Speaker
Eve Virginia Stenson
Description
See the full Abstract at http://ocs.ciemat.es/EPS2018ABS/pdf/O4.407.pdf
Near-lossless positron injection into a dipole magnetic field
E. V. Stenson1,2 , U. Hergenhahn1 , S. Nissl1,2 , J. Horn-Stanja1 , H. Saitoh1,3 ,
T. Sunn Pedersen1,4 , M. R. Stoneking5 , M. Singer2 , M. Dickmann2 , C. Hugenschmidt2 ,
J. R. Danielson6 , C. M. Surko6
1 Max Planck Institute for Plasma Physics, Garching & Greifswald, Germany
2 Technische Universität München, Garching, Germany
3 The University of Tokyo, Kashiwa, Japan
4 University of Greifswald, Greifswald, Germany
5 Lawrence University, Appleton, WI, U.S.A.
6 University of California, San Diego, La Jolla, CA, U.S.A.
The nucleation and trapping of a small-Debye-length, electron-positron pair plasma in a
toroidal device will enable laboratory studies of these systems, which are predicted to have
novel properties significantly different from those of standard electron-ion plasmas — e.g., “re-
markable stability” [1]. A key prerequisite is the development of a scheme that enables efficient
injection of positrons from an external source, across flux surfaces, into the confinement region.
Previously, the NEPOMUC (NEutron-induced
POsitron source MUniCh) beam was injected with
beam line
38% efficiency into the dipole field of a supported per-
manent magnet and subsequently trapped [2]. Essen-
tially lossless injection into the same device has now
been demonstrated. This was accomplished by tailor-
ExB plate
ing positrons’ 3D guiding-center drift orbits via opti-
mization of electrostatic potentials applied to various
plates and wall segments, thereby producing localized
particle transport via the E × B drift. Experimental re-
magnet
sults are in excellent agreement with numerical simu-
lations (Fig. 1), enabling a comprehensive understand-
ing of the process. This paves the way for upcoming
experiments, in which dense pulses of positrons will
be injected into the dipole field of a levitated coil.
Figure 1: Simulated trajectories of a finite-
References temperature positron bunch being loss-
[1] P Helander. Phys. Rev. Lett., 113:135003, 2014.
lessly drift-injected into a dipole trap.
[2] H Saitoh, et al. New J. of Physics, 17(10):103038, 2015.
