Multipactor in High Power Radio-Frequency Systems for Nuclear Fusion

• Main Authors: Hillairet, Julien, Goniche, Marc, Fil, Nicolas, Belhaj, Mohamed, Puech, Jérôme
• Format: Journal Article
• Language: English
• Published: 10-10-2017
• Subjects: Physics - Plasma Physics
• DOI: 10.48550/arxiv.1710.03629

MULCOPIM (Multipactor, Corona and Passive Intermodulation), Apr
2017, Noordwijk, Netherlands. 2017 Magnetic confinement fusion researches are an approach to demonstrate the
feasibility of nuclear fusion power for energy production. In these
experiments, mega-watt range power Radio-Frequency waves, from tens of MHz to
hundreds of GHz, are injected into magnetically confined plasmas in order to
increase its temperature and to extend its duration. These RF systems are
subjected to the magnetic field environment of the experiments, ranging from
few tenth of Tesla to Tesla, and various orientations depending of their
locations. As these RF systems made of copper, silver or ceramics are located
in vacuum environments, they are subject to multipactor discharges. These
discharges are generally considered detrimental since they can lead to detuned
RF systems, limit the RF power transmission in the plasma and eventually damage
RF sources or components. In some case, especially in the MHz range of
frequency, multipactor discharges can be desired for vacuum conditioning. This
paper presents the various RF systems used in magnetic fusion experiments and
review the work performed in the fusion research community on multipactor
discharges for high power coaxial (MHz) and rectangular waveguides (GHz)
transmission lines, with their practical implications on power delivery into
the plasma.