PPPL-3958 is available in <a href="PPPL-3958.pdf">pdf</a> format (1.1 MB).

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<b>Measurement of the Internal Magnetic Field of Plasmas using an Alpha Particle Source</b>
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<b>Authors:</b> S.J. Zweben, D.S. Darrow, P.W. Ross, J.L. Lowrance, and G. Renda
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<b>Date of PPPL Report:</b> May 2004
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<b>Presented at:</b> the 15th Topical Conference on High-temperature Plasma Diagnostics, 19-22 April, 2004, San Diego, CA; proceedings to be published in the Review of Scientific Instruments.
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The internal magnetic fields of plasmas can be measured under certain conditions from the integrated v x B deflection of MeV alpha particles emitted by a small radioactive  source. This alpha source and large-area alpha-particle detector would be located inside the vacuum vessel but outside the plasma. Alphas with a typical energy of 5.5 MeV (<sup>241</sup>Am) can reach the center of almost all laboratory plasmas and magnetic fusion devices, so this method can potentially determine the q(r) profile of tokamaks or STs. Orbit calculations, background evaluations, and conceptual designs for such a v x B (or "AVB") detector are described.




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