EPS 2019

P1.4008 Optimizing injection of positrons into a magnetic dipole trap

8 Jul 2019, 14:00

2h

Building U6 (University of Milano-Bicocca UNIMIB)

BSAP Poster P1

Speaker

S. Nißl (EPS 2019)

Description

See the full abstract here:
http://ocs.ciemat.es/EPS2019ABS/pdf/P1.4008.pdf

In a pair plasma, the two oppositely charged particle species have a mass ratio of one. This property is predicted to have significant influence on the behavior of such a plasma including extraordinary stability characteristics [1]. APEX (A Positron-Electron Experiment) aims to create this kind of plasma in a magnetic dipole trap. Because the number of available positrons is the limiting factor to reach plasma densities, it is essential to be able to inject positrons as efficiently as possible into the confinement volume. Unfortunately, the physics that confines charged particles in the dipole also makes their injection from the outside challenging. Recently, lossless injection [2] of the steady positron beam of NEPOMUC [3] into the confinement volume of the magnetic field of a supported permanent magnet was achieved by utilizing the E◊B guiding-center drift and optimizing the electrostatic potentials of the surrounding electrodes. Moreover, confinement times exceeding 1s were observed [4]. These findings were accompanied and reproduced by single-particle simulations. On this basis, numerical studies for the next-generation experiments were carried out. The results promise improved confinement times and suggest that the accumulation of positrons from multiple pulses is potentially feasible in the dipole.

1. P. Helander, Microstability of Magnetically Confined Electron-Positron Plasmas, Phys. Rev. Lett. 113, 135003 (2014).
2. E.V. Stenson, S. Nifll, U. Hergenhahn, J. Horn-Stanja, M. Singer, H. Saitoh, T. Sunn Pedersen, J.R. Danielson, M.R. Stoneking, M. Dickmann, and C. Hugenschmidt, Lossless Positron Injection into a Magnetic Dipole Trap, Phys. Rev. Lett. 121, 235005 (2018).
3. C. Hugenschmidt, C. Piochacz, M. Reiner, and K. Schreckenbach, The NEPOMUC upgrade and advanced positron beam experiments, New J. Phys. 14, 055027 (2012).
4. J. Horn-Stanja, S. Nifll, U. Hergenhahn, T. Sunn Pedersen, H. Saitoh, E.V. Stenson, M. Dickmann, C. Hugenschmidt, M. Singer, M.R. Stoneking, and J.R. Danielson, Confinement of Positrons Exceeding 1 s in a Supported Magnetic Dipole Trap, Phys. Rev. Lett. 121, 235003 (2018).