electrostatic coupling of ion pumps.

PubMed

Nieto-Frausto, J; Lüger, P; Apell, H J

1992-01-01

In this paper the electrostatic interactions between membrane-embedded ion-pumps and their consequences for the kinetics of pump-mediated transport processes have been examined. We show that the time course of an intrinsically monomolecular transport reaction can become distinctly nonexponential, if the reaction is associated with charge translocation and takes place in an aggregate of pump molecules. First we consider the electrostatic coupling of a single dimer of ion-pumps embedded in the membrane. Then we apply the treatment to the kinetic analysis of light-driven proton transport by bacteriorhodopsin which forms two-dimensional hexagonal lattices. Finally, for the case of nonordered molecules, we also consider a model in which the pumps are randomly distributed over the nodes of a lattice. Here the average distance is equal to that deduced experimentally and the elemental size of the lattice is the effective diameter of one single pump. This latter model is applied to an aggregate of membrane-embedded Na, K- and Ca-pumps. In all these cases the electrostatic potential considered is the exact solution calculated from the method of electrical images for a plane membrane of finite thickness immersed in an infinite aqueous solution environment. The distributions of charges (ions or charged binding sites) are considered homogeneous or discrete in the membrane and/or in the external solution. In the case of discrete distributions we compare the results from a mean field approximation and a stochastic simulation.

Electrostatic ``bounce'' instability in a magnetotail configuration

NASA Astrophysics Data System (ADS)

Fruit, G.; Louarn, P.; Tur, A.

2013-02-01

To understand the possible destabilization of two-dimensional current sheets, a kinetic model is proposed to describe the resonant interaction between electrostatic modes and trapped particles that bounce within the sheet. This work follows the initial investigation by Tur et al. [Phys. Plasmas 17, 102905 (2010)] that is revised and extended. Using a quasi-parabolic equilibrium state, the linearized gyro-kinetic Vlasov equation is solved for electrostatic fluctuations with period of the order of the electron bounce period. Using an appropriated Fourier expansion of the particle motion along the magnetic field, the complete time integration of the non-local perturbed distribution functions is performed. The dispersion relation for electrostatic modes is then obtained through the quasineutrality condition. It is found that strongly unstable electrostatic modes may develop provided that the current sheet is moderately stretched and, more important, that the proportion of passing particle remains small (less than typically 10%). This strong but finely tuned instability may offer opportunities to explain features of magnetospheric substorms.

Additional application of the NASCAP code. Volume 2: SEPS, ion thruster neutralization and electrostatic antenna model

NASA Technical Reports Server (NTRS)

Katz, I.; Cassidy, J. J.; Mandell, M. J.; Parks, D. E.; Schnuelle, G. W.; Stannard, P. R.; Steen, P. G.

1981-01-01

The interactions of spacecraft systems with the surrounding plasma environment were studied analytically for three cases of current interest: calculating the impact of spacecraft generated plasmas on the main power system of a baseline solar electric propulsion stage (SEPS), modeling the physics of the neutralization of an ion thruster beam by a plasma bridge, and examining the physical and electrical effects of orbital ambient plasmas on the operation of an electrostatically controlled membrane mirror. In order to perform these studies, the NASA charging analyzer program (NASCAP) was used as well as several other computer models and analytical estimates. The main result of the SEPS study was to show how charge exchange ion expansion can create a conducting channel between the thrusters and the solar arrays. A fluid-like model was able to predict plasma potentials and temperatures measured near the main beam of an ion thruster and in the vicinity of a hollow cathode neutralizer. Power losses due to plasma currents were shown to be substantial for several proposed electrostatic antenna designs.

Anomalous momentum and energy transfer rates for electrostatic ion-cyclotron turbulence in downward auroral-current regions of the Earth's magnetosphere. III

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jasperse, John R.; Basu, Bamandas; Lund, Eric J.

2010-06-15

Recently, a new multimoment fluid theory was developed for inhomogeneous, nonuniformly magnetized plasma in the guiding-center and gyrotropic approximation that includes the effect of electrostatic, turbulent, wave-particle interactions (see Jasperse et al. [Phys. Plasmas 13, 072903 (2006); ibid.13, 112902 (2006)]). In the present paper, which is intended as a sequel, it is concluded from FAST satellite data that the electrostatic ion-cyclotron turbulence that appears is due to the operation of an electron, bump-on-tail-driven ion-cyclotron instability for downward currents in the long-range potential region of the Earth's magnetosphere. Approximate closed-form expressions for the anomalous momentum and energy transfer rates for themore » ion-cyclotron turbulence are obtained. The turbulent, inhomogeneous, nonuniformly magnetized, multimoment fluid theory given above, in the limit of a turbulent, homogeneous, uniformly magnetized, quasisteady plasma, yields the well-known formula for the anomalous resistivity given by Gary and Paul [Phys. Rev. Lett. 26, 1097 (1971)] and Tange and Ichimaru [J. Phys. Soc. Jpn. 36, 1437 (1974)].« less

Electron spin resonance from NV centers in diamonds levitating in an ion trap

NASA Astrophysics Data System (ADS)

Delord, T.; Nicolas, L.; Schwab, L.; Hétet, G.

2017-03-01

We report observations of the electron spin resonance (ESR) of nitrogen vacancy centers in diamonds that are levitating in an ion trap. Using a needle Paul trap operating under ambient conditions, we demonstrate efficient microwave driving of the electronic spin and show that the spin properties of deposited diamond particles measured by the ESR are retained in the Paul trap. We also exploit the ESR signal to show angle stability of single trapped mono-crystals, a necessary step towards spin-controlled levitating macroscopic objects.

Integrated fiber-mirror ion trap for strong ion-cavity coupling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brandstätter, B., E-mail: birgit.brandstaetter@uibk.ac.at; Schüppert, K.; Casabone, B.

2013-12-15

We present and characterize fiber mirrors and a miniaturized ion-trap design developed to integrate a fiber-based Fabry-Perot cavity (FFPC) with a linear Paul trap for use in cavity-QED experiments with trapped ions. Our fiber-mirror fabrication process not only enables the construction of FFPCs with small mode volumes, but also allows us to minimize the influence of the dielectric fiber mirrors on the trapped-ion pseudopotential. We discuss the effect of clipping losses for long FFPCs and the effect of angular and lateral displacements on the coupling efficiencies between cavity and fiber. Optical profilometry allows us to determine the radii of curvaturemore » and ellipticities of the fiber mirrors. From finesse measurements, we infer a single-atom cooperativity of up to 12 for FFPCs longer than 200 μm in length; comparison to cavities constructed with reference substrate mirrors produced in the same coating run indicates that our FFPCs have similar scattering losses. We characterize the birefringence of our fiber mirrors, finding that careful fiber-mirror selection enables us to construct FFPCs with degenerate polarization modes. As FFPCs are novel devices, we describe procedures developed for handling, aligning, and cleaning them. We discuss experiments to anneal fiber mirrors and explore the influence of the atmosphere under which annealing occurs on coating losses, finding that annealing under vacuum increases the losses for our reference substrate mirrors. X-ray photoelectron spectroscopy measurements indicate that these losses may be attributable to oxygen depletion in the mirror coating. Special design considerations enable us to introduce a FFPC into a trapped ion setup. Our unique linear Paul trap design provides clearance for such a cavity and is miniaturized to shield trapped ions from the dielectric fiber mirrors. We numerically calculate the trap potential in the absence of fibers. In the experiment additional electrodes can be used to compensate distortions of the potential due to the fibers. Home-built fiber feedthroughs connect the FFPC to external optics, and an integrated nanopositioning system affords the possibility of retracting or realigning the cavity without breaking vacuum.« less

New apparatus of single particle trap system for aerosol visualization

NASA Astrophysics Data System (ADS)

Higashi, Hidenori; Fujioka, Tomomi; Endo, Tetsuo; Kitayama, Chiho; Seto, Takafumi; Otani, Yoshio

2014-08-01

Control of transport and deposition of charged aerosol particles is important in various manufacturing processes. Aerosol visualization is an effective method to directly observe light scattering signal from laser-irradiated single aerosol particle trapped in a visualization cell. New single particle trap system triggered by light scattering pulse signal was developed in this study. The performance of the device was evaluated experimentally. Experimental setup consisted of an aerosol generator, a differential mobility analyzer (DMA), an optical particle counter (OPC) and the single particle trap system. Polystylene latex standard (PSL) particles (0.5, 1.0 and 2.0 μm) were generated and classified according to the charge by the DMA. Singly charged 0.5 and 1.0 μm particles and doubly charged 2.0 μm particles were used as test particles. The single particle trap system was composed of a light scattering signal detector and a visualization cell. When the particle passed through the detector, trigger signal with a given delay time sent to the solenoid valves upstream and downstream of the visualization cell for trapping the particle in the visualization cell. The motion of particle in the visualization cell was monitored by CCD camera and the gravitational settling velocity and the electrostatic migration velocity were measured from the video image. The aerodynamic diameter obtained from the settling velocity was in good agreement with Stokes diameter calculated from the electrostatic migration velocity for individual particles. It was also found that the aerodynamic diameter obtained from the settling velocity was a one-to-one function of the scattered light intensity of individual particles. The applicability of this system will be discussed.

Selective ion accumulation in an ICP/ITMS using a filtered noise field

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eiden, G.C.; Barinaga, C.J.; Koppenaal, D.W.

1995-12-31

Selective accumulation of ions in an ion trap mass spectrometer (ITMS) has been characterized using both single frequency and broadband resonant excitation. The goal of this work is to enhance selective accumulation of ions from plasmas and other external ion sources. The charge capacity of the ITMS is 10{sup 6} to 10{sup 7} ions, although the mass spectrum is distorted at much lower space charge. Detection of trace ions necessitates selective detection schemes such as selective trapping or optical detection. The authors report results of selective trapping studies for Sr, Y, and Zr solutions (100 ppb Y and 1 ppbmore » each Sr, Zr). {open_quotes}Background{close_quotes} ions in mass channels adjacent to the channel of interest is a worst case situation with respect to selective ejection and abundance sensitivity. Real samples will often have matrix ion m/z values much further removed from the m/z of the ions of interest. Thus, the authors also give results for a multielement solution. Ions from an inductively coupled plasma ion source are endcap injected into the ITMS. Broadband waveforms were generated by an HST-1000 (Teledyne MEC) instrument, using the filtered noise field (FNF) method. The experiment is controlled by the ITMS electronics and ICMS software. The sequence of experimental events is: ion injection at q{sub z} = 0.4 (typical), collisionally cool ions, set trapping potential for resonant excitation (q{sub z} = 0.2 to 0.6), analysis rf ramp.« less

Rayleigh-Taylor instability of two-specie laser-accelerated foils

NASA Astrophysics Data System (ADS)

Ratliff, T. H.; Yi, S. A.; Khudik, V.; Yu, T. P.; Pukhov, A.; Chen, M.; Shvets, G.

2010-11-01

When an ultra intense circularly polarized laser pulse irradiates an ultra thin film, a monoenergetic ion beam is produced with characteristics well suited for applications in science and medicine. Upon laser incidence, the electrons in the foil are pushed via the ponderomotive force to the foil rear; the charge separation field then accelerates ions. In the accelerating frame the ions are trapped in a potential well formed by the electrostatic and inertial forces. However, their energy spectrum can be quickly degraded by the Rayleigh-Taylor (RT) instability. Stabilization in the case of a two-specie foil is the subject of this poster. First, we use a 1D particle-in-cell (PIC) simulation to establish an equilibrium state of the two-specie foil in the accelerating frame. Next we perturb this equilibrium and analytically investigate the 2D RT instability. Analytical results are compared with 2-D simulations. We also investigate parametrically various effects on the RT growth rate. The protons completely separate from the carbons, and although the vacuum-carbon interface remains unstable, the large spatial extent of the carbon layer prevents perturbations from feeding through to the proton layer. The monoenergetic proton beam is shown to persist beyond the conclusion of the laser pulse interaction. [1] T.P. Yu, A. Pukhov, G. Shvets, and M Chen, Phys. Rev. Lett. (in press)

Combining Jaynes-Cummings and anti-Jaynes-Cummings dynamics in a trapped-ion system driven by a laser

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rodriguez-Lara, B.M.; Moya-Cessa, H.; Klimov, A.B.

2005-02-01

We show that, if one combines the Jaynes-Cummings and anti-Jaynes-Cummings dynamics in a trapped-ion system driven by a laser, additional series of collapses and revivals of the vibrational state of the ion can be generated.

An Orbital Trap Mass Analyzer Using a Hybrid Magnetic-Electric Field: A Simulation Study

NASA Astrophysics Data System (ADS)

Xu, Chongsheng; Wu, Fangling; Ding, Li; Ding, Chuan-Fan

2018-03-01

An orbital ion trap mass analyzer employing hybrid magnetic-electric field was designed and simulated. The trap has a rotational symmetrical structure and the hybrid trapping field was created in a toroidal space between 12 pairs of sector detection electrodes. Ion injection and ion orbital motion inside the trap were simulated using SIMION 8.1 with a user Lua program, and the required electric and magnetic field were investigated. The image charge signal can be picked up by the 12 pairs of detection electrodes and the mass resolution was evaluated using FFT. The simulated resolving power for the optimized configuration over 79,000 FWHM was obtained at the magnetic induction intensity of 0.5 Tesla in the simulation. [Figure not available: see fulltext.

Review of the High Performance Antiproton Trap (HiPAT) Experiment at the Marshall Space Flight Center

NASA Technical Reports Server (NTRS)

Pearson, J. B.; Sims, Herb; Martin, James; Chakrabarti, Suman; Lewis, Raymond; Fant, Wallace

2003-01-01

The significant energy density of matter-antimatter annihilation is attractive to the designers of future space propulsion systems, with the potential to offer a highly compact source of power. Many propulsion concepts exist that could take advantage of matter-antimatter reactions, and current antiproton production rates are sufficient to support basic proof-of-principle evaluation of technology associated with antimatter- derived propulsion. One enabling technology for such experiments is portable storage of low energy antiprotons, allowing antiprotons to be trapped, stored, and transported for use at an experimental facility. To address this need, the Marshall Space Flight Center's Propulsion Research Center is developing a storage system referred to as the High Performance Antiproton Trap (HiPAT) with a design goal of containing 10(exp 12) particles for up to 18 days. The HiPAT makes use of an electromagnetic system (Penning- Malmberg design) consisting of a 4 Telsa superconductor, high voltage electrode structure, radio frequency (RF) network, and ultra high vacuum system. To evaluate the system normal matter sources (both electron guns and ion sources) are used to generate charged particles. The electron beams ionize gas within the trapping region producing ions in situ, whereas the ion sources produce the particles external to the trapping region and required dynamic capture. A wide range of experiments has been performed examining factors such as ion storage lifetimes, effect of RF energy on storage lifetime, and ability to routinely perform dynamic ion capture. Current efforts have been focused on improving the FW rotating wall system to permit longer storage times and non-destructive diagnostics of stored ions. Typical particle detection is performed by extracting trapped ions from HiPAT and destructively colliding them with a micro-channel plate detector (providing number and energy information). This improved RF system has been used to detect various plasma modes for both electron and ion plasmas in the two traps at MSFC, including axial, cyclotron, and diocotron modes. New diagnostics are also being added to HiPAT to measure the axial density distribution of the trapped cloud to match measured RF plasma modes to plasma conditions.

The fate of b-ions in the two worlds of collision-induced dissociation.

PubMed

Waldera-Lupa, Daniel M; Stefanski, Anja; Meyer, Helmut E; Stühler, Kai

2013-12-01

Fragment analysis of proteins and peptides by mass spectrometry using collision-induced dissociation (CID) revealed that the pairwise generated N-terminal b- and C-terminal y-ions have different stabilities resulting in underrepresentation of b-ions. Detailed analyses of large-scale spectra databases and synthetic peptides underlined these observations and additionally showed that the fragmentation pattern depends on utilized CID regime. To investigate this underrepresentation further we systematically compared resonant excitation energy and beam-type CID facilitated on different mass spectrometer platforms: (i) quadrupole time-of-flight, (ii) linear ion trap and (iii) three-dimensional ion trap. Detailed analysis of MS/MS data from a standard tryptic protein digest revealed that b-ions are significantly underrepresented on all investigated mass spectrometers. By N-terminal acetylation of tryptic peptides we show for the first time that b-ion cyclization reaction significantly contributes to b-ion underrepresentation even on ion trap instruments and accounts for at most 16% of b-ion loss. © 2013.

Rotational dynamics of a diatomic molecular ion in a Paul trap

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hashemloo, A.; Dion, C. M., E-mail: claude.dion@umu.se

We present models for a heteronuclear diatomic molecular ion in a linear Paul trap in a rigid-rotor approximation, one purely classical and the other where the center-of-mass motion is treated classically, while rotational motion is quantized. We study the rotational dynamics and their influence on the motion of the center-of-mass, in the presence of the coupling between the permanent dipole moment of the ion and the trapping electric field. We show that the presence of the permanent dipole moment affects the trajectory of the ion and that it departs from the Mathieu equation solution found for atomic ions. For themore » case of quantum rotations, we also evidence the effect of the above-mentioned coupling on the rotational states of the ion.« less

High resolution mass spectrometry method and system for analysis of whole proteins and other large molecules

DOEpatents

Reilly, Peter T. A. [Knoxville, TN; Harris, William A [Naperville, IL

2010-03-02

A matrix assisted laser desorption/ionization (MALDI) method and related system for analyzing high molecular weight analytes includes the steps of providing at least one matrix-containing particle inside an ion trap, wherein at least one high molecular weight analyte molecule is provided within the matrix-containing particle, and MALDI on the high molecular weight particle while within the ion trap. A laser power used for ionization is sufficient to completely vaporize the particle and form at least one high molecular weight analyte ion, but is low enough to avoid fragmenting the high molecular weight analyte ion. The high molecular weight analyte ion is extracted out from the ion trap, and is then analyzed using a detector. The detector is preferably a pyrolyzing and ionizing detector.

Integrated Cavity QED in a linear Ion Trap Chip for Enhanced Light Collection

NASA Astrophysics Data System (ADS)

Benito, Francisco; Jonathan, Sterk; Boyan, Tabakov; Haltli, Raymond; Tigges, Chris; Stick, Daniel; Balin, Matthew; Moehring, David

2012-06-01

Realizing a scalable trapped-ion quantum information processor may require integration of tools to manipulate qubits into trapping devices. We present efforts towards integrating a 1 mm optical cavity into a microfabricated surface ion trap to efficiently connect nodes in a quantum network. The cavity is formed by a concave mirror and a flat coated silicon mirror around a linear trap where ytterbium ions can be shuttled in and out of the cavity mode. By utilizing the Purcell effect to increase the rate of spontaneous emission into the cavity mode, we expect to collect up to 13% of the emitted photons. This work was supported by Sandia's Laboratory Directed Research and Development (LDRD) and the Intelligence Advanced Research Projects Activity (IARPA). Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the US Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Improved Miniaturized Linear Ion Trap Mass Spectrometer Using Lithographically Patterned Plates and Tapered Ejection Slit

NASA Astrophysics Data System (ADS)

Tian, Yuan; Decker, Trevor K.; McClellan, Joshua S.; Bennett, Linsey; Li, Ailin; De la Cruz, Abraham; Andrews, Derek; Lammert, Stephen A.; Hawkins, Aaron R.; Austin, Daniel E.

2018-02-01

We present a new two-plate linear ion trap mass spectrometer that overcomes both performance-based and miniaturization-related issues with prior designs. Borosilicate glass substrates are patterned with aluminum electrodes on one side and wire-bonded to printed circuit boards. Ions are trapped in the space between two such plates. Tapered ejection slits in each glass plate eliminate issues with charge build-up within the ejection slit and with blocking of ions that are ejected at off-nominal angles. The tapered slit allows miniaturization of the trap features (electrode size, slit width) needed for further reduction of trap size while allowing the use of substrates that are still thick enough to provide ruggedness during handling, assembly, and in-field applications. Plate spacing was optimized during operation using a motorized translation stage. A scan rate of 2300 Th/s with a sample mixture of toluene and deuterated toluene (D8) and xylenes (a mixture of o-, m-, p-) showed narrowest peak widths of 0.33 Th (FWHM).

Interesting features of nonlinear shock equations in dissipative pair-ion-electron plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Masood, W.; National Centre for Physics; Rizvi, H.

2011-09-15

Two dimensional nonlinear electrostatic waves are studied in unmagnetized, dissipative pair-ion-electron plasmas in the presence of weak transverse perturbation. The dissipation in the system is taken into account by incorporating the kinematic viscosity of both positive and negative ions. In the linear case, a biquadratic dispersion relation is obtained, which yields the fast and slow modes in a pair-ion-electron plasma. It is shown that the limiting cases of electron-ion and pair-ion can be retrieved from the general biquadratic dispersion relation, and the differences in the characters of the waves propagating in both the cases are also highlighted. Using the smallmore » amplitude approximation method, the nonlinear Kadomtsev Petviashvili Burgers as well as Burgers-Kadomtsev Petviashvili equations are derived and their applicability for pair-ion-electron plasma is explained in detail. The present study may have relevance to understand the formation of two dimensional electrostatic shocks in laboratory produced pair-ion-electron plasmas.« less

Current technology in ion and electrothermal propulsion

NASA Technical Reports Server (NTRS)

Finke, R. C.; Murch, C. K.

1973-01-01

High performance propulsion devices, such as electrostatic ion engines and electrothermal thrusters, are achieving wide user acceptance. The current technology and projected development trends in the areas of ion and electrothermal propulsion systems and components are surveyed.

Teaching Ion-Ion, Ion-Dipole, and Dipole-Dipole Interactions

ERIC Educational Resources Information Center

Yoder, Claude H.

1977-01-01

Discusses how electrostatic interactions can be taught quantitatively through Coulomb's Law at a variety of points in a chemistry curriculum. Each type of interaction is shown at both the intramolecular and the inter-"molecular" levels. (MR)

High-voltage terminal test of a test stand for a 1-MV electrostatic accelerator

NASA Astrophysics Data System (ADS)

Park, Sae-Hoon; Kim, Yu-Seok

2015-10-01

The Korea Multipurpose Accelerator Complex has been developing a 300-kV test stand for a 1-MV electrostatic accelerator ion source. The ion source and accelerating tube will be installed in a high-pressure vessel. The ion source in the high-pressure vessel is required to have a high reliability. The test stand has been proposed and developed to confirm the stable operating conditions of the ion source. The ion source will be tested at the test stand to verify the long-time operating conditions. The test stand comprises a 300-kV high-voltage terminal, a battery for the ion-source power, a 60-Hz inverter, 200-MHz radio-frequency power supply, a 5-kV extraction power supply, a 300-kV accelerating tube, and a vacuum system. The results of the 300-kV high-voltage terminal tests are presented in this paper.

Designing of a Quadrupole Paul Ion Trap

NASA Astrophysics Data System (ADS)

Kiyani, Abouzar; Abdollahzadeh, M.; Sadat Kiai, S. M.; Zirak, A. R.

2011-08-01

The ion motion equation in a Paul ion trap known as Mathieu differential equation has been solved for the first time by using Runge-Kutta methods with 4th, 6th, and 8th orders. The first stability regions in az - qz plane and the corresponding qmax values were determined and compared. Also, the first stability regions of , , , ions in the Vdc - Vac plane were drown, and the threshold voltages for the ion separation was investigated.

The binding energies of one and two water molecules to the first transition-row metal positive ions

NASA Technical Reports Server (NTRS)

Rosi, Marzio; Bauschlicher, Charles W., Jr.

1989-01-01

The bonding of water to the transition metal positive ions is electrostatic in origin. The electrostatic bonding is enhanced by a variety of mechanisms: mixing in 4p character, 4s-3d hybridization, and 4s promotion into the compact 3d orbital. The importance of these effects varies between the different metal ions due to changes in the separation of the metal ion atomic states. Furthermore, the change in the metal-water repulsion when a second water is added also changes the relative importance of the different metal asymptotes. The second water binding energy varies from being 11 kcal/mol smaller than the first for Mn(+) to 3 kcal/mol larger for V(+) and Fe(+).

Assembling a ring-shaped crystal in a microfabricated surface ion trap

DOE PAGES

Stick, Daniel Lynn; Tabakov, Boyan; Benito, Francisco; ...

2015-09-01

We report on experiments with a microfabricated surface trap designed for confining a chain of ions in a ring. Uniform ion separation over most of the ring is achieved with a rotationally symmetric design and by measuring and suppressing undesired electric fields. After reducing stray fields, the ions are confined primarily by a radio-frequency pseudopotential and their mutual Coulomb repulsion. As a result, approximately 400 40Ca + ions with an average separation of 9 μm comprise the ion crystal.

Assembling a ring-shaped crystal in a microfabricated surface ion trap

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stick, Daniel Lynn; Tabakov, Boyan; Benito, Francisco

We report on experiments with a microfabricated surface trap designed for confining a chain of ions in a ring. Uniform ion separation over most of the ring is achieved with a rotationally symmetric design and by measuring and suppressing undesired electric fields. After reducing stray fields, the ions are confined primarily by a radio-frequency pseudopotential and their mutual Coulomb repulsion. As a result, approximately 400 40Ca + ions with an average separation of 9 μm comprise the ion crystal.

Advanced Automation for Ion Trap Mass Spectrometry-New Opportunities for Real-Time Autonomous Analysis

NASA Technical Reports Server (NTRS)

Palmer, Peter T.; Wong, C. M.; Salmonson, J. D.; Yost, R. A.; Griffin, T. P.; Yates, N. A.; Lawless, James G. (Technical Monitor)

1994-01-01

The utility of MS/MS for both target compound analysis and the structure elucidation of unknowns has been described in a number of references. A broader acceptance of this technique has not yet been realized as it requires large, complex, and costly instrumentation which has not been competitive with more conventional techniques. Recent advancements in ion trap mass spectrometry promise to change this situation. Although the ion trap's small size, sensitivity, and ability to perform multiple stages of mass spectrometry have made it eminently suitable for on-line, real-time monitoring applications, advance automation techniques are required to make these capabilities more accessible to non-experts. Towards this end we have developed custom software for the design and implementation of MS/MS experiments. This software allows the user to take full advantage of the ion trap's versatility with respect to ionization techniques, scan proxies, and ion accumulation/ejection methods. Additionally, expert system software has been developed for autonomous target compound analysis. This software has been linked to ion trap control software and a commercial data system to bring all of the steps in the analysis cycle under control of the expert system. These software development efforts and their utilization for a number of trace analysis applications will be described.

Motional studies of one and two laser-cooled trapped ions for electric-field sensing applications

NASA Astrophysics Data System (ADS)

Domínguez, F.; Gutiérrez, M. J.; Arrazola, I.; Berrocal, J.; Cornejo, J. M.; Del Pozo, J. J.; Rica, R. A.; Schmidt, S.; Solano, E.; Rodríguez, D.

2018-03-01

We have studied the dynamics of one and two laser-cooled trapped ?Ca? ions by applying electric fields of different nature along the axial direction of the trap, namely, driving the motion with a harmonic dipolar field, or with white noise. These two types of driving induce distinct motional states of the axial modes: a coherent oscillation with the dipolar field, or an enhanced Brownian motion due to an additional contribution to the heating rate from the electric noise. In both scenarios, the sensitivity of an isolated ion and a laser-cooled two-ion crystal has been evaluated and compared. The analysis and understanding of this dynamics is important towards the implementation of a novel Penning trap mass-spectroscopy technique based on optical detection, aiming at improving precision and sensitivity.

Evaluation of molecular dynamics simulation methods for ionic liquid electric double layers.

PubMed

Haskins, Justin B; Lawson, John W

2016-05-14

We investigate how systematically increasing the accuracy of various molecular dynamics modeling techniques influences the structure and capacitance of ionic liquid electric double layers (EDLs). The techniques probed concern long-range electrostatic interactions, electrode charging (constant charge versus constant potential conditions), and electrolyte polarizability. Our simulations are performed on a quasi-two-dimensional, or slab-like, model capacitor, which is composed of a polarizable ionic liquid electrolyte, [EMIM][BF4], interfaced between two graphite electrodes. To ensure an accurate representation of EDL differential capacitance, we derive new fluctuation formulas that resolve the differential capacitance as a function of electrode charge or electrode potential. The magnitude of differential capacitance shows sensitivity to different long-range electrostatic summation techniques, while the shape of differential capacitance is affected by charging technique and the polarizability of the electrolyte. For long-range summation techniques, errors in magnitude can be mitigated by employing two-dimensional or corrected three dimensional electrostatic summations, which led to electric fields that conform to those of a classical electrostatic parallel plate capacitor. With respect to charging, the changes in shape are a result of ions in the Stern layer (i.e., ions at the electrode surface) having a higher electrostatic affinity to constant potential electrodes than to constant charge electrodes. For electrolyte polarizability, shape changes originate from induced dipoles that soften the interaction of Stern layer ions with the electrode. The softening is traced to ion correlations vertical to the electrode surface that induce dipoles that oppose double layer formation. In general, our analysis indicates an accuracy dependent differential capacitance profile that transitions from the characteristic camel shape with coarser representations to a more diffuse profile with finer representations.

Dynamics of charged particles in a Paul radio-frequency quadrupole trap

NASA Technical Reports Server (NTRS)

Prestage, J. D.; Williams, A.; Maleki, L.; Djomehri, M. J.; Harabetian, E.

1991-01-01

A molecular-dynamics simulation of hundreds of ions confined in a Paul trap has been performed. The simulation includes the trapped particles' micromotion and interparticle Coulomb interactions. A random walk in velocity was implemented to bring the secular motion to a given temperature which was numerically measured. When the coupling Gamma is large the ions from concentric shells which undergo a quadrupole oscillation at the RF frequency, while the ions within a shell form a 2D hexagonal lattice. Ion clouds at 5 mK show no RF heating for q(z) less than about 0.6, whereas rapid heating is seen for qz = 0.8.

Reshaping and linking of molecules in ion-pair traps

NASA Astrophysics Data System (ADS)

Cochrane, Bryce; Naumkin, Fedor Y.

2016-01-01

A series of insertion complexes of small molecules trapped between alkali-halide counter-ions are investigated ab initio. The molecular shape is altered inside the complexes and varies in corresponding anions. Stabilities and charge distributions are investigated. Strong charge-transfer in the alkali-halide component effectively through the almost neutral molecule results in very large dipole moments. The most stable species is used to construct a dimer significantly bound via dipole-dipole interaction. Another complex with two alkali-halide diatoms trapping the molecule represents a unit of corresponding longer oligomer. This completes the array of systems with the molecule effectively in ion-pair, ion-dipole, dipole-pair electric fields.

Off-resonance energy absorption in a linear Paul trap due to mass selective resonant quenching

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sivarajah, I.; Goodman, D. S.; Wells, J. E.

Linear Paul traps (LPT) are used in many experimental studies such as mass spectrometry, atom-ion collisions, and ion-molecule reactions. Mass selective resonant quenching (MSRQ) is implemented in LPT either to identify a charged particle's mass or to remove unwanted ions from a controlled experimental environment. In the latter case, MSRQ can introduce undesired heating to co-trapped ions of different mass, whose secular motion is off resonance with the quenching ac field, which we call off-resonance energy absorption (OREA). We present simulations and experimental evidence that show that the OREA increases exponentially with the number of ions loaded into the trapmore » and with the amplitude of the off-resonance external ac field.« less

Quantum information processing between different atomic ions

NASA Astrophysics Data System (ADS)

Zhang, Xiang; Zheng, Bo; Zhang, Junhua; Um, Mark; An, Shuoming; Zhao, Tianji; Duan, Luming; Kim, Kihwan

2012-06-01

There is increasing interest in utilizing and combining the advantages of different quantum systems. Here, we discuss the experimental generation of entanglement between the quantum states of different atomic ions through the Coulomb interaction at the same linear radio-frequency trap. This scheme would be extended to implement the teleportation of quantum information from one kind of atom to the other. Moreover, the hybrid system of trapped ions is expected to play an essential role in the realization of a large quantum system, where a quantum state of one species is used for quantum operation and that of the other is for the cooling and stabilization of the whole ion chain. Finally, we will report the experimental progress on building the hybrid trapped ion system.

Design and performance of an instrument for electron impact tandem mass spectrometry and action spectroscopy of mass/charge selected macromolecular ions stored in RF ion trap*

NASA Astrophysics Data System (ADS)

Ranković, Milos Lj.; Giuliani, Alexandre; Milosavljević, Aleksandar R.

2016-06-01

A new apparatus was designed, coupling an electron gun with a linear quadrupole ion trap mass spectrometer, to perform m/ z (mass over charge) selected ion activation by electron impact for tandem mass spectrometry and action spectroscopy. We present in detail electron tracing simulations of a 300 eV electron beam inside the ion trap, design of the mechanical parts, electron optics and electronic circuits used in the experiment. We also report examples of electron impact activation tandem mass spectra for Ubiquitin protein, Substance P and Melittin peptides, at incident electron energies in the range from 280 eV to 300 eV.

Electrostatic fluctuations in collisional plasmas

NASA Astrophysics Data System (ADS)

Rozmus, W.; Brantov, A.; Fortmann-Grote, C.; Bychenkov, V. Yu.; Glenzer, S.

2017-10-01

We present a theory of electrostatic fluctuations in two-component plasmas where electrons and ions are described by Maxwellian distribution functions at unequal temperatures. Based on the exact solution of the Landau kinetic equation, that includes electron-electron, electron-ion, and ion-ion collision integrals, the dynamic form factor, S (k ⃗,ω ) , is derived for weakly coupled plasmas. The collective plasma responses at ion-acoustic, Langmuir, and entropy mode resonances are described for arbitrary wave numbers and frequencies in the entire range of plasma collisionality. The collisionless limit of S (k ⃗,ω ) and the strong-collision result based on the fluctuation-dissipation theorem and classical transport at Te=Ti are recovered and discussed. Results of several Thomson scattering experiments in the broad range of plasma parameters are described and discussed by means of our theory for S (k ⃗,ω ) .

How ions affect the structure of water.

PubMed

Hribar, Barbara; Southall, Noel T; Vlachy, Vojko; Dill, Ken A

2002-10-16

We model ion solvation in water. We use the MB model of water, a simple two-dimensional statistical mechanical model in which waters are represented as Lennard-Jones disks having Gaussian hydrogen-bonding arms. We introduce a charge dipole into MB waters. We perform (NPT) Monte Carlo simulations to explore how water molecules are organized around ions and around nonpolar solutes in salt solutions. The model gives good qualitative agreement with experiments, including Jones-Dole viscosity B coefficients, Samoilov and Hirata ion hydration activation energies, ion solvation thermodynamics, and Setschenow coefficients for Hofmeister series ions, which describe the salt concentration dependence of the solubilities of hydrophobic solutes. The two main ideas captured here are (1) that charge densities govern the interactions of ions with water, and (2) that a balance of forces determines water structure: electrostatics (water's dipole interacting with ions) and hydrogen bonding (water interacting with neighboring waters). Small ions (kosmotropes) have high charge densities so they cause strong electrostatic ordering of nearby waters, breaking hydrogen bonds. In contrast, large ions (chaotropes) have low charge densities, and surrounding water molecules are largely hydrogen bonded.

Cooling of trapped ions by resonant charge exchange

NASA Astrophysics Data System (ADS)

Dutta, Sourav; Rangwala, S. A.

2018-04-01

The two most widely used ion cooling methods are laser cooling and sympathetic cooling by elastic collisions (ECs). Here, we demonstrate another method of cooling ions that is based on resonant charge exchange (RCE) between the trapped ion and the ultracold parent atom. Specifically, trapped C s+ ions are cooled by collisions with cotrapped, ultracold Cs atoms and, separately, by collisions with cotrapped, ultracold Rb atoms. We observe that the cooling of C s+ ions by Cs atoms is more efficient than the cooling of C s+ ions by Rb atoms. This signals the presence of a cooling mechanism apart from the elastic ion-atom collision channel for the Cs-C s+ case, which is cooling by RCE. The efficiency of cooling by RCE is experimentally determined and the per-collision cooling is found to be two orders of magnitude higher than cooling by EC. The result provides the experimental basis for future studies on charge transport by electron hopping in atom-ion hybrid systems.

A single axis electrostatic beam deflection system for a 5-cm diameter ion thruster

NASA Technical Reports Server (NTRS)

Lathem, W. C.

1972-01-01

A single-axis electrostatic beam deflection system has been tested on a 5-cm diameter mercury ion thruster at a thrust level of about 0.43 mlb (25 mA beam current at 1400 volts). The accelerator voltage was 500 volts. Beam deflection capability of plus or minus 10 deg was demonstrated. A life test of 1367 hours was run at the above conditions. Results of the test indicated that the system could possibly perform for upwards of 10,000 hours.

Iodine Plasma Species Measurements in a Hall Effect Thruster Plume

DTIC Science & Technology

2013-05-01

with an ExB probe , an electrostatic analyzer (ESA), and a combined ESA/ExB probe . The distribution of xenon ions was also measured. Multiply charge...of iodine ions was measured with an ExB probe , an electrostatic analyzer (ESA), and a combined ESA/ExB probe . • Results: – Multiply charged species...Test Hardware – Vacuum test facility (6’ diameter) – Faraday probe (MIT) – ESA, ExB, ESA/ExB Probes (Plasma Controls) – Rotary probe arm (about

Single ion as a shot-noise-limited magnetic-field-gradient probe

DOE Office of Scientific and Technical Information (OSTI.GOV)

Walther, A.; Poschinger, U.; Ziesel, F.

2011-06-15

It is expected that ion-trap quantum computing can be made scalable through protocols that make use of transport of ion qubits between subregions within the ion trap. In this scenario, any magnetic field inhomogeneity the ion experiences during the transport may lead to dephasing and loss of fidelity. Here we demonstrate how to measure, and compensate for, magnetic field gradients inside a segmented ion trap, by transporting a single ion over variable distances. We attain a relative magnetic field sensitivity of {Delta}B/B{sub 0{approx}}5x10{sup -7} over a test distance of 140 {mu}m, which can be extended to the mm range, stillmore » with sub-{mu}m resolution. A fast experimental sequence is presented, facilitating its use as a magnetic-field-gradient calibration routine, and it is demonstrated that the main limitation is the quantum shot noise.« less

Efficient rotational cooling of Coulomb-crystallized molecular ions by a helium buffer gas.

PubMed

Hansen, A K; Versolato, O O; Kłosowski, L; Kristensen, S B; Gingell, A; Schwarz, M; Windberger, A; Ullrich, J; López-Urrutia, J R Crespo; Drewsen, M

2014-04-03

The preparation of cold molecules is of great importance in many contexts, such as fundamental physics investigations, high-resolution spectroscopy of complex molecules, cold chemistry and astrochemistry. One versatile and widely applied method to cool molecules is helium buffer-gas cooling in either a supersonic beam expansion or a cryogenic trap environment. Another more recent method applicable to trapped molecular ions relies on sympathetic translational cooling, through collisional interactions with co-trapped, laser-cooled atomic ions, into spatially ordered structures called Coulomb crystals, combined with laser-controlled internal-state preparation. Here we present experimental results on helium buffer-gas cooling of the rotational degrees of freedom of MgH(+) molecular ions, which have been trapped and sympathetically cooled in a cryogenic linear radio-frequency quadrupole trap. With helium collision rates of only about ten per second--that is, four to five orders of magnitude lower than in typical buffer-gas cooling settings--we have cooled a single molecular ion to a rotational temperature of 7.5(+0.9)(-0.7) kelvin, the lowest such temperature so far measured. In addition, by varying the shape of, or the number of atomic and molecular ions in, larger Coulomb crystals, or both, we have tuned the effective rotational temperature from about 7 kelvin to about 60 kelvin by changing the translational micromotion energy of the ions. The extremely low helium collision rate may allow for sympathetic sideband cooling of single molecular ions, and eventually make quantum-logic spectroscopy of buffer-gas-cooled molecular ions feasible. Furthermore, application of the present cooling scheme to complex molecular ions should enable single- or few-state manipulations of individual molecules of biological interest.

Quantum simulations of the Ising model with trapped ions: Devil's staircase and arbitrary lattice proposal

NASA Astrophysics Data System (ADS)

Korenblit, Simcha

A collection of trapped atomic ions represents one of the most attractive platforms for the quantum simulation of interacting spin networks and quantum magnetism. Spin-dependent optical dipole forces applied to an ion crystal create long-range effective spin-spin interactions and allow the simulation of spin Hamiltonians that possess nontrivial phases and dynamics. We trap linear chains of 171Yb+ ions in a Paul trap, and constrain the occupation of energy levels to the ground hyperne clock-states, creating a qubit or pseudo-spin 1/2 system. We proceed to implement spin-spin couplings between two ions using the far detuned Molmer-Sorenson scheme and perform adiabatic quantum simulations of Ising Hamiltonians with long-range couplings. We then demonstrate our ability to control the sign and relative strength of the interaction between three ions. Using this control, we simulate a frustrated triangular lattice, and for the first time establish an experimental connection between frustration and quantum entanglement. We then scale up our simulation to show phase transitions from paramagnetism to ferromagnetism for nine ions, and to anti-ferromagnetism for sixteen ions. The experimental work culminates with our most complicated Hamiltonian---a long range anti-ferromagnetic Ising interaction between 10 ions with a biasing axial field. Theoretical work presented in this thesis shows how the approach to quantum simulation utilized in this thesis can be further extended and improved. It is shown how appropriate design of laser fields can provide for arbitrary multidimensional spin-spin interaction graphs even for the case of a linear spatial array of ions. This scheme uses currently existing trap technology and is scalable to levels where classical methods of simulation are intractable.

Effect of 30 MeV Li3+ ion and 8 MeV electron irradiation on N-channel MOSFETs

NASA Astrophysics Data System (ADS)

Prakash, A. P. G.; Ganesh, K. C. P.; Nagesha, Y. N.; Umakanth, D.; Arora, S. K.; Siddappa, K.

The effect of 30 MeV Li3+ ion and 8 MeV electron irradiation on the threshold voltage (V-TH), the voltage shift due to interface trapped charge (DeltaV(Nit)), the voltage shift due to oxide trapped charge (DeltaV(Not)), the density of interface trapped charge (DeltaN(it)), the density of oxide trapped charge (DeltaN(ot) ) and the drain saturation current (I-D Sat) were studied as a function of fluence. Considerable increase in DeltaN(it) and DeltaN(ot) , and decrease in V-TH and I-D Sat were observed in both types of irradiation. The observed difference in the properties of Li3+ ion and electron irradiated MOSFETs are interpreted on the basis of energy loss process associated with the type of radiation. The study showed that the 30 MeV Li3+ ion irradiation produce more damage when compared to the 8 MeV electron irradiation because of the higher electronic energy loss value. High temperature annealing studies showed that trapped charge generated during ion and electron irradiation was annealed out at 500 degreesC.

Single-ion, transportable optical atomic clocks

NASA Astrophysics Data System (ADS)

Delehaye, Marion; Lacroûte, Clément

2018-03-01

For the past 15 years, tremendous progress within the fields of laser stabilization, optical frequency combs and atom cooling and trapping have allowed the realization of optical atomic clocks with unrivaled performances. These instruments can perform frequency comparisons with fractional uncertainties well below ?, finding applications in fundamental physics tests, relativistic geodesy and time and frequency metrology. Even though most optical clocks are currently laboratory setups, several proposals for using these clocks for field measurements or within an optical clock network have been published, and most of time and frequency metrology institutes have started to develop transportable optical clocks. For the purpose of this special issue, we chose to focus on trapped-ion optical clocks. Even though their short-term fractional frequency stability is impaired by a lower signal-to-noise ratio, they offer a high potential for compactness: trapped ions demand low optical powers and simple loading schemes, and can be trapped in small vacuum chambers. We review recent advances on the clock key components, including ion trap and ultra-stable optical cavity, as well as existing projects and experiments which draw the picture of what future transportable, single-ion optical clocks may resemble.

Non-thermalization in trapped atomic ion spin chains

NASA Astrophysics Data System (ADS)

Hess, P. W.; Becker, P.; Kaplan, H. B.; Kyprianidis, A.; Lee, A. C.; Neyenhuis, B.; Pagano, G.; Richerme, P.; Senko, C.; Smith, J.; Tan, W. L.; Zhang, J.; Monroe, C.

2017-10-01

Linear arrays of trapped and laser-cooled atomic ions are a versatile platform for studying strongly interacting many-body quantum systems. Effective spins are encoded in long-lived electronic levels of each ion and made to interact through laser-mediated optical dipole forces. The advantages of experiments with cold trapped ions, including high spatio-temporal resolution, decoupling from the external environment and control over the system Hamiltonian, are used to measure quantum effects not always accessible in natural condensed matter samples. In this review, we highlight recent work using trapped ions to explore a variety of non-ergodic phenomena in long-range interacting spin models, effects that are heralded by the memory of out-of-equilibrium initial conditions. We observe long-lived memory in static magnetizations for quenched many-body localization and prethermalization, while memory is preserved in the periodic oscillations of a driven discrete time crystal state. This article is part of the themed issue 'Breakdown of ergodicity in quantum systems: from solids to synthetic matter'.

Non-thermalization in trapped atomic ion spin chains.

PubMed

Hess, P W; Becker, P; Kaplan, H B; Kyprianidis, A; Lee, A C; Neyenhuis, B; Pagano, G; Richerme, P; Senko, C; Smith, J; Tan, W L; Zhang, J; Monroe, C

2017-12-13

Linear arrays of trapped and laser-cooled atomic ions are a versatile platform for studying strongly interacting many-body quantum systems. Effective spins are encoded in long-lived electronic levels of each ion and made to interact through laser-mediated optical dipole forces. The advantages of experiments with cold trapped ions, including high spatio-temporal resolution, decoupling from the external environment and control over the system Hamiltonian, are used to measure quantum effects not always accessible in natural condensed matter samples. In this review, we highlight recent work using trapped ions to explore a variety of non-ergodic phenomena in long-range interacting spin models, effects that are heralded by the memory of out-of-equilibrium initial conditions. We observe long-lived memory in static magnetizations for quenched many-body localization and prethermalization, while memory is preserved in the periodic oscillations of a driven discrete time crystal state.This article is part of the themed issue 'Breakdown of ergodicity in quantum systems: from solids to synthetic matter'. © 2017 The Author(s).

Efficient Raman sideband cooling of trapped ions to their motional ground state

NASA Astrophysics Data System (ADS)

Che, H.; Deng, K.; Xu, Z. T.; Yuan, W. H.; Zhang, J.; Lu, Z. H.

2017-07-01

Efficient cooling of trapped ions is a prerequisite for various applications of the ions in precision spectroscopy, quantum information, and coherence control. Raman sideband cooling is an effective method to cool the ions to their motional ground state. We investigate both numerically and experimentally the optimization of Raman sideband cooling strategies and propose an efficient one, which can simplify the experimental setup as well as reduce the number of cooling pulses. Several cooling schemes are tested and compared through numerical simulations. The simulation result shows that the fixed-width pulses and varied-width pulses have almost the same efficiency for both the first-order and the second-order Raman sideband cooling. The optimized strategy is verified experimentally. A single 25Mg+ ion is trapped in a linear Paul trap and Raman sideband cooled, and the achieved average vibrational quantum numbers under different cooling strategies are evaluated. A good agreement between the experimental result and the simulation result is obtained.

Internal Energy Distribution in Sympathetically Cooled Molecular Ions

NASA Astrophysics Data System (ADS)

Thompson, Robert I.; Fisher, Amy; Harmon, Thomas; Winslade, Clayton; Ahmadi, Nasser

2002-05-01

Over the past year a research program at the University of Calgary has begun looking at the distribution of energy in the internal degrees of freedom (vibrational and rotational) of trapped and sympathetically cooled molecular ions. Ion traps are capable of holding mixed samples of charged atoms and molecules simultaneously. Atomic ions in the trapped cloud can be laser cooled by traditional techniques. The molecular ions are not directly laser cooled, but all of the trapped particles are charged so they interact strongly through Coulomb forces. It has been experimentally demonstrated that the external or translational degrees of freedom of the non-laser-cooled species are significantly lowered through this interaction (e.g. [1]). However, there is little known about the energy distribution in the in the internal degrees of freedom. This poster will outline the results of our theoretical work, as well as the technical design, construction, and initial work in the laboratory. [1] T. Baba and I. Waki, Jpn. J. Appl. Phys. 35, L1134 (1996).

Correlation between y-type ions observed in ion trap and triple quadrupole mass spectrometers.

PubMed

Sherwood, Carly A; Eastham, Ashley; Lee, Lik Wee; Risler, Jenni; Vitek, Olga; Martin, Daniel B

2009-09-01

Multiple reaction monitoring mass spectrometry (MRM-MS) is a technique for high-sensitivity targeted analysis. In proteomics, MRM-MS can be used to monitor and quantify a peptide based on the production of expected fragment peaks from the selected peptide precursor ion. The choice of which fragment ions to monitor in order to achieve maximum sensitivity in MRM-MS can potentially be guided by existing MS/MS spectra. However, because the majority of discovery experiments are performed on ion trap platforms, there is concern in the field regarding the generalizability of these spectra to MRM-MS on a triple quadrupole instrument. In light of this concern, many operators perform an optimization step to determine the most intense fragments for a target peptide on a triple quadrupole mass spectrometer. We have addressed this issue by targeting, on a triple quadrupole, the top six y-ion peaks from ion trap-derived consensus library spectra for 258 doubly charged peptides from three different sample sets and quantifying the observed elution curves. This analysis revealed a strong correlation between the y-ion peak rank order and relative intensity across platforms. This suggests that y-type ions obtained from ion trap-based library spectra are well-suited for generating MRM-MS assays for triple quadrupoles and that optimization is not required for each target peptide.

All-diode-laser cooling of Sr+ isotope ions for analytical applications

NASA Astrophysics Data System (ADS)

Jung, Kyunghun; Yamamoto, Kazuhiro; Yamamoto, Yuta; Miyabe, Masabumi; Wakaida, Ikuo; Hasegawa, Shuichi

2017-06-01

Trapping and cooling of Sr+ isotope ions by an all-diode-laser system has been demonstrated in order to develop a novel mass spectrometric technique in combination with ion trap-laser cooling. First, we constructed external cavity diode lasers and associated stabilization apparatus for laser cooling of Sr+ ions. The transition frequencies confirmed by optogalvanic spectroscopy enabled successful cooling of 88Sr+ ions. An image of two trapped ions has been captured by CCD camera. Minor isotopes, 84Sr+ and 86Sr+, were also cooled and trapped. From an analysis of the observed spectra of a string crystal of each isotope, the isotope shifts of the cooling transition (5s 2S1/2 → 5p 2P1/2) of Sr+ ions were determined to be +371(8) MHz for Δν84-88 and +169(8) MHz for Δν86-88. In the case of the repumping transition (4d 2D3/2 → 5p 2P1/2), Δν84-88 and Δν86-88 were measured to be -833(6) and -400(5) MHz, respectively. These values are in good agreement with previously reported values.

The effect of atomic response time in the theory of Doppler cooling of trapped ions

NASA Astrophysics Data System (ADS)

Janacek, H.; Steane, A. M.; Lucas, D. M.; Stacey, D. N.

2018-03-01

We describe a simple approach to the problem of incorporating the response time of an atom or ion being Doppler-cooled into the theory of the cooling process. The system being cooled does not in general respond instantly to the changing laser frequencies it experiences in its rest frame, and this 'dynamic effect' can affect significantly the temperatures attainable. It is particularly important for trapped ions when there is a slow decay out of the cooling cycle requiring the use of a repumping beam. We treat the cases of trapped ions with two and three internal states, then apply the theory to ?. For this ion experimental data exist showing the ion to be cold under conditions for which heating is predicted if the dynamic effect is neglected. The present theory accounts for the observed behaviour.

Experimental apparatus for overlapping a ground-state cooled ion with ultracold atoms

NASA Astrophysics Data System (ADS)

Meir, Ziv; Sikorsky, Tomas; Ben-shlomi, Ruti; Akerman, Nitzan; Pinkas, Meirav; Dallal, Yehonatan; Ozeri, Roee

2018-03-01

Experimental realizations of charged ions and neutral atoms in overlapping traps are gaining increasing interest due to their wide research application ranging from chemistry at the quantum level to quantum simulations of solid state systems. In this paper, we describe our experimental system in which we overlap a single ground-state cooled ion trapped in a linear Paul trap with a cloud of ultracold atoms such that both constituents are in the ?K regime. Excess micromotion (EMM) currently limits atom-ion interaction energy to the mK energy scale and above. We demonstrate spectroscopy methods and compensation techniques which characterize and reduce the ion's parasitic EMM energy to the ?K regime even for ion crystals of several ions. We further give a substantial review on the non-equilibrium dynamics which governs atom-ion systems. The non-equilibrium dynamics is manifested by a power law distribution of the ion's energy. We also give an overview on the coherent and non-coherent thermometry tools which can be used to characterize the ion's energy distribution after single to many atom-ion collisions.

Experiments Towards Mitigation of Motional Heating in Trapped Ion Quantum Information Processing

DTIC Science & Technology

2016-02-27

in our surface electrode trap chips. The distance-dependence measurement was taken by Deslauri- ers et al . using a 3D needle trap [9]. These results...heating rate fit for this data is shown in Figure 6-5. 68 Delay time (ms) A ve ra ge M o ti o n al O cc u p at io n al L ev el ( ) <n...Wineland. Cooling in traps. Physica Scripta, 22:216–223, 1988 . [18] W. Itano and D. Wineland. Laser cooling of ions stored in harmonic and penning traps

Asymmetric ion trap

DOEpatents

Barlow, S.E.; Alexander, M.L.; Follansbee, J.C.

1997-12-02

An ion trap having two end cap electrodes disposed asymmetrically about a center of a ring electrode is disclosed. The inner surface of the end cap electrodes are conformed to an asymmetric pair of equipotential lines of the harmonic formed by the application of voltages to the electrodes. The asymmetry of the end cap electrodes allows ejection of charged species through the closer of the two electrodes which in turn allows for simultaneously detecting anions and cations expelled from the ion trap through the use of two detectors charged with opposite polarity. 4 figs.

Next Generation JPL Ultra-Stable Trapped Ion Atomic Clocks

NASA Technical Reports Server (NTRS)

Burt, Eric; Tucker, Blake; Larsen, Kameron; Hamell, Robert; Tjoelker, Robert

2013-01-01

Over the past decade, trapped ion atomic clock development at the Jet Propulsion Laboratory (JPL) has focused on two directions: 1) new atomic clock technology for space flight applications that require strict adherence to size, weight, and power requirements, and 2) ultra-stable atomic clocks, usually for terrestrial applications emphasizing ultimate performance. In this paper we present a new ultra-stable trapped ion clock designed, built, and tested in the second category. The first new standard, L10, will be delivered to the Naval Research Laboratory for use in characterizing DoD space clocks.

Electrostatic waves driven by electron beam in lunar wake plasma

NASA Astrophysics Data System (ADS)

Sreeraj, T.; Singh, S. V.; Lakhina, G. S.

2018-05-01

A linear analysis of electrostatic waves propagating parallel to the ambient field in a four component homogeneous, collisionless, magnetised plasma comprising fluid protons, fluid He++, electron beam, and suprathermal electrons following kappa distribution is presented. In the absence of electron beam streaming, numerical analysis of the dispersion relation shows six modes: two electron acoustic modes (modes 1 and 6), two fast ion acoustic modes (modes 2 and 5), and two slow ion acoustic modes (modes 3 and 4). The modes 1, 2 and 3 and modes 4, 5, and 6 have positive and negative phase speeds, respectively. With an increase in electron beam speed, the mode 6 gets affected the most and the phase speed turns positive from negative. The mode 6 thus starts to merge with modes 2 and 3 and generates the electron beam driven fast and slow ion acoustic waves unstable with a finite growth. The electron beam driven slow ion-acoustic waves occur at lower wavenumbers, whereas fast ion-acoustic waves occur at a large value of wavenumbers. The effect of various other parameters has also been studied. We have applied this analysis to the electrostatic waves observed in lunar wake during the first flyby of the ARTEMIS mission. The analysis shows that the low (high) frequency waves observed in the lunar wake could be the electron beam driven slow (fast) ion-acoustic modes.

The Effects of Hydrogen Band EMIC Waves on Ring Current H+ Ions

NASA Astrophysics Data System (ADS)

Wang, Zhiqiang; Zhai, Hao; Gao, Zhuxiu

2017-12-01

Hydrogen band electromagnetic ion cyclotron (EMIC) waves have received much attention recently because they are found to frequently span larger spatial areas than the other band EMIC waves. Using test particle simulations, we study the nonlinear effects of hydrogen band EMIC waves on ring current H+ ions. A dimensionless parameter R is used to characterize the competition between wave-induced and adiabatic motions. The results indicate that there are three regimes of wave-particle interactions for typical 35 keV H+ ions at L = 5: diffusive (quasi-linear) behavior when αeq ≤ 35° (R ≥ 2.45), the nonlinear phase trapping when 35° < αeq < 50° (0.75 < R < 2.45), and both the nonlinear phase bunching and phase trapping when αeq ≥ 50° (R ≤ 0.75). The phase trapping can transport H+ ions toward large pitch angle, while the phase bunching has the opposite effect. The phase-trapped H+ ions can be significantly accelerated (from 35 keV to over 500 keV) in about 4 min and thus contribute to the formation of high energy components of ring current ions. The results suggest that the effect of hydrogen band EMIC waves is not ignorable in the nonlinear acceleration and resonance scattering of ring current H+ ions.

Restoring the consistency with the contact density theorem of a classical density functional theory of ions at a planar electrical double layer.

PubMed

Gillespie, Dirk

2014-11-01

Classical density functional theory (DFT) of fluids is a fast and efficient theory to compute the structure of the electrical double layer in the primitive model of ions where ions are modeled as charged, hard spheres in a background dielectric. While the hard-core repulsive component of this ion-ion interaction can be accurately computed using well-established DFTs, the electrostatic component is less accurate. Moreover, many electrostatic functionals fail to satisfy a basic theorem, the contact density theorem, that relates the bulk pressure, surface charge, and ion densities at their distances of closest approach for ions in equilibrium at a smooth, hard, planar wall. One popular electrostatic functional that fails to satisfy the contact density theorem is a perturbation approach developed by Kierlik and Rosinberg [Phys. Rev. A 44, 5025 (1991)PLRAAN1050-294710.1103/PhysRevA.44.5025] and Rosenfeld [J. Chem. Phys. 98, 8126 (1993)JCPSA60021-960610.1063/1.464569], where the full free-energy functional is Taylor-expanded around a bulk (homogeneous) reference fluid. Here, it is shown that this functional fails to satisfy the contact density theorem because it also fails to satisfy the known low-density limit. When the functional is corrected to satisfy this limit, a corrected bulk pressure is derived and it is shown that with this pressure both the contact density theorem and the Gibbs adsorption theorem are satisfied.

Adjustable Spin-Spin Interaction with 171Yb+ ions and Addressing of a Quantum Byte

NASA Astrophysics Data System (ADS)

Wunderlich, Christof

2015-05-01

Trapped atomic ions are a well-advanced physical system for investigating fundamental questions of quantum physics and for quantum information science and its applications. When contemplating the scalability of trapped ions for quantum information science one notes that the use of laser light for coherent operations gives rise to technical and also physical issues that can be remedied by replacing laser light by microwave (MW) and radio-frequency (RF) radiation employing suitably modified ion traps. Magnetic gradient induced coupling (MAGIC) makes it possible to coherently manipulate trapped ions using exclusively MW and RF radiation. After introducing the general concept of MAGIC, I shall report on recent experimental progress using 171Yb+ ions, confined in a suitable Paul trap, as effective spin-1/2 systems interacting via MAGIC. Entangling gates between non-neighbouring ions will be presented. The spin-spin coupling strength is variable and can be adjusted by variation of the secular trap frequency. In general, executing a quantum gate with a single qubit, or a subset of qubits, affects the quantum states of all other qubits. This reduced fidelity of the whole quantum register may preclude scalability. We demonstrate addressing of individual qubits within a quantum byte (eight qubits interacting via MAGIC) using MW radiation and measure the error induced in all non-addressed qubits (cross-talk) associated with the application of single-qubit gates. The measured cross-talk is on the order 10-5 and therefore below the threshold commonly agreed sufficient to efficiently realize fault-tolerant quantum computing. Furthermore, experimental results on continuous and pulsed dynamical decoupling (DD) for protecting quantum memories and quantum gates against decoherence will be briefly discussed. Finally, I report on using continuous DD to realize a broadband ultrasensitive single-atom magnetometer.

Particle trapping in 3-D using a single fiber probe with an annular light distribution.

PubMed

Taylor, R; Hnatovsky, C

2003-10-20

A single optical fiber probe has been used to trap a solid 2 ìm diameter glass bead in 3-D in water. Optical confinement in 2-D was produced by the annular light distribution emerging from a selectively chemically etched, tapered, hollow tipped metalized fiber probe. Confinement of the bead in 3-D was achieved by balancing an electrostatic force of attraction towards the tip and the optical scattering force pushing the particle away from the tip.

Confocal shift interferometry of coherent emission from trapped dipolar excitons

DOE Office of Scientific and Technical Information (OSTI.GOV)

Repp, J.; Nanosystems Initiative Munich; Center for NanoScience and Fakultät für Physik, Ludwig-Maximilians-Universität, Geschwister-Scholl-Platz 1, 80539 München

2014-12-15

We introduce a confocal shift-interferometer based on optical fibers. The presented spectroscopy allows measuring coherence maps of luminescent samples with a high spatial resolution even at cryogenic temperatures. We apply the spectroscopy onto electrostatically trapped, dipolar excitons in a semiconductor double quantum well. We find that the measured spatial coherence length of the excitonic emission coincides with the point spread function of the confocal setup. The results are consistent with a temporal coherence of the excitonic emission down to temperatures of 250 mK.

Ion-Flow-Induced Excitation of Electrostatic Cyclotron Mode in Magnetized Dusty Plasma

NASA Astrophysics Data System (ADS)

Bezbaruah, P.; Das, N.

2018-05-01

The stability of electrostatic cyclotron mode is investigated in a flowing magnetized dusty plasma in the presence of strong ion-neutral collisions. In the high magnetic field limit, when the dust magnetization becomes important, it is expected that the collective behavior of magnetized dust grains suspended in the near-sheath region substantially influences the dispersion properties of electrostatic modes. The growth/damping of the collective excitation is significantly controlled by such parameters as the ion-neutral collision frequency, Mach number, and magnetic field strength. In our case, the explicit dependence of the Mach number on the magnetic field and collision frequency has been taken into account and possible implications on the stability of the mode is analyzed. Streaming instability of cyclotron modes may be important to understand issues related to the interaction mechanism between dust grains and other associated phenomena like Coulomb crystallization, phase behavior, transport properties, etc., in the relatively strong magnetic field limit, which is currently accessible in the DPD (Kiel University) and MDPX (PSL, Auburn University) experiments.

Impact of local electrostatic field rearrangement on field ionization

NASA Astrophysics Data System (ADS)

Katnagallu, Shyam; Dagan, Michal; Parviainen, Stefan; Nematollahi, Ali; Grabowski, Blazej; Bagot, Paul A. J.; Rolland, Nicolas; Neugebauer, Jörg; Raabe, Dierk; Vurpillot, François; Moody, Michael P.; Gault, Baptiste

2018-03-01

Field ion microscopy allows for direct imaging of surfaces with true atomic resolution. The high charge density distribution on the surface generates an intense electric field that can induce ionization of gas atoms. We investigate the dynamic nature of the charge and the consequent electrostatic field redistribution following the departure of atoms initially constituting the surface in the form of an ion, a process known as field evaporation. We report on a new algorithm for image processing and tracking of individual atoms on the specimen surface enabling quantitative assessment of shifts in the imaged atomic positions. By combining experimental investigations with molecular dynamics simulations, which include the full electric charge, we confirm that change is directly associated with the rearrangement of the electrostatic field that modifies the imaging gas ionization zone. We derive important considerations for future developments of data reconstruction in 3D field ion microscopy, in particular for precise quantification of lattice strains and characterization of crystalline defects at the atomic scale.

Imaging thermal plasma mass and velocity analyzer

NASA Astrophysics Data System (ADS)

Yau, Andrew W.; Howarth, Andrew

2016-07-01

We present the design and principle of operation of the imaging ion mass and velocity analyzer on the Enhanced Polar Outflow Probe (e-POP), which measures low-energy (1-90 eV/e) ion mass composition (1-40 AMU/e) and velocity distributions using a hemispherical electrostatic analyzer (HEA), a time-of-flight (TOF) gate, and a pair of toroidal electrostatic deflectors (TED). The HEA and TOF gate measure the energy-per-charge and azimuth of each detected ion and the ion transit time inside the analyzer, respectively, providing the 2-D velocity distribution of each major ionospheric ion species and resolving the minor ion species under favorable conditions. The TED are in front of the TOF gate and optionally sample ions at different elevation angles up to ±60°, for measurement of 3-D velocity distribution. We present examples of observation data to illustrate the measurement capability of the analyzer, and show the occurrence of enhanced densities of heavy "minor" O++, N+, and molecular ions and intermittent, high-velocity (a few km/s) upward and downward flowing H+ ions in localized regions of the quiet time topside high-latitude ionosphere.