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Sprenkle RT, Bergeson SD, Silvestri LG, Murillo MS. Ultracold neutral plasma expansion in a strong uniform magnetic field. Phys Rev E 2022; 105:045201. [PMID: 35590663 DOI: 10.1103/physreve.105.045201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Accepted: 02/16/2022] [Indexed: 06/15/2023]
Abstract
In strongly magnetized neutral plasmas, electron motion is reduced perpendicular to the magnetic field direction. This changes dynamical plasma properties such as temperature equilibration, spatial density evolution, electron pressure, and thermal and electrical conductivity. In this paper we report measurements of free plasma expansion in the presence of a strong magnetic field. We image laser-induced fluorescence from an ultracold neutral Ca^{+} plasma to map the plasma size as a function of time for a range of magnetic field strengths. The asymptotic expansion velocity perpendicular to the magnetic field direction falls rapidly with increasing magnetic field strength. We observe that the initially Gaussian spatial distribution remains Gaussian throughout the expansion in both the parallel and perpendicular directions. We compare these observations with a diffusion model and with a self-similar expansion model and show that neither of these models reproduces the observed behavior over the entire range of magnetic fields used in this study. Modeling the expansion of a magnetized ultracold plasma poses a nontrivial theoretical challenge.
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Affiliation(s)
- R Tucker Sprenkle
- Department of Physics and Astronomy, Brigham Young University, Provo, Utah 84602, USA
| | - S D Bergeson
- Department of Physics and Astronomy, Brigham Young University, Provo, Utah 84602, USA
| | - Luciano G Silvestri
- Department of Computational Mathematics, Science and Engineering, Michigan State University, East Lansing, Michigan 48824, USA
| | - Michael S Murillo
- Department of Computational Mathematics, Science and Engineering, Michigan State University, East Lansing, Michigan 48824, USA
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2
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Gorman GM, Warrens MK, Bradshaw SJ, Killian TC. Magnetic Confinement of an Ultracold Neutral Plasma. PHYSICAL REVIEW LETTERS 2021; 126:085002. [PMID: 33709740 DOI: 10.1103/physrevlett.126.085002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 01/05/2021] [Accepted: 01/22/2021] [Indexed: 06/12/2023]
Abstract
We demonstrate magnetic confinement of an ultracold neutral plasma (UCNP) created at the null of a biconic cusp, or quadrupole magnetic field. Initially, the UCNP expands due to electron thermal pressure. As the plasma encounters stronger fields, expansion slows and the density distribution molds to the field. UCNP electrons are strongly magnetized over most of the plasma, while ion magnetization is only significant at the boundaries. Observations suggest that electrons and ions are predominantly trapped by magnetic mirroring and ambipolar electric fields, respectively. Confinement times approach 0.5 ms, while unmagnetized plasmas dissipate on a timescale of a few tens of microseconds.
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Affiliation(s)
- G M Gorman
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA
| | - M K Warrens
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA
| | - S J Bradshaw
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA
| | - T C Killian
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA
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3
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Dharodi VS, Murillo MS. Sculpted ultracold neutral plasmas. Phys Rev E 2020; 101:023207. [PMID: 32168665 DOI: 10.1103/physreve.101.023207] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Accepted: 02/03/2020] [Indexed: 06/10/2023]
Abstract
Ultracold neutral plasma (UNP) experiments allow for careful control of plasma properties across Coulomb coupling regimes. Here, we examine how UNPs can be used to study heterogeneous, nonequilibrium phenomena, including nonlinear waves, transport, hydrodynamics, kinetics, stopping power, and instabilities. Through a series of molecular dynamics simulations, we have explored UNPs formed with spatially modulated ionizing radiation. We have developed a computational model for such sculpted UNPs that includes an ionic screened Coulomb interaction with a spatiotemporal screening length, and Langevin-based spatial ion-electron and ion-neutral collisions. We have also developed a hydrodynamics model and have extracted its field quantities (density, flow velocity, and temperature) from the molecular dynamics simulation data, allowing us to investigate kinetics by examining moment ratios and phase-space dynamics; we find that it is possible to create UNPs that vary from nearly perfect fluids (Euler limit) to highly kinetic plasmas. We have examined plasmas in three geometries: a solid rod, a hollow rod, and a gapped slab; we have studied basic properties of these plasmas, including the spatial Coulomb coupling parameter. By varying the initial conditions, we find that we can design experimental plasmas that would allow the exploration of a wide range of phenomena, including shock and blast waves, stopping power, two-stream instabilities, and much more. Using an evaporative cooling geometry, our results suggest that much larger Coulomb couplings can be achieved, possibly in excess of 10.
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Affiliation(s)
- Vikram S Dharodi
- Department of Computational Mathematics, Science, and Engineering, Michigan State University, East Lansing, Michigan 48824, USA
| | - Michael S Murillo
- Department of Computational Mathematics, Science, and Engineering, Michigan State University, East Lansing, Michigan 48824, USA
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Sprenkle T, Dodson A, McKnight Q, Spencer R, Bergeson S, Diaw A, Murillo MS. Ion friction at small values of the Coulomb logarithm. Phys Rev E 2019; 99:053206. [PMID: 31212549 DOI: 10.1103/physreve.99.053206] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Indexed: 11/07/2022]
Abstract
Transport properties of high-energy-density plasmas are influenced by the ion collision rate. Traditionally, this rate involves the Coulomb logarithm, lnΛ. Typical values of lnΛ are ≈10-20 in kinetic theories where transport properties are dominated by weak-scattering events caused by long-range forces. The validity of these theories breaks down for strongly coupled plasmas, when lnΛ is of order one. We present measurements and simulations of collision data in strongly coupled plasmas when lnΛ is small. Experiments are carried out in the first dual-species ultracold neutral plasma (UNP), using Ca^{+} and Yb^{+} ions. We find strong collisional coupling between the different ion species in the bulk of the plasma. We simulate the plasma using a two-species fluid code that includes Coulomb logarithms derived from either a screened Coulomb potential or a the potential of mean force. We find generally good agreement between the experimental measurements and the simulations. With some improvements, the mixed Ca^{+} and Yb^{+} dual-species UNP will be a promising platform for testing theoretical expressions for lnΛ and collision cross-sections from kinetic theories through measurements of energy relaxation, stopping power, two-stream instabilities, and the evolution of sculpted distribution functions in an idealized environment in which the initial temperatures, densities, and charge states are accurately known.
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Affiliation(s)
- Tucker Sprenkle
- Department of Physics and Astronomy, Brigham Young University, Provo, Utah 84602, USA
| | - Adam Dodson
- Department of Physics and Astronomy, Brigham Young University, Provo, Utah 84602, USA
| | - Quinton McKnight
- Department of Physics and Astronomy, Brigham Young University, Provo, Utah 84602, USA
| | - Ross Spencer
- Department of Physics and Astronomy, Brigham Young University, Provo, Utah 84602, USA
| | - Scott Bergeson
- Department of Physics and Astronomy, Brigham Young University, Provo, Utah 84602, USA
| | - Abdourahmane Diaw
- Computational Physics and Methods Group, Los Alamos National Laboratory, Los Alamos, New Mexico 87544, USA
| | - Michael S Murillo
- Department of Computational Mathematics, Science and Engineering, Michigan State University, East Lansing, Michigan 48824, USA
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5
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Langin TK, Gorman GM, Killian TC. Laser cooling of ions in a neutral plasma. Science 2019; 363:61-64. [PMID: 30606841 DOI: 10.1126/science.aat3158] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Accepted: 11/13/2018] [Indexed: 11/02/2022]
Abstract
Laser cooling of a neutral plasma is a challenging task because of the high temperatures typically associated with the plasma state. By using an ultracold neutral plasma created by photoionization of an ultracold atomic gas, we avoid this obstacle and demonstrate laser cooling of ions in a neutral plasma. After 135 microseconds of cooling, we observed a reduction in ion temperature by up to a factor of four, with the temperature reaching as low as 50(4) millikelvin. This pushes laboratory studies of neutral plasmas deeper into the strongly coupled regime, beyond the limits of validity of current kinetic theories for calculating transport properties. The same optical forces also retard the plasma expansion, opening avenues for neutral-plasma confinement and manipulation.
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Affiliation(s)
- Thomas K Langin
- Department of Physics and Astronomy, Rice University, 6100 Main Street, Houston, TX 77005, USA
| | - Grant M Gorman
- Department of Physics and Astronomy, Rice University, 6100 Main Street, Houston, TX 77005, USA
| | - Thomas C Killian
- Department of Physics and Astronomy, Rice University, 6100 Main Street, Houston, TX 77005, USA.
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Lyon M, Rolston SL. Ultracold neutral plasmas. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2017; 80:017001. [PMID: 27852983 DOI: 10.1088/0034-4885/80/1/017001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
By photoionizing samples of laser-cooled atoms with laser light tuned just above the ionization limit, plasmas can be created with electron and ion temperatures below 10 K. These ultracold neutral plasmas have extended the temperature bounds of plasma physics by two orders of magnitude. Table-top experiments, using many of the tools from atomic physics, allow for the study of plasma phenomena in this new regime with independent control over the density and temperature of the plasma through the excitation process. Characteristic of these systems is an inhomogeneous density profile, inherited from the density distribution of the laser-cooled neutral atom sample. Most work has dealt with unconfined plasmas in vacuum, which expand outward at velocities of order 100 m/s, governed by electron pressure, and with lifetimes of order 100 μs, limited by stray electric fields. Using detection of charged particles and optical detection techniques, a wide variety of properties and phenomena have been observed, including expansion dynamics, collective excitations in both the electrons and ions, and collisional properties. Through three-body recombination collisions, the plasmas rapidly form Rydberg atoms, and clouds of cold Rydberg atoms have been observed to spontaneously avalanche ionize to form plasmas. Of particular interest is the possibility of the formation of strongly coupled plasmas, where Coulomb forces dominate thermal motion and correlations become important. The strongest impediment to strong coupling is disorder-induced heating, a process in which Coulomb energy from an initially disordered sample is converted into thermal energy. This restricts electrons to a weakly coupled regime and leaves the ions barely within the strongly coupled regime. This review will give an overview of the field of ultracold neutral plasmas, from its inception in 1999 to current work, including efforts to increase strong coupling and effects on plasma properties due to strong coupling.
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Affiliation(s)
- M Lyon
- Joint Quantum Institute, University of Maryland, College Park and NIST, College Park, MD 20742, USA
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Langin TK, Strickler T, Maksimovic N, McQuillen P, Pohl T, Vrinceanu D, Killian TC. Demonstrating universal scaling for dynamics of Yukawa one-component plasmas after an interaction quench. Phys Rev E 2016; 93:023201. [PMID: 26986426 DOI: 10.1103/physreve.93.023201] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Indexed: 06/05/2023]
Abstract
The Yukawa one-component plasma (OCP) model is a paradigm for describing plasmas that contain one component of interest and one or more other components that can be treated as a neutralizing, screening background. In appropriately scaled units, interactions are characterized entirely by a screening parameter, κ. As a result, systems of similar κ show the same dynamics, regardless of the underlying parameters (e.g., density and temperature). We demonstrate this behavior using ultracold neutral plasmas (UNPs) created by photoionizing a cold (T≤10 mK) gas. The ions in UNP systems are well described by the Yukawa model, with the electrons providing the screening. Creation of the plasma through photoionization can be thought of as a rapid quench of the interaction potential from κ=∞ to a final κ value set by the electron density and temperature. We demonstrate experimentally that the postquench dynamics are universal in κ over a factor of 30 in density and an order of magnitude in temperature. Results are compared with molecular-dynamics simulations. We also demonstrate that features of the postquench kinetic energy evolution, such as disorder-induced heating and kinetic-energy oscillations, can be used to determine the plasma density and the electron temperature.
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Affiliation(s)
- T K Langin
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA
| | - T Strickler
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA
| | - N Maksimovic
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA
| | - P McQuillen
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA
| | - T Pohl
- Max Planck Institute for Complex Systems, Dresden, Germany
| | - D Vrinceanu
- Department of Physics, Texas Southern University, Houston, Texas 77004, USA
| | - T C Killian
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA
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8
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Strongly-coupled plasmas formed from laser-heated solids. Sci Rep 2015; 5:15693. [PMID: 26503293 PMCID: PMC4621604 DOI: 10.1038/srep15693] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2015] [Accepted: 10/01/2015] [Indexed: 11/09/2022] Open
Abstract
We present an analysis of ion temperatures in laser-produced plasmas formed from solids with different initial lattice structures. We show that the equilibrium ion temperature is limited by a mismatch between the initial crystallographic configuration and the close-packed configuration of a strongly-coupled plasma, similar to experiments in ultracold neutral plasmas. We propose experiments to demonstrate and exploit this crystallographic heating in order to produce a strongly coupled plasma with a coupling parameter of several hundred.
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Lyon M, Bergeson SD, Diaw A, Murillo MS. Using higher ionization states to increase Coulomb coupling in an ultracold neutral plasma. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2015; 91:033101. [PMID: 25871218 DOI: 10.1103/physreve.91.033101] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2014] [Indexed: 06/04/2023]
Abstract
We report measurements and simulations of the time-evolving rms velocity distribution in an ultracold neutral plasma. A strongly coupled ultracold neutral Ca+ plasma is generated by photoionizing laser-cooled atoms close to threshold. A fraction of these ions is then promoted to the second ionization state to form a mixed Ca+-Ca2+ plasma. By varying the time delay between the first and the second ionization events, a minimum in ion heating is achieved. We show that the Coulomb strong-coupling parameter Γ increases by a factor of 1.4 to a maximum value of 3.6. A pure Ca2+ plasma would have Γ=6.8, moving these strongly coupled systems closer to the regime of liquid-like correlations.
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Affiliation(s)
- M Lyon
- Department of Physics and Astronomy, Brigham Young University, Provo, Utah 84602, USA
| | - S D Bergeson
- Department of Physics and Astronomy, Brigham Young University, Provo, Utah 84602, USA
| | - A Diaw
- New Mexico Consortium, Los Alamos, New Mexico 87544, USA
| | - M S Murillo
- New Mexico Consortium, Los Alamos, New Mexico 87544, USA
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Sadeghi H, Kruyen A, Hung J, Gurian JH, Morrison JP, Schulz-Weiling M, Saquet N, Rennick CJ, Grant ER. Dissociation and the development of spatial correlation in a molecular ultracold plasma. PHYSICAL REVIEW LETTERS 2014; 112:075001. [PMID: 24579607 DOI: 10.1103/physrevlett.112.075001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2013] [Indexed: 06/03/2023]
Abstract
Penning ionization initiates the evolution of a dense molecular Rydberg gas to plasma. This process selects for pairs of excited molecules separated by a distance of two Rydberg orbital diameters or less. The deactivated Penning partners predissociate, depleting the leading edge of the distribution of nearest-neighbor distances. For certain density and orbital radii, this sequence of events can form a plasma in which large distances separate a disproportionate fraction of the ions. Experimental results and model calculations suggest that the reduced potential energy of this Penning lattice significantly affects the development of strong coupling in an ultracold plasma.
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Affiliation(s)
- H Sadeghi
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia V6 T 1Z3, Canada
| | - A Kruyen
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia V6 T 1Z3, Canada
| | - J Hung
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia V6 T 1Z3, Canada
| | - J H Gurian
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia V6 T 1Z3, Canada
| | - J P Morrison
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia V6 T 1Z3, Canada
| | - M Schulz-Weiling
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia V6 T 1Z3, Canada
| | - N Saquet
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia V6 T 1Z3, Canada
| | - C J Rennick
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia V6 T 1Z3, Canada
| | - E R Grant
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia V6 T 1Z3, Canada
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Bannasch G, Killian TC, Pohl T. Strongly coupled plasmas via Rydberg blockade of cold atoms. PHYSICAL REVIEW LETTERS 2013; 110:253003. [PMID: 23829735 DOI: 10.1103/physrevlett.110.253003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2013] [Indexed: 06/02/2023]
Abstract
We propose and analyze a new scheme to produce ultracold neutral plasmas deep in the strongly coupled regime. The method exploits the interaction blockade between cold atoms excited to high-lying Rydberg states and therefore does not require substantial extensions of current ultracold plasma experiments. Extensive simulations reveal a universal behavior of the resulting Coulomb coupling parameter, providing a direct connection between the physics of strongly correlated Rydberg gases and ultracold plasmas. The approach is shown to reduce currently accessible temperatures by more than an order of magnitude, which opens up a new regime for ultracold plasma research and cold ion-beam applications with readily available experimental techniques.
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Affiliation(s)
- G Bannasch
- Max Planck Institute for the Physics of Complex Systems, D-01187 Dresden, Germany
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Bannasch G, Castro J, McQuillen P, Pohl T, Killian TC. Velocity relaxation in a strongly coupled plasma. PHYSICAL REVIEW LETTERS 2012; 109:185008. [PMID: 23215292 DOI: 10.1103/physrevlett.109.185008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2012] [Indexed: 06/01/2023]
Abstract
Collisional relaxation of Coulomb systems is studied in the strongly coupled regime. We use an optical pump-probe approach to manipulate and monitor the dynamics of ions in an ultracold neutral plasma, which allows direct measurement of relaxation rates in a regime where common Landau-Spitzer theory breaks down. Numerical simulations confirm the experimental results and display non-Markovian dynamics at early times.
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Affiliation(s)
- G Bannasch
- Max Planck Institute for the Physics of Complex Systems, D-01187 Dresden, Germany
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Heilmann N, Peatross JB, Bergeson SD. "Ultracold" neutral plasmas at room temperature. PHYSICAL REVIEW LETTERS 2012; 109:035002. [PMID: 22861862 DOI: 10.1103/physrevlett.109.035002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2012] [Indexed: 06/01/2023]
Abstract
We report a measurement of the electron temperature in a plasma generated by a high-intensity laser focused into a jet of neon. The 15 eV electron temperature is determined using an analytic solution of the plasma equations assuming local thermodynamic equilibrium, initially developed for ultracold neutral plasmas. We show that this analysis method accurately reproduces more sophisticated plasma simulations in our temperature and density range. While our plasma temperatures are far outside the typical "ultracold" regime, the ion temperature is determined by the plasma density through disorder-induced heating just as in ultracold neutral plasma experiments. Based on our results, we outline a pathway for achieving a strongly coupled neutral laser-produced plasma that even more closely resembles ultracold neutral plasma conditions.
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Affiliation(s)
- N Heilmann
- Department of Physics and Astronomy, Brigham Young University, Provo, Utah 84602, USA
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14
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Twedt KA, Rolston SL. Electronic detection of collective modes of an ultracold plasma. PHYSICAL REVIEW LETTERS 2012; 108:065003. [PMID: 22401078 DOI: 10.1103/physrevlett.108.065003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2011] [Indexed: 05/31/2023]
Abstract
Using a new technique to directly detect current induced on a nearby electrode, we measure plasma oscillations in ultracold plasmas, which are influenced by the inhomogeneous and time-varying density and changing neutrality. Electronic detection avoids heating and evaporation dynamics associated with previous measurements and allows us to test the importance of the plasma neutrality. We apply dc and pulsed electric fields to control the electron loss rate and find that the charge imbalance of the plasma has a significant effect on the resonant frequency, in excellent agreement with recent predictions suggesting coupling to an edge mode.
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Affiliation(s)
- K A Twedt
- Joint Quantum Institute and Department of Physics, University of Maryland, College Park, Maryland 20742, USA
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15
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Bergeson SD, Robicheaux F. Recombination fluorescence in ultracold neutral plasmas. PHYSICAL REVIEW LETTERS 2008; 101:073202. [PMID: 18764531 DOI: 10.1103/physrevlett.101.073202] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2007] [Revised: 05/09/2008] [Indexed: 05/26/2023]
Abstract
We present the first measurements and simulations of recombination fluorescence from ultracold neutral calcium plasmas. This method probes three-body recombination at times less than 1 micros, shorter than previously published time scales. For the lowest initial electron temperatures, the recombination rate scales with the density as n0(2.2), significantly slower than the predicted n0(3). Recombination fluorescence opens a new diagnostic window in ultracold plasmas. In most cases it probes deeply bound level populations that depend critically on electron energetics. However, a perturbation in the calcium 4snd Rydberg series allows our fluorescence measurements to probe the population in weakly bound levels that result just after recombination.
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Affiliation(s)
- S D Bergeson
- Department of Physics and Astronomy, Brigham Young University, Provo, Utah 84602, USA
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16
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Pohl T, Vrinceanu D, Sadeghpour HR. Rydberg atom formation in ultracold plasmas: small energy transfer with large consequences. PHYSICAL REVIEW LETTERS 2008; 100:223201. [PMID: 18643419 DOI: 10.1103/physrevlett.100.223201] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2007] [Revised: 03/21/2008] [Indexed: 05/26/2023]
Abstract
We present extensive Monte Carlo calculations of electron-impact-induced transitions between highly excited Rydberg states and provide accurate rate coefficients. For moderate energy changes, our calculations confirm the widely applied expressions in P. Mansbach and J. Keck [Phys. Rev. 181, 275 (1969)] but reveal strong deviations at small energy transfer. Simulations of ultracold plasmas demonstrate that these corrections significantly impact the short-time dynamics of three-body Rydberg atom formation. The improved rate coefficients yield quantitative agreement with recent ultracold plasma experiments.
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Affiliation(s)
- T Pohl
- ITAMP, Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, Massachusetts 02138, USA
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