Enhanced Control and Reproducibility of Non-Neutral Plasmas.

The simultaneous control of the density and particle number of non-neutral plasmas confined in Penning-Malmberg traps is demonstrated. Control is achieved by setting the plasma's density by applying a rotating electric field while simultaneously fixing its axial potential via evaporative cooling. This novel method is particularly useful for stabilizing positron plasmas, as the procedures used to collect positrons from radioactive sources typically yield plasmas with variable densities and particle numbers; it also simplifies optimization studies that require plasma parameter scans. The reproducibility achieved by applying this technique to the positron and electron plasmas used by the ALPHA antihydrogen experiment at CERN, combined with other developments, contributed to a 10-fold increase in the antiatom trapping rate.

[1]  C. J. Baker,et al.  Antihydrogen accumulation for fundamental symmetry tests , 2017, Nature Communications.

[2]  C. J. Baker,et al.  Observation of the hyperfine spectrum of antihydrogen , 2017, Nature.

[3]  C. J. Baker,et al.  Observation of the 1S–2S transition in trapped antihydrogen , 2016, Nature.

[4]  C. Surko,et al.  Formation mechanisms and optimization of trap-based positron beams , 2016 .

[5]  T. Pedersen,et al.  Recent status of A Positron-Electron Experiment (APEX) , 2014 .

[6]  E. Gilson.  Excitation of Transverse Dipole and Quadrupole Modes in a Pure Ion Plasma in a Linear Paul Trap to Study Collective Processes in Intense Beams , 2012 .

[7]  Berkeley,et al.  Confinement of antihydrogen for 1,000 seconds , 2011, 1104.4982.

[8]  J. Wurtele,et al.  Autoresonant excitation of antiproton plasmas. , 2011, Physical review letters.

[9]  C. Surko,et al.  Electrostatic beams from tailored plasmas in a Penning–Malmberg trap , 2010 .

[10]  J. Wurtele,et al.  Evaporative cooling of antiprotons to cryogenic temperatures. , 2010, Physical review letters.

[11]  J S Hangst,et al.  Antiproton, positron, and electron imaging with a microchannel plate/phosphor detector. , 2009, The Review of scientific instruments.

[12]  C. Surko,et al.  Creation of finely focused particle beams from single-component plasmas , 2008 .

[13]  C. Surko,et al.  Radial compression and torque-balanced steady states of single-component plasmas in Penning-Malmberg traps , 2006 .

[14]  C. Surko,et al.  Torque-balanced high-density steady states of single-component plasmas. , 2005, Physical review letters.

[15]  J. Fajans.  Non-neutral plasma equilibria, trapping, separatrices, and separatrix crossing in magnetic mirrors , 2003 .

[16]  A. Marshall.  Milestones in fourier transform ion cyclotron resonance mass spectrometry technique development , 2000 .

[17]  Greaves,et al.  Inward transport and compression of a positron plasma by a rotating electric field , 2000, Physical review letters.

[18]  E. M. Hollmann,et al.  STEADY-STATE CONFINEMENT OF NON-NEUTRAL PLASMAS BY ROTATING ELECTRIC FIELDS , 1997 .

[19]  David J. Wineland,et al.  Non‐neutral ion plasmas and crystals, laser cooling, and atomic clocks* , 1994 .

[20]  J. Fajans,et al.  Collapse and winding of an asymmetric annulus of vorticity , 1993, Journal of Fluid Mechanics.

[21]  Murphy,et al.  Positron trapping in an electrostatic well by inelastic collisions with nitrogen molecules. , 1992, Physical review. A, Atomic, molecular, and optical physics.

[22]  K. Fine,et al.  Experiments on vortex dynamics in pure electron plasmas , 1990 .

[23]  T. M. O'Neil,et al.  Finite length thermal equilibria of a pure electron plasma column , 1979 .

[24]  John W. V. Storey,et al.  The ALPHA antihydrogen trapping apparatus , 2014 .

[25]  N. Tantalo,et al.  ALPHA Collaboration , 1999 .

[26]  I. Miyazaki,et al.  AND T , 2022 .