1. 10 March 2009DVCM Corrections to the energy distribution of the NBI power PPF  Background  History of the problem  Proposed changes  Affected data

2. 10 March 2009DVCM 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 +, D 2 +, D 3 + Source values parameterised in terms of extracted beam current Fitting algorithm used to obtain power fractions in neutral beam for PPF Source flux or density fractions?

3. 10 March 2009DVCM 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 DENSITY so DENSITY fractions given by

4. 10 March 2009DVCM 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 for HC triode PINIs in deuterium only 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) IntensityPower Fraction BES Power Fraction PPF E/11.400E110.7460.841 E/28.506E100.1630.111 E/37.797E100.0910.048

5. 10 March 2009DVCM History 3 - Investigation Thorough review of literature First principles derivation Correct form of equation linking intensity to beam components: FLUX so Doppler spectroscopy gives FLUX fractions from ion source Confirmation that NBTB Doppler shifted BES also computes flux fractions

6. 10 March 2009DVCM Check Intensity Ratios Calculate intensity ratios for different source flux fractions Calculate power ratios for different source flux fractions

7. 10 March 2009DVCM Calculation of Power PPF Total neutral power calculated from measured data Full, half and third fractional flux components from theoretical calculation with 4x10 19 m -2 target

8. 10 March 2009DVCM 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 Power Fraction BES Power Fraction new PPF E/10.7460.74 E/20.1630.14 E/30.0910.12