skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Radio-frequency power-assisted performance improvement of a magnetohydrodynamic power generator

Abstract

We describe a radio-frequency (rf) electromagnetic-field-assisted magnetohydrodynamic power generation experiment, where an inductively coupled rf field (13.56 MHz, 5.2 kW) is continuously supplied to the disk generator. The rf power assists the precise plasma ignition, by which the otherwise irregular plasma behavior was stabilized. The rf heating suppresses the ionization instability in the plasma behavior and homogenizes the nonuniformity of the plasma structures. The power-generating performance is significantly improved with the aid of the rf power under wide seeding conditions: insufficient, optimum, and excessive seed fractions. The increment of the enthalpy extraction ratio of around 2% is significantly greater than the fraction of the net rf power, that is, 0.16%, to the thermal input.

Authors:
; ;  [1]
  1. Department of Energy Sciences, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8502 (Japan)
Publication Date:
OSTI Identifier:
20714143
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 98; Journal Issue: 11; Other Information: DOI: 10.1063/1.2138803; (c) 2005 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ELECTROMAGNETIC FIELDS; ENTHALPY; IONIZATION; MAGNETOHYDRODYNAMICS; MHZ RANGE 01-100; PLASMA; PLASMA HEATING; PLASMA INSTABILITY; PLASMA PRODUCTION; POWER GENERATION; RADIOWAVE RADIATION; RF SYSTEMS; THERMODYNAMICS; THERMONUCLEAR IGNITION

Citation Formats

Murakami, Tomoyuki, Okuno, Yoshihiro, and Yamasaki, Hiroyuki. Radio-frequency power-assisted performance improvement of a magnetohydrodynamic power generator. United States: N. p., 2005. Web. doi:10.1063/1.2138803.
Murakami, Tomoyuki, Okuno, Yoshihiro, & Yamasaki, Hiroyuki. Radio-frequency power-assisted performance improvement of a magnetohydrodynamic power generator. United States. doi:10.1063/1.2138803.
Murakami, Tomoyuki, Okuno, Yoshihiro, and Yamasaki, Hiroyuki. Thu . "Radio-frequency power-assisted performance improvement of a magnetohydrodynamic power generator". United States. doi:10.1063/1.2138803.
@article{osti_20714143,
title = {Radio-frequency power-assisted performance improvement of a magnetohydrodynamic power generator},
author = {Murakami, Tomoyuki and Okuno, Yoshihiro and Yamasaki, Hiroyuki},
abstractNote = {We describe a radio-frequency (rf) electromagnetic-field-assisted magnetohydrodynamic power generation experiment, where an inductively coupled rf field (13.56 MHz, 5.2 kW) is continuously supplied to the disk generator. The rf power assists the precise plasma ignition, by which the otherwise irregular plasma behavior was stabilized. The rf heating suppresses the ionization instability in the plasma behavior and homogenizes the nonuniformity of the plasma structures. The power-generating performance is significantly improved with the aid of the rf power under wide seeding conditions: insufficient, optimum, and excessive seed fractions. The increment of the enthalpy extraction ratio of around 2% is significantly greater than the fraction of the net rf power, that is, 0.16%, to the thermal input.},
doi = {10.1063/1.2138803},
journal = {Journal of Applied Physics},
number = 11,
volume = 98,
place = {United States},
year = {Thu Dec 01 00:00:00 EST 2005},
month = {Thu Dec 01 00:00:00 EST 2005}
}
  • We describe the effect of a radio-frequency (rf) power application on the performance of a magnetohydrodynamic (MHD) electrical power generator, as determined through shock-tunnel-based experiments and quasi-three-dimensional numerical simulations. The temporal plasma-fluid behavior, the one-dimensional plasma-fluid structure, the enthalpy-entropy diagram, the quality of the energy conversion efficiency, and the energy flow in the power-generating system are investigated. Preionization assistance by a small amount of rf power drastically changes the entire MHD power-generating system; the MHD extraction length is considerably extended and the isentropic efficiency is significantly improved.
  • By applying a radio-frequency (RF) electromagnetic field, the feasibility of improvement in the performance of a nonequilibrium disk-shaped magnetohydrodynamic (MHD) generator suffering from water vapor contamination in the working gas is investigated with r-[theta] two-dimensional numerical simulations. Attention is paid to the relation between the behavior of MHD plasma in the presence of the RF electric field and the generator performance. The water contamination causes the strongly nonuniform and unsteady plasma, and deteriorates its performance. The fluctuations of the electron temperature and of the ionization degree of seed atoms are found to be suppressed by applying the RF electric field.more » As a result, the enthalpy extraction ratio and the isentropic efficiency of the generator improve. The ratio of the required additional joule heating by the RF electric field to the thermal input to the generator for the stabilization of the plasma and the improvement in the performance is estimated to be about 0.9%.« less
  • The present paper describes the performance of a radio-frequency (rf) electromagnetic-field-assisted magnetohydrodynamics (MHD) electrical power generator and compares it to a multiple-load MHD generator. rf heating which is superimposed on self-excited Joule heating preionizes cesium-seeded helium gas independent of the in situ loading conditions, whereby Hall potential profile is improved and electron temperature is increased. Furthermore, the dynamic stabilization effect cancels ionization instability and homogenizes plasma structure, which is the most important superiority of the rf-power assistance over a conventional plasma actuation by loading-rate control. The power-generating performance is significantly improved with the aid of the rf power under widemore » seeding and loading conditions, where the electrical load-matching characteristic is slightly changed.« less
  • We report a simple, efficient, high voltage radio frequency (RF) generator powered by a single voltage source (1.5-7 V) to resonantly drive ion traps or other capacitive loads. Our circuit is able to deliver RF voltages > 500 V{sub p-p} at frequencies ranging from 0.1 to 10 MHz. This RF oscillator uses low-cost, commercially available components, and can be easily assembled onto a circuit board of a few cm{sup 2}. Because of its simplicity and good efficiency, this circuit is useful in applications requiring small size and low power consumption such as portable ion trap systems where the duration ofmore » operation under battery power is of concern.« less