Creation and uses of positron plasmas*

Greaves, R. G.; Tinkle, M. D.; Surko, C. M.

doi:10.1063/1.870693

Cited by 256 publications

(139 citation statements)

References 33 publications

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“…The most important of these is the fact that the trap provided by the antiprotonic atom for the p is far from ideal: the lifetime in it is short (of the order of ns, in one very favorable case described in Sec. IV.B.5 below, in the s region), the antiproton interacts with the electrons and the nucleus of the host atom, and the atomic trap itself (i.e., the carrier atom) is far from being really isolated even in 11 Another well-known technique of a similar nature is cooling by collisions with buffer gas molecules (Greaves et al, 1994). This is out of the question for antiprotons, which would first be captured by the gas molecules and then annihilate, but as we shall see in Sec.…”

Section: B Microscopic Traps: Exotic Atomsmentioning

confidence: 99%

Forty years of antiprotons

Eades

Hartmann

1999

Rev. Mod. Phys.

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The discovery of the antiproton some 40 years ago and the almost synchronous fall of parity (P) and charge conjugation (C) symmetries were soon followed by the realization that CPT rather than C invariance is the fundamental symmetry connecting matter and antimatter, and that consequently any measurement of the antiproton's properties can be interpreted as a test of that symmetry. It is the latter view of the antiproton, as an object of study in its own right, rather than as a means to such other ends as the production of gauge bosons and meson resonances, that is presented here. The authors review the technical steps that have led from the handful of antiprotons observed by Chamberlain, Segrè , Wiegand, and Ypsilantis to the intense, high-quality beams available today and show how the state of rest and isolation required for high precision measurements of their properties can be achieved by confining them in electromagnetic traps or in their microscopic counterparts, exotic atoms. The test bench role of antiprotons and antihydrogen atoms for both CPT symmetry and the gravitational weak equivalence principle is discussed, and the body of experimental results obtained since 1955 critically reviewed from this standpoint. Future experiments are then discussed in the light of the closure of the CERN Low Energy Antiproton Ring (LEAR), its replacement in 1999 by the Antiproton Decelerator (AD), and the likely antiproton source at the Japan Hadron Facility.[S0034-6861(99)00401-8] CONTENTS

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Section: B Microscopic Traps: Exotic Atomsmentioning

confidence: 99%

Forty years of antiprotons

Eades

Hartmann

1999

Rev. Mod. Phys.

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“…Positrons have also been created in postdisruption plasmas in large tokamaks [18] through collisions between MeV electrons and thermal particles. The progress in the production of positron plasmas of the past two decades makes it possible to consider laboratory experiments on e-p plasmas [19][20][21].…”

Section: Introductionmentioning

confidence: 99%

Electromagnetic solitary pulses in a magnetized electron-positron plasma

2011

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A theory for large amplitude compressional electromagnetic solitary pulses in a magnetized electron-positron (e-p) plasma is presented. The pulses, which propagate perpendicular to the external magnetic field, are associated with the compression of the plasma density and the wave magnetic field. Here the solitary wave magnetic field pressure provides the restoring force, while the inertia comes from the equal mass electrons and positrons. The solitary pulses are formed due to a balance between the compressional wave dispersion arising from the curl of the inertial forces in Faradays law and the nonlinearities associated with the divergence of the electron and positron fluxes, the nonlinear Lorentz forces, the advection of the e-p fluids, and the nonlinear plasma current densities. The compressional solitary pulses can exist in a well-defined speed range above the Alfven speed. They can be associated with localized electromagnetic field excitations in magnetized laboratory and space plasmas composed of electrons and positrons.

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“…Nonneutral plasmas are studied in research to develop atomic clocks [8][9][10] , investigations of turbulence, nonlinear vortex dynamics, and instabilities in nearly-inviscid two-dimensional fluids [11][12][13][14][15][16][17][18] , research on particle transport across magnetic field lines in quiescent plasmas [19][20][21][22][23] , investigations of the properties of nonneutral plasmas in thermal equilibrium 24,25 , and in experiments to study the formation and confinement of positron plasmas [26][27][28] . Many of these experiments 8,13,19,[24][25][26] are performed at vacuum pressures in the range where background neutrals are observed to affect the plasma dynamical behavior and confinement properties.…”

mentioning

confidence: 99%

Expansion rate measurements at moderate pressure of non-neutral electron plasmas in the Electron Diffusion Gauge (EDG) experiment

et al. 2001

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Measurements of the expansion rate of pure-electron plasmas have been performed on the Electron Diffusion Gauge (EDG) device at background helium gas pressures in the 5×10 −8 Torr to 1×10 −5 Torr range, where plasma expansion due to electron-neutral collisions dominates over plasma expansion due to trap asymmetries. It is found that the expansion rate, defined as the time rate of change of the particles' mean-square radius, scales approximately linearly with pressure and inversely as the square of the magnetic field strength in this regime, in agreement with classical predictions.

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Creation and uses of positron plasmas*

Cited by 256 publications

References 33 publications

Forty years of antiprotons

Forty years of antiprotons

Electromagnetic solitary pulses in a magnetized electron-positron plasma

Expansion rate measurements at moderate pressure of non-neutral electron plasmas in the Electron Diffusion Gauge (EDG) experiment

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