Diocotron Drift Mode Suppression for Increased Particle Transfer in a Multi Cell Trap
ORAL · Invited
Abstract
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.
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.
*This work was funded by DFG (Grant Nos. SCHW 401/23-1, Hu 978/15-1 and PE 2655/1-1) and ERC (Grant No. 741322). JRD is funded by U.S. DOE (Grant No. DE-SC0019271).
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Publication: [1] Stoneking, M. R., et al. "A new frontier in laboratory physics: Magnetized electron–positron plasmas." Journal of Plasma Physics 86.6 (2020): 155860601.
[2] Singer, M., et al. "Multi-cell trap development towards the accumulation and confinement of large quantities of positrons" Journal of Plasma Physics (2023), accepted.
[3] Hurst, N. C., et al. "Electron plasma orbits from competing diocotron drifts." Physical Review Letters 113.2 (2014): 025004.
Presenters
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Martin Singer
- Max Planck Institute for Plasma Physics