Micro-Faraday cup matrix detector for ion beam measurements in fusion plasmas

• Main Authors: Réfy, Dániel Imre, Zoletnik, Sándor, Dunai, Dániel, Anda, Gábor, Lampert, Máté, Hegedűs, Sándor, Nagy, Domonkos, Palánkai, Miklós, Kádi, Jenő, Leskó, Balázs, Hacek, Pavel, Weinzettl, Valdimir
• Format: Journal Article
• Language: English
• Published: 06-03-2019
• Subjects: Physics - Plasma Physics
• DOI: 10.48550/arxiv.1903.02239

Review of Scientific Instruments 90, 033501 (2019) Atomic Beam Probe (ABP) is an extension of the routinely used Beam Emission
Spectroscopy (BES) diagnostic for plasma edge current fluctuation measurement
at magnetically confined plasmas. Beam atoms ionized by the plasma are directed
to a curved trajectory by the magnetic field and may be detected close to the
wall of the device. The arrival location and current distribution of the ions
carry information about the plasma current distribution, the density profile
and the electric potential in the plasma edge. This paper describes a
micro-Faraday cup matrix detector for the measurement of the few microampere
ion current distribution close to the plasma edge. The device implements a
shallow Faraday cup matrix, produced by printed-circuit board technology.
Secondary electrons induced by the plasma radiation and the ion bombardment are
basically confined into the cups by the tokamak magnetic field. Additionally, a
double mask is installed in the front face to limit ion influx into the cups
and supplement secondary electron suppression. The setup was tested in detail
using a Lithium ion beam in the laboratory. Switching time, cross talk and
fluctuation sensitivity test results in the lab setup are presented, along with
the detector setup to be installed at the COMPASS tokamak.