Title :
Measurement of RF transmission mode conversion due to waveguide thermal deformation using 170GHz gyrotron
Author :
Oda, Y. ; Kajiwara, K. ; Takahashi, K. ; Sakamoto, K.
Author_Institution :
Japan Atomic Energy Agency, Naka, Japan
Abstract :
The mode conversion by thermal deformation of the transmission line (TL) for electron cyclotron heating and current drive (EC H&CD) system caused by high-power long-pulse operation was studied. Mode contents in 40 m length TL test stand were measured and compared for before and after the 600 kW/169 s long-pulse operation. The mode content indicated that HE11 mode decreased by 10% and LP11 mode increased. The miter bend after the 12 m long horizontal straight section in TL was moved for 1.5 mm which deformed the short vertical waveguide section. The increased LP11 mode was converted from HE11 mode in the deformed waveguide. Although the TL kept high transmission efficiency under high-power long-range TL, mode conversion loss was significantly increased by thermal deformation of TL.
Keywords :
Tokamak devices; deformation; fusion reactor ignition; gyrotrons; plasma electromagnetic wave propagation; plasma filled waveguides; plasma radiofrequency heating; plasma toroidal confinement; plasma transport processes; ECCD system; ECH system; HE11 mode; LP11 mode; RF transmission mode conversion measurement; electron cyclotron current drive; electron cyclotron heating; frequency 170 GHz; gyrotron; high power long pulse operation; miter bend; power 600 kW; size 40 m; time 169 s; transmission line thermal deformation; waveguide thermal deformation; Gyrotrons; Power measurement; Presses; Radio frequency; Temperature distribution; Electron Cycletron Heating; Gyrotron; Long Pulse Operation; Transmission Line; Transmission Mode;
Conference_Titel :
Fusion Engineering (SOFE), 2011 IEEE/NPSS 24th Symposium on
Conference_Location :
Chicago, IL
Print_ISBN :
978-1-4577-0669-1
Electronic_ISBN :
1078-8891
DOI :
10.1109/SOFE.2011.6052328
