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Register a new userElectric Fields in a Tokamak
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Added by
Robert W. Johnson Jr
Publication date
2011
fields
Physics
and research's language is
English
Authors
Robert W. Johnson
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With the establishment of vanishing net electrostatic fields in a toroidally symmetric tokamak at equilibrium [R. W. Johnson, to appear in Phys. Rev. D], one is left needing an explanation for the measurement of an apparent radial electric field in experiments. Two scenarios are proposed, depending on the type of measurement being considered. Indirect measurement via the radial equation of motion for an impurity species possibly measures that species net radial viscous force, and direct measurement via the motional Stark effect might reveal electric fields generated by the shifting of the toroidal magnetic flux density.
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A novel proton imaging technique was applied which allows a continuous temporal record of electric fields within a time window of several nanoseconds. This proton streak deflectometry was used to investigate transient electric fields of intense (~ 10^17 W/cm^2) laser irradiated foils. We found out that these fields with an absolute peak of up to 10^8 V/m extend over millimeter lateral extension and decay at nanosecond duration. Hence, they last much longer than the (~ ps) laser excitation, and extend much beyond the laser irradiation focus.
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