The Design of KSTAR FM reflectometer Seong-Heon Seo National Fusion Research Institute (NFRI)

Contents KSTAR Design Schedule

KSTAR Tokamak R=1.8 m, a = 0.5 m PF and TF (B T =3.5 T) Coils = Nb 3 Sn I P = 2 MA, 5 min Bad accessibility

First Plasma in KSTAR B T = 1.5 T 2 nd Harmonic ECH preionization (84 GHz, 300 kW) Plasma current ~ 100 kA, 0.7 s Magnetic Diagnostics Interferometer (1 ch) ECE (8 ch) H α, Filter Scope CCD Camera (1 kHz)

2 nd Campaign ( ) B T = 3.0 T Plasma current ~ 300 kA, 2 s Fundamental Harmonic ECH preionization (84 GHz, 500 kW) Magnetic Diagnostics Reflectometer (2 ch, Q and V Band) ECE (32 ch) Bolometer X-ray Crystal Spectroscopy (XCS) Operation Parameter New Diagnostics

Frequency Selection Plasma type Low field High field Case ICase II n 0 (x10 14 cm -3 ) B 0 (T) f x_c f ce 2f ce f pe Plasma type Low fieldHigh field Case ICase II Wave modeOXOXOX Frequency range of probing signals [GHz] Max. accessible position r of cutoff layer (cm)

Q and V Band Reflectometer

Q Band (33-50 GHz) Mixer, MQ-U SpaceK Labs Low pass filter LPF SpaceK Labs 25 dB Low pass filter FLP-22-R0000 Militech 40 dB Transition TWT-28-R22R0 Militech Frequency multiplier AQ-4XW-10 SpaceK Labs

V Band (50-75 GHz) Mixer, MV-U SpaceK Labs Low pass filter LPF SpaceK Labs 25 dB Low pass filter FLP-15-R0000 Militech 40 dB Transition TWT-28-R15R0 Militech Frequency multiplier AMC-15-RFH00 Militech

Antenna design

Diagnostics on G-port 1.Interferometer (2008) --> FIR on H-port 2.Reflectometer (2009) 3.MIR (2012) POSTEC  TEXTOR 5 frequencies

Interferometer in G-port

Antenna of Interferometer

G Port

Antenna design

Engineering Design

DETAIL VIEW

Frequency Selection Plasma type Low field High field Case ICase II n 0 (x10 14 cm -3 ) B 0 (T) f x_c f ce 2f ce f pe Plasma type Low fieldHigh field Case ICase II Wave modeOXOXOX Frequency range of probing signals [GHz] Max. accessible position r of cutoff layer (cm)

W and D Band (B t = 3.5 T) Too expensive

Summary and Schedule 2 nd campaign: - Q (33-50 GHz) and V (50-75 GHz) Band in X-mode - B T = 1.5 T 3 rd campaign: - B T = 3.0 T - W Band ( GHz) in X-mode D BandQ and V Band in O-mode Square waveguide + Twister Cross Polarization