Solid-state sources, receivers and systems for plasma diagnostics and THz frequency extenders for VNAs

• Main Authors: Hesler, J.L., Duan, Y., Kurtz, D.S., Crowe, T.W.
• Format: Conference Proceeding
• Language: English
• Subjects: Electrical equipment industry; Frequency; Fusion power generation; Industrial control; Microwave generation; Plasma diagnostics; Process control; Schottky barriers; Schottky diodes; Solid state circuits
• ISSN: 0730-9244; 2576-7208
• DOI: 10.1109/PLASMA.2009.5227712

Summary form only given.Higher power and more frequency agile sources and receivers are required for plasma diagnostics, both for fusion research and for industrial process control. VDI generates power in the 100 GHz - 2 THz frequency range through the use of microwave power amplifiers and frequency multipliers based on GaAs Schottky barrier diodes. For example, VDI has demonstrated sources with -450 mW near 100 GHz and several microwatts at 1.9THz. For receivers, VDI has developed both direct diode detectors and heterodyne receivers. The direct detectors operate well across complete waveguide bands and achieve NEP of about lxl 0~Iumleuro WIcirc/Hz at 300GHz and lxl0-10 WIcirc/Hz at 1.5 THz. Heterodyne receivers are achieved with Schottky barrier mixer diodes and their room temperature sensitivity matches the best that has been achieved. These receivers operate across broad frequency bands and VDI is developing full waveguide band systems throughout this frequency range. VDI is also using these components to develop advanced systems. These include a modular extension system for Vector Network Analyzers that will cover the full frequency range for 140 GHz to over 1 THz. This system will use a set of VDI multipliers and mixers in a re configurable fashion to cover each of the waveguide bands in this frequency range. For example, the WR2.2 (330-500GHz) system uses a source consisting of a W-Band amplifier and two doublers. Removing the last doubler yields the WR5.1 (140-220GHz) source. Replacing this doubler with a tripler yields the WR1.5 (500-750GHz) band. A similar modular system is used for the receiver local oscillators. The prototype WR2.2 system has yielded a dynamic range of ~90dB across the entire waveguide band. Similar performance is expected to 1 THz. This talk will focus on the performance and operation of these high frequency components and systems and their potential applications for plasma diagnostics. Particular emphasis will be placed on the VNA extenders, which will be invaluable tools for all manner of laboratory measurements in this frequency range.