Reducing the background temperature for cyclotron cooling in a cryogenic Penning–Malmberg trap

Abstract

Magnetized nonneutral plasma composed of electrons or positrons couples to the local microwave environment via cyclotron radiation. The equilibrium plasma temperature depends on the microwave energy density near the cyclotron frequency. Fine copper meshes and cryogenic microwave absorbing material were used to lower the effective temperature of the radiation environment in ASACUSA's Cusp trap, resulting in significantly reduced plasma temperature.

SDR, EVC, and SDREVC: Limitations and Extensions

“…The entrance and exit to the trap are screened by copper meshes (geometrical transparency = ) so that microwave radiation from the plasma cannot escape the cryogenic ultra-high vacuum region (Amsler et al. 2022). A typical plasma contains electrons, with length , radius and .…”

“…We use a Penning Malmberg trap (Malmberg & Driscoll 1980) with inner diameter 34 mm and magnetic field B ≈ 2 T. The entrance and exit to the trap are screened by copper meshes (geometrical transparency = 79 %) so that microwave radiation from the plasma cannot escape the 6 K cryogenic ultra-high vacuum region (Amsler et al 2022). A typical plasma contains N ∼ 10 7 electrons, with length L p ≈ 10 cm, radius r p ≈ 1 mm and n ∼ 10 8 cm −3 .…”