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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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2
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Amole C, Ashkezari MD, Baquero-Ruiz M, Bertsche W, Butler E, Capra A, Cesar CL, Chapman S, Charlton M, Eriksson S, Fajans J, Friesen T, Fujiwara MC, Gill DR, Gutierrez A, Hangst JS, Hardy WN, Hayden ME, Isaac CA, Jonsell S, Kurchaninov L, Little A, Madsen N, McKenna JTK, Menary S, Napoli SC, Nolan P, Olchanski K, Olin A, Povilus A, Pusa P, Rasmussen CØ, Robicheaux F, Sarid E, Silveira DM, Stracka S, So C, Thompson RI, Turner M, van der Werf DP, Wurtele JS, Zhmoginov A. Autoresonant-spectrometric determination of the residual gas composition in the ALPHA experiment apparatus. Rev Sci Instrum 2013; 84:065110. [PMID: 23822381 DOI: 10.1063/1.4811527] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Knowledge of the residual gas composition in the ALPHA experiment apparatus is important in our studies of antihydrogen and nonneutral plasmas. A technique based on autoresonant ion extraction from an electrostatic potential well has been developed that enables the study of the vacuum in our trap. Computer simulations allow an interpretation of our measurements and provide the residual gas composition under operating conditions typical of those used in experiments to produce, trap, and study antihydrogen. The methods developed may also be applicable in a range of atomic and molecular trap experiments where Penning-Malmberg traps are used and where access is limited.
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Affiliation(s)
- C Amole
- Department of Physics and Astronomy, York University, Toronto, Ontario M3J 1P3, Canada
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3
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Chen SN, d'Humières E, Lefebvre E, Romagnani L, Toncian T, Antici P, Audebert P, Brambrink E, Cecchetti CA, Kudyakov T, Pipahl A, Sentoku Y, Borghesi M, Willi O, Fuchs J. Focusing dynamics of high-energy density, laser-driven ion beams. Phys Rev Lett 2012; 108:055001. [PMID: 22400936 DOI: 10.1103/physrevlett.108.055001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2011] [Indexed: 05/31/2023]
Abstract
The dynamics of the focusing of laser-driven ion beams produced from concave solid targets was studied. Most of the ion beam energy is observed to converge at the center of the cylindrical targets with a spot diameter of 30 μm, which can be very beneficial for applications requiring high beam energy densities. Also, unbalanced laser irradiation does not compromise the focusability of the beam. However, significant filamentation occurs during the focusing, potentially limiting the localization of the energy deposition region by these beams at focus. These effects could impact the applicability of such high-energy density beams for applications, e.g., in proton-driven fast ignition.
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Affiliation(s)
- S N Chen
- LULI, École Polytechnique, CNRS, CEA, UPMC, route de Saclay, 91128 Palaiseau, France
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Andresen GB, Ashkezari MD, Baquero-Ruiz M, Bertsche W, Bowe PD, Butler E, Cesar CL, Chapman S, Charlton M, Deller A, Eriksson S, Fajans J, Friesen T, Fujiwara MC, Gill DR, Gutierrez A, Hangst JS, Hardy WN, Hayden ME, Humphries AJ, Hydomako R, Jonsell S, Madsen N, Menary S, Nolan P, Olin A, Povilus A, Pusa P, Robicheaux F, Sarid E, Silveira DM, So C, Storey JW, Thompson RI, van der Werf DP, Wurtele JS, Yamazaki Y. Centrifugal separation and equilibration dynamics in an electron-antiproton plasma. Phys Rev Lett 2011; 106:145001. [PMID: 21561196 DOI: 10.1103/physrevlett.106.145001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2010] [Indexed: 05/30/2023]
Abstract
Charges in cold, multiple-species, non-neutral plasmas separate radially by mass, forming centrifugally separated states. Here, we report the first detailed measurements of such states in an electron-antiproton plasma, and the first observations of the separation dynamics in any centrifugally separated system. While the observed equilibrium states are expected and in agreement with theory, the equilibration time is approximately constant over a wide range of parameters, a surprising and as yet unexplained result. Electron-antiproton plasmas play a crucial role in antihydrogen trapping experiments.
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Affiliation(s)
- G B Andresen
- Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C, Denmark
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5
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Andresen GB, Ashkezari MD, Baquero-Ruiz M, Bertsche W, Bowe PD, Butler E, Cesar CL, Chapman S, Charlton M, Deller A, Eriksson S, Fajans J, Friesen T, Fujiwara MC, Gill DR, Gutierrez A, Hangst JS, Hardy WN, Hayden ME, Humphries AJ, Hydomako R, Jenkins MJ, Jonsell S, Jørgensen LV, Kurchaninov L, Madsen N, Menary S, Nolan P, Olchanski K, Olin A, Povilus A, Pusa P, Robicheaux F, Sarid E, Nasr SSE, Silveira DM, So C, Storey JW, Thompson RI, van der Werf DP, Wurtele JS, Yamazaki Y. Trapped antihydrogen. Nature 2010; 468:673-6. [DOI: 10.1038/nature09610] [Citation(s) in RCA: 265] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2010] [Accepted: 10/27/2010] [Indexed: 11/09/2022]
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Higaki H, Fukata K, Ito K, Okamoto H, Gomberoff K. Density and potential profiles of non-neutral electron plasmas in a magnetic mirror field. Phys Rev E Stat Nonlin Soft Matter Phys 2010; 81:016401. [PMID: 20365479 DOI: 10.1103/physreve.81.016401] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2009] [Indexed: 05/29/2023]
Abstract
Low-energy non-neutral electron plasmas were confined with an electrostatic potential and a magnetic mirror field of the mirror ratio up to 5. Using a conventional phosphor screen and the unique multiring trap, both radial and axial density profiles of plasmas were measured. With the present experimental parameters, it was confirmed that a plasma density increased at higher field with an electrostatic confinement and that it decreased at higher field with a magnetic mirror confinement. The electrostatic potentials along the magnetic field were estimated with computer simulations.
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Affiliation(s)
- H Higaki
- Advanced Sciences of Matter, Hiroshima University, Higashi-Hiroshima, Hiroshima, Japan
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7
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Andresen GB, Bertsche W, Bowe PD, Bray CC, Butler E, Cesar CL, Chapman S, Charlton M, Fajans J, Fujiwara MC, Gill DR, Hangst JS, Hardy WN, Hayano RS, Hayden ME, Humphries AJ, Hydomako R, Jørgensen LV, Kerrigan SJ, Kurchaninov L, Lambo R, Madsen N, Nolan P, Olchanski K, Olin A, Povilus AP, Pusa P, Sarid E, Seif El Nasr S, Silveira DM, Storey JW, Thompson RI, van der Werf DP, Yamazaki Y. Antiproton, positron, and electron imaging with a microchannel plate/phosphor detector. Rev Sci Instrum 2009; 80:123701. [PMID: 20073120 DOI: 10.1063/1.3266967] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
A microchannel plate (MCP)/phosphor screen assembly has been used to destructively measure the radial profile of cold, confined antiprotons, electrons, and positrons in the ALPHA experiment, with the goal of using these trapped particles for antihydrogen creation and confinement. The response of the MCP to low energy (10-200 eV, <1 eV spread) antiproton extractions is compared to that of electrons and positrons.
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Barth I, Friedland L, Sarid E, Shagalov AG. Autoresonant transition in the presence of noise and self-fields. Phys Rev Lett 2009; 103:155001. [PMID: 19905645 DOI: 10.1103/physrevlett.103.155001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2009] [Indexed: 05/28/2023]
Abstract
A sharp threshold for resonant capture of an ensemble of trapped particles driven by chirped frequency oscillations is analyzed. It is shown that at small temperatures T, the capture probability versus driving amplitude is a smoothed step function with the step location and width scaling as alpha(3/4) (alpha being the chirp rate) and (alphaT)(1/2), respectively. Strong repulsive self-fields reduce the width of the threshold considerably, as the ensemble forms a localized autoresonant macroparticle.
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Affiliation(s)
- I Barth
- Racah Institute of Physics, Hebrew University of Jerusalem, Jerusalem 91904, Israel.
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Bovino S, Zhang P, Kharchenko V, Dalgarno A. Trapping hydrogen atoms from a neon-gas matrix: A theoretical simulation. J Chem Phys 2009; 131:054302. [DOI: 10.1063/1.3180822] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
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Fujiwara MC, Amoretti M, Amsler C, Bonomi G, Bouchta A, Bowe PD, Canali C, Carraro C, Cesar CL, Charlton M, Doser M, Fontana A, Funakoshi R, Genova P, Hangst JS, Hayano RS, Jørgensen LV, Kellerbauer A, Lagomarsino V, Landua R, Lodi-Rizzini E, Macri M, Madsen N, Manuzio G, Mitchard D, Montagna P, Pruys H, Regenfus C, Rotondi A, Testera G, Variola A, Venturelli L, van der Werf DP, Yamazaki Y, Zurlo N. Temporally controlled modulation of antihydrogen production and the temperature scaling of antiproton-positron recombination. Phys Rev Lett 2008; 101:053401. [PMID: 18764390 DOI: 10.1103/physrevlett.101.053401] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2007] [Indexed: 05/26/2023]
Abstract
We demonstrate temporally controlled modulation of cold antihydrogen production by periodic RF heating of a positron plasma during antiproton-positron mixing in a Penning trap. Our observations have established a pulsed source of atomic antimatter, with a rise time of about 1 s, and a pulse length ranging from 3 to 100 s. Time-sensitive antihydrogen detection and positron plasma diagnostics, both capabilities of the ATHENA apparatus, allowed detailed studies of the pulsing behavior, which in turn gave information on the dependence of the antihydrogen production process on the positron temperature T. Our data are consistent with power law scaling T (-1.1+/-0.5) for the production rate in the high temperature regime from approximately 100 meV up to 1.5 eV. This is not in accord with the behavior accepted for conventional three-body recombination.
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Affiliation(s)
- M C Fujiwara
- TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia, Canada.
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11
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Andresen GB, Bertsche W, Bowe PD, Bray CC, Butler E, Cesar CL, Chapman S, Charlton M, Fajans J, Fujiwara MC, Funakoshi R, Gill DR, Hangst JS, Hardy WN, Hayano RS, Hayden ME, Hydomako R, Jenkins MJ, Jørgensen LV, Kurchaninov L, Lambo R, Madsen N, Nolan P, Olchanski K, Olin A, Povilus A, Pusa P, Robicheaux F, Sarid E, El Nasr SS, Silveira DM, Storey JW, Thompson RI, van der Werf DP, Wurtele JS, Yamazaki Y. Compression of antiproton clouds for antihydrogen trapping. Phys Rev Lett 2008; 100:203401. [PMID: 18518531 DOI: 10.1103/physrevlett.100.203401] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2007] [Indexed: 05/26/2023]
Abstract
Control of the radial profile of trapped antiproton clouds is critical to trapping antihydrogen. We report the first detailed measurements of the radial manipulation of antiproton clouds, including areal density compressions by factors as large as ten, by manipulating spatially overlapped electron plasmas. We show detailed measurements of the near-axis antiproton radial profile and its relation to that of the electron plasma.
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Affiliation(s)
- G B Andresen
- Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C, Denmark
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12
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Gabrielse G, Larochelle P, Le Sage D, Levitt B, Kolthammer WS, McConnell R, Richerme P, Wrubel J, Speck A, George MC, Grzonka D, Oelert W, Sefzick T, Zhang Z, Carew A, Comeau D, Hessels EA, Storry CH, Weel M, Walz J. Antihydrogen production within a Penning-Ioffe trap. Phys Rev Lett 2008; 100:113001. [PMID: 18517780 DOI: 10.1103/physrevlett.100.113001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2007] [Indexed: 05/26/2023]
Abstract
Slow antihydrogen (H) is produced within a Penning trap that is located within a quadrupole Ioffe trap, the latter intended to ultimately confine extremely cold, ground-state H[over ] atoms. Observed H[over ] atoms in this configuration resolve a debate about whether positrons and antiprotons can be brought together to form atoms within the divergent magnetic fields of a quadrupole Ioffe trap. The number of detected H atoms actually increases when a 400 mK Ioffe trap is turned on.
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Affiliation(s)
- G Gabrielse
- Department of Physics, Harvard University, Cambridge, MA 02138, USA.
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Abstract
We report the cooling of an atomic ensemble with light, where each atom scatters only a single photon on average. This is a general method that does not require a cycling transition and can be applied to atoms or molecules that are magnetically trapped. We discuss the application of this new approach to the cooling of hydrogenic atoms for the purpose of precision spectroscopy and fundamental tests.
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Affiliation(s)
- Gabriel N Price
- Center for Nonlinear Dynamics and Department of Physics, The University of Texas at Austin, Austin, TX 78712, USA
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14
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Abstract
Experimental conditions have recently been reported [G. Andresen, Phys. Rev. Lett. 98, 023402 (2007)] that are relevant to the prospect of trapping antihydrogen atoms. An analysis of the experimental conditions indicates that positron space charge can have an important effect. The fraction of antiprotons that have an energy suitable for antihydrogen trapping can be reduced by drifts caused by the presence of positron space charge.
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Affiliation(s)
- C A Ordonez
- Department of Physics, University of North Texas, Denton, Texas 76203, USA
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15
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Higaki H, Ito K, Saiki W, Omori Y, Okamoto H. Properties of non-neutral electron plasmas confined with a magnetic mirror field. Phys Rev E Stat Nonlin Soft Matter Phys 2007; 75:066401. [PMID: 17677366 DOI: 10.1103/physreve.75.066401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2007] [Indexed: 05/16/2023]
Abstract
A low energy non-neutral electron plasma was confined with a magnetic mirror field and an electrostatic potential to investigate the basic confinement properties of a simple magnetic mirror trap. The mirror ratio of the magnetic field was increased up to 5. As expected the confinement time became longer as a function of the mirror ratio. The axially integrated radial density profiles in equilibrium were measured and compared with a theoretical model. The axial electrostatic oscillations of a confined electron plasma were also observed.
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Affiliation(s)
- H Higaki
- Advanced Sciences of Matter, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima, 739-8530, Japan
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