Diocotron Drift Mode Suppression for Increased Particle Transfer in a Multi Cell Trap*

For the creation of a positron-electron (pair) plasma the A Positron Electron eXperiment (APEX) collaboration needs large quantities of positrons. To accumulate many positron is an experimentally challenging task [1]. To achieve this task, we have designed and constructed a new prototype multi cell Penning-Malmberg trap (MCT) [2]. This MCT includes a master cell, and three storage cells (one on-axis, and two off-axis). With this device we will test and improve the plasma transfer to the off-axis cells while mitigating losses. The goal is to transfer and stack multiple plasma pulses in one (or more) off-axis trap.

 

In this contribution, we discuss the dynamics during the transport to the off-axis cells. These dynamics are dominated by competing diocotron drift modes [3] that can lead to significant particle losses. We present techniques to suppress these modes that mitigate losses and center the plasma in the off-axis cells. With these techniques, we significantly improved the transfer. In addition, we were able to demonstrate the first consecutive transfer and confinement in two different off-axis cells. The confinement in multiple off-axis traps is a milestone for the future use of a MCT at the NEPOMUC positron source in Munich.