Development and testing of a fast fourier transform high dynamic-range spectral diagnostics for millimeter wave characterization

A fast Fourier transform (FFT) based wide range millimeter wave diagnostics for spectral characterization of scattered millimeter waves in plasmas has been successfully brought into operation. The scattered millimeter waves are heterodyne downconverted and directly digitized using a fast analog-digital converter and a compact peripheral component interconnect computer. Frequency spectra are obtained by FFT in the time domain of the intermediate frequency signal. The scattered millimeter waves are generated during high power electron cyclotron resonance heating experiments on the TEXTOR tokamak and demonstrate the performance of the diagnostics and, in particular, the usability of direct digitizing and Fourier transformation of millimeter wave signals. The diagnostics is able to acquire 4 GHz wide spectra of signals in the range of 136-140 GHz. The rate of spectra is tunable and has been tested between 200 000 spectra/s with a frequency resolution of 100 MHz and 120 spectra/s with a frequency resolution of 25 kHz. The respective dynamic ranges are 52 and 88 dB. Major benefits of the new diagnostics are a tunable time and frequency resolution due to postdetection, near-real time processing of the acquired data. This diagnostics has a wider application in astrophysics, earth observation, plasma physics, and molecular spectroscopy for the detection and analysis of millimeter wave radiation, providing high-resolution spectra at high temporal resolution and large dynamic range

A line-of-sight electron cyclotron emission receiver for electron cyclotron resonance heating feedback control of tearing modes

An electron cyclotron emission (ECE) receiver inside the electron cyclotron resonance heating (ECRH) transmission line has been brought into operation. The ECE is extracted by placing a quartz plate acting as a Fabry¿Perot interferometer under an angle inside the electron cyclotron wave (ECW) beam. ECE measurements are obtained during high power ECRH operation. Thisdemonstrates the successful operation of the diagnostic and, in particular, a sufficient suppression of the gyrotron component preventing it from interfering with ECE measurements. When integratedinto a feedback system for the control of plasma instabilities this line-of-sight ECE diagnosticremoves the need to localize the instabilities in absolute coordinates

Production of solar fuels by CO2 plasmolysis

A storage scheme for Renewable Energy (RE) based on the plasmolysis of CO2into CO and O2 has been experimentally investigated, demonstrating high energy efficiency (>50%) combined with high energy density, rapid start-stop and no use of scarce materials. The key parameter controlling energy efficiency has been identified as the reduced electric field. Basic plasma parameters including density and temperature are derived from a simple particle and energy balance model, allowing parameter specification of an upscale 100 kW reactor. With RE powered plasmolysis as the critical element, a CO2 neutral energy system becomes feasible when complemented by effective capture of CO2 at the input and separation of CO from the output gas stream followed by downstream chemical processing into hydrocarbon fuels

Fast fourier transform based diagnostics for spectral characterization of millimeter waves in tokamaks

A Fast Fourier Transform (FFT) based wide range millimeter wave diagnostics for spectral characterization of scattered millimeter waves in plasmas has been successfully brought into operation. The scattered millimeter waves are heterodyne down-converted and directly digitized using a fast analog-digital converter (ADC) and a compact Peripheral Component Interconnect (cPCI) computer. Frequency spectra are obtained by FFT in the time domain of the intermediate frequency signal. The scattered millimeter waves are generated during high power Electron Cyclotron Resonance Heating (ECRH) experiments on the TEXTOR Tokamak and demonstrate the performance of the diagnostics and, in particular, the usability of direct digitizing and Fourier transformation of millimeter wave signals. Major benefit of the new diagnostics is a tunable time and frequency resolution due to post-detection, near-Real-Time processing of the acquired data. This diagnostics has a wider application in astrophysics, earth observation, plasma physics and molecular spectroscopy for the detection and analysis of millimeter wave radiation, providing high-resolution spectra at high temporal resolution and large dynamic range. Such a diagnostics also has the potential to detect Electron Cyclotron Emission (ECE) and to be used in Real-Time ECE feedback control systems. © 2009 IEEE

Multidimensional fear of failure measurement : the performance failure appraisal inventory

The strong non-equilibrium conditions provided by the plasma phase offer the opportunity to beat traditional thermal process energy efficiencies via preferential excitation of molecular vibrations. Simple molecular physics considerations are presented to explain potential dissociation pathways in plasma and their effect on energy efficiency. A common microwave reactor approach is evaluated experimentally with Rayleigh scattering and Fourier transform infrared spectroscopy to assess gas temperatures (exceeding 104 K) and conversion degrees (up to 30%), respectively. The results are interpreted on a basis of estimates of the plasma dynamics obtained with electron energy distribution functions calculated with a Boltzmann solver. It indicates that the intrinsic electron energies are higher than is favorable for preferential vibrational excitation due to dissociative excitation, which causes thermodynamic equilibrium chemistry to dominate. The highest observed energy efficiencies of 45% indicate that non-equilibrium dynamics had been at play. A novel approach involving additives of low ionization potential to tailor the electron energies to the vibrational excitation regime is propose