Speaker
Helmut Faugel
(Max Planck Institute for Plasma Physics)
Description
The efficiency of heating and current drive systems is the key for a successful operation of fusion demonstration power plants like DEMO. In an earlier review article, overall efficiencies of H & CD systems were estimated at 20 – 30 % [1].
In this paper we present a breakdown of the overall efficiency for ICRF (ion cyclotron range of frequencies): 1) the technical efficiencies; 2) the interface efficiency (hardware/plasma), and 3) the efficiency power absorption in the central plasma named “heating efficiency”.
The technical efficiency of the generators includes all the subsystems like power supplies, air supply, CODAC, vacuum system, etc. and is today around 60 %. The pros and cons of solid-state amplifiers and the possible efficiency gains are reviewed. Losses for the matched and unmatched sections of the transmission lines are quantified. Losses in the antenna as a function of coupling impedance and antenna characteristics are discussed.
The interface efficiency is the ratio of the power to the plasma inside of the separatrix to the total power leaving the antenna. Power to the edge plasma is thus counted as loss. Most heating and current drive scenarios aim at strong absorption, coupling the power to the plasma core. In the high density, high temperature plasmas of large machines such as DEMO almost all wave power is absorbed in the plasma.
Whether the power centrally absorbed ends up in bulk plasma heating (“heating efficiency”) or driven current depends on the discharge parameters and the heating/current drive scenarios.
Experimental evidence in present machines shows that in heating scenarios the efficiency is 70-90%. This leads to an overall efficiency for heating in the range 40% to 55%.
We finally address the issue of current drive efficiency.
[1] Pamela et al. Fusion Engineering and Design, 84 (2009) 194-204
Co-authors
A. Messiaen
(LPP-ERM/KMS, Brussels, Belgium)
Dirk Van Eester
(LPP-ERM/KMS, Brussels, Belgium)
Helmut Faugel
(Max Planck Institute for Plasma Physics, Garching, Germany)
Helmut Funfgelder
(Max Planck Institute for Plasma Physics, Garching, Germany)
Jean-Marie Noterdaeme
(Max Planck Institute for Plasma Physics, Garching, Germany;Applied Physics Department, Ghent University, Ghent, Belgium)
Volodymyr Bobkov
(Max Planck Institute for Plasma Physics, Garching, Germany)