Microwave Reflectometer
T. Tokuzawa
e-mail: tokuzawa@nifs.ac.jp

1.

Objective

Microwave reflectometers are measured a density fluctuation, an electron density profile, and a poloidal
flow velocity.

2. Apparatus
2.1. Specification
Currently, five types of reflectometer systems are working as follows:(1)Frequency comb Doppler reflectometerfrequency band : Ka-, U-band
objects : radial profile of density fluctuation, poloidal flow velocity
frequency response : 1MHz
spatial points : 16 points (fixed)(2)Frequency hopping Doppler reflectometerfrequency band : Ka-, V-band
objects : radial profile of density fluctuation, poloidal flow velocity
frequency response : 1MHz
spatial points : typically 20points (variable)(3) Ultra-short pulsed radar reflectometerfrequency band : X-, Ku-, Ka-, U-band
objects : radial profile of electron density
frequency response : 100kHz
spatial points : 40 points(4) Frequency fixed E-band heterodyne reflectometerfrequency : 65, 68 GHz
objects : density fluctuation monitor
frequency response : 1MHz
spatial points : 2 points(5) Frequency fixed Ka-band heterodyne reflectometerfrequency : 28, 30 GHzobjects : fast density fluctuation
frequency response : 2.5GHz
spatial points : 2 points

2.2.

Arrangement of all reflectometers(1) 3-O port (AD03) vertical direction(2) 9-O port (AD01, AD03, AD04) horizontal direction(3) 3-O port (AD02) vertical direction(4) 3-O port (AD01) horizontal direction(5) 3.5U port (BC03) vertical direction

Fig. 1. Toroidal location of Reflectometers.

- Cross sections are shown in Figs.2 and 3.

Fig. 2. 3-O port reflectoemter antenna arrangementultra-short pulsed radar reflectometer launches from high-field side.
fixed frequency reflectometer launches from low-filed side.

Fig. 3. 9-O port Doppler reflectometer3.

Operational requirement- In the case of an X-mode operation, the available magnetic field strength is limitted.

4.

Available data by “Retrieve”

4.1

Kaiseki-data server-“mwrm_9o_R_Iamp”: Fluctuation amplitude measured by Ka-band Frequency hopping Doppler
reflectometer at 9-O port
- “mwrm_9o_R_Iamp_fast”: High time resolution of above fluctuation amplitude measurement-“mwrm_9o_R_Vp”: Poloidal velocity by 9-O Ka-band Frequency hopping Doppler reflectometer- “mwrm_9o_R_Vp_fast”: High time resolution of above poloidal velocity measurement-“mwrm_comb_R_Iamp”: Fluctuation amplitude measured by Ka-band Frequency comb Doppler
reflectometer at 3-O port
- “mwrm_comb_R_Iamp_fast”: High time resolution of above fluctuation amplitude measurement-“mwrm_comb_R_Vp”: Poloidal velocity by 3-O Frequency comb Doppler reflectometer- “mwrm_comb_R_Vp_fast”: High time resolution of above poloidal velocity measurement

5.

Remarks

References[1] T. Tokuzawa, et al., “Developments of electron cyclotron emission spectroscopy and microwave
reflectometry on LHD”, Fusion Science and Technology, Vol. 58, No. 1 (2010) 364-374.
[2] T Tokuzawa, et al., “V-band frequency hopping microwave reflectometer in LHD”, Rev. Sci. Instrum.
Vol. 81 (2008) 10D906.
[3] T. Tokuzawa et al., “Microwave Doppler reflectometer system in LHD”, Rev. Sci. Instrum. Vol. 83(2012) 10E322.
[4] T. Tokuzawa et al.,” Ka-band Microwave Frequency Comb Doppler Reflectometer System for the Large

Helical Device”, Plasma Fusion Res. Vol. 9 (2014) 1402149.
[5] R.Soga et al., “Developments of frequency comb microwave reflectometer for the interchange mode
observations in LHD plasma”, J. Instrument. (JINST) Vol. 11 (2016) C02009.