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Corrections to the energy distribution of the NBI power PPF

This study delves into the corrections made to the energy distribution of NBI power PPF, tracing the history of the problem, proposed changes, affected data, and detailed calculations. Through a detailed investigation and calculation of power PPF, adjustments to the distribution have been made, impacting different energy fractions. The study sheds light on the evolution of understanding and rectification of previous errors.

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Corrections to the energy distribution of the NBI power PPF

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  1. Corrections to the energy distribution of the NBI power PPF Background History of the problem Proposed changes Affected data DVCM

  2. Background – Beam Species Determination • JET neutral beam is composed of full, half & third energy particles • Intensity of the Doppler shifted Balmer-α lines measured on NBTB • Relative intensities proportional to fractional distribution in source via D-α, neutralisation and dissociation cross sections for D+, D2+, D3+ • Source valuesparameterised in terms of extracted beam current • Fitting algorithm used to obtain power fractions in neutral beam for PPF • Source flux or density fractions? DVCM

  3. History 1 - Hemsworth • pre – 2003 implicit assumption Doppler flux fractions • 2003 JET-DN-C(85)8 (RS Hemsworth) rediscovered i=1,2,3 E, E/2, E/3 b = beam g = gas defines number of radiating transitions per unit length of beam so DENSITY fractions given by DVCM

  4. History 2 – Error Further Compounded “Doppler shifted Balmer alpha spectroscopy on JET neutral beams” G J van Rooij (1994) copies this methodology when describing NBTB system Therefore NB Unit decided that PPF was incorrect because Doppler measurements from NBTB gave density fractions PPF re-written April 2003 for HC triode PINIs in deuterium only • 2008 E Delabie (fz-Jülich) reports inconsistency between PPF and beam emission spectroscopy measurements (both into plasma and into gas) DVCM

  5. History 3 - Investigation • Thorough review of literature • First principles derivation Correct form of equation linking intensity to beam components: so Doppler spectroscopy gives FLUX fractions from ion source • Confirmation that NBTB Doppler shifted BES also computes flux fractions DVCM

  6. Check Intensity Ratios • Calculate power ratios for different source flux fractions • Calculate intensity ratios for different source flux fractions DVCM

  7. Calculation of Power PPF • Total neutral power calculated from measured data • Full, half and third fractional flux components from theoretical calculation with 4x1019m-2 target DVCM

  8. Changes to PPF • Only HC Triode PINIs in D are affected • Total power remains unchanged • Increased power in half and third energy • Decreased power in full energy DVCM

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