System-on-chip approach microwave imaging reflectometer on DIII-D tokamak

Area of Science:

• Plasma Physics
• Fusion Energy Research
• Microwave Engineering

Background:

• The DIII-D tokamak requires advanced diagnostics for studying plasma behavior.
• Previous millimeter-wave imaging reflectometer (MIR) systems faced limitations in power delivery and spatial constraints.

Purpose of the Study:

• To upgrade the two-dimensional MIR system for enhanced density fluctuation imaging on the DIII-D tokamak.
• To implement a V-band system utilizing customized CMOS integrated circuits for improved performance.

Main Methods:

• Development of customized CMOS chips for transmitter and receiver modules operating in the 55-75 GHz band.
• Integration of an active frequency multiplier chain, replacing quasi-optical local oscillator coupling.
• Incorporation of a 55-75 GHz low noise amplifier in the receiver module.

Main Results:

• Successful development and implementation of a V-band MIR system on the DIII-D tokamak.
• Achieved a 20 dB gain improvement and better than -75 dBm sensitivity in receiver modules.
• Reduced electronics noise temperature from 55,000 K to 11,200 K.

Conclusions:

• The upgraded V-band MIR system, leveraging system-on-chip technology, significantly enhances density fluctuation imaging capabilities.
• The new system facilitates co-located multi-field investigation of MHD-scale fluctuations in the pedestal region.
• This advancement supports detailed analysis of fusion plasma dynamics.