Ursel Fantz for the IPP-NNBI Team 16 th ICIS, New York City, USAAugust 23-28, 2015 Towards 20 A Negative Hydrogen Ion Beams for Up to 1 hour: Achievements of the ELISE Test Facility Max-Planck-Institut für Plasmaphysik

Ursel Fantz, p. 216 th ICIS: August 23-28, 2015 Neutral Beam Injection (NBI) for ITER Diagnostic beam (100% IN)  3 MW  3 s every 20 s, 100 keV Hydrogen Heating beams (50% EU, 50% JA)  33 MW injected power from 2 injectors  3600 s, 1 MeV Deuterium  15 m beam line based on negative hydrogen ions Residual Ion Dump An international project that aims to demonstrate that fusion is an energy source for the future!

Ursel Fantz, p. 316 th ICIS: August 23-28, 2015 Large and powerful negative ion sources for ITER NBI Requirements  Accelerated current: I = 40 A (Dˉ), I = 46 A (Hˉ)  j D¯ > 200 A/m 2, j H - > 230 A/m 2  j e /j D - < 1 (co-extracted electrons)  Stable for 1 hour  0.2 m 2 extraction area  Uniform (  <10%)  p ≤ 0.3 Pa Cs H, H x + Hˉ Based on the surface process RF-driven negative ion source 1280 apertures in 16 groups 1.9 m 0.9 m 8 RF driver 800 kW RF power at 1 MHz

Ursel Fantz, p. 416 th ICIS: August 23-28, 2015 Large and powerful negative ion sources for ITER NBI 8 driver, 800 kW 1.9 x 0.9 m 2 Extrapolation to large ITER source within the F4E roadmap towards ITER NBI Intermediate step: ELISE Extraction from a Large Ion Source Experiment 1 driver, 100 kW 0.52 x 0.26 m 2 IPP prototype source Heating & Diagnostic beam European NBTF (Italy) 4 driver, 360 kW 1.0 x 0.9 m 2 4 x 2 x ITER reference source since 2007 Neutral Beam Test Facilities

Ursel Fantz, p. 516 th ICIS: August 23-28, 2015 The ELISE test facility Parameter and targets Isotope H -, D - RF power = 2 x 180 kW in 4 drivers A ex = 1000 cm 2, uniformity > 90% I ion,acc = 20 A, I e /I ion < 1 at 0.3 Pa U tot = 60 kV, U ex < 12 kV Plasma: 3600 s, HV: 10 s every s As part of the European roadmap for ITER NBI the project started with a Service Contract with F4E  Construction and assembly finished in Nov 2012  Experimental phase of 2 years  Initial experiments w/o Cs at low RF power  Initial Experiments with Cs (H and D)  Increase of RF power  Optimization in H and D  current campaign

Ursel Fantz, p. 616 th ICIS: August 23-28, 2015 ELISE test facility – Short pulse operation Size scaling: ELISE source performance compared to prototype source at BATMAN  Similar dependencies  Lower Cs consumption than expected 20 s plasma, 10 s beam  Less magnetic filter field needed  80 kW/driver should be sufficient

Ursel Fantz, p. 716 th ICIS: August 23-28, 2015 ELISE test facility – Towards long pulses Stable ion currents (within 5%) but high dynamics of co-extracted electrons Co-extracted electrons limit source performance, in particular in deuterium ! j e /j ion < 1j e /j ion > 1 Cs release by back-streaming ions

Ursel Fantz, p. 816 th ICIS: August 23-28, 2015 ELISE test facility – Long pulse operation Jan/Feb 2015: Focus on long pulses with medium RF power at 0.3 Pa in hydrogen some statistics Best 400 s pulse up to now I ion = 18.3 A, j e /j ion < 0.73 (45 kW/driver) Unpredictable trend for co-extracted electrons  Influence of Cs dynamics !  Role of back-streaming ions ?  Ions OK, but parameters limited by electrons

Ursel Fantz, p. 916 th ICIS: August 23-28, 2015 Long pulse operation at MANITU equipped with the prototype source Prototype source 0.52 m ~ 100 A/m 2 Extension of pulse length Time traces: Dependence on RF powerPulsed and continuous extraction

Ursel Fantz, p th ICIS: August 23-28, 2015 ELISE test facility – Long pulse operation Record-setting one hour pulse at 0.3 Pa in hydrogen Best 3600 s pulse up to now  ion = 9.3 A, j e /j ion < 0.4 (20 kW/driver)  Cs oven switched off  Significant conditioning between 1 st and 2 nd beam blip; slow de-conditioning afterwards H¯ beam on the calorimeter First pulse (20 s, 0.6 Pa)

Ursel Fantz, p th ICIS: August 23-28, 2015 ELISE test facility – Beam diagnostics Advanced beam calorimetry To determine beam divergence and beam homogeneity  Diagnostic calorimeter with thermocouples, water calorimetry and IR data analysis  Beam Emission Spectroscopy (BES with 20 LoS)  Tungsten wire calorimeter Grid system

Ursel Fantz, p th ICIS: August 23-28, 2015 ELISE test facility – Beam diagnostics HH Doppler-shifted Grid system BES & BBCNI BES standard analysis Advanced beam calorimetry To determine beam divergence and beam homogeneity  Diagnostic calorimeter with thermocouples, water calorimetry and IR data analysis  Beam Emission Spectroscopy (BES with 20 LoS)  Tungsten wire calorimeter In perveance optimum: divergence between 1° and 2°

Ursel Fantz, p th ICIS: August 23-28, 2015 ELISE test facility – Beam diagnostics In perveance optimum: divergence between 1° and 2° and homogeneity better than 90 %  upper segment  lower segment Beamlet group Advanced beam calorimetry To determine beam divergence and beam homogeneity  Diagnostic calorimeter with thermocouples, water calorimetry and IR data analysis  Beam Emission Spectroscopy (BES with 20 LoS)  Tungsten wire calorimeter

Ursel Fantz, p th ICIS: August 23-28, 2015 ELISE test facility – Opening after 2 years of operation Inspection of source vessel  Faraday screens OK  Moderate Cs contamination  Coating of diagnostic windows  Traces of back-streaming ions Diagnostic windows Cs coating Driver with Faraday screen Grid pattern b.s. ions Driver with Faraday screen Grid pattern b.s. ions

Ursel Fantz, p th ICIS: August 23-28, 2015 ELISE test facility – Opening after 2 years of operation BP PG EG GG Bias Plate Plasma Grounded Grid Extraction Extraction system  No damages (melting)  Minor displacements  Some Cs  Cu sputtering ?  Black rings on EG ? EG PG upper half PG back side EG

Ursel Fantz, p th ICIS: August 23-28, 2015 ELISE test facility – The next steps Main task: Control of co-extracted electrons (and Cs) esp. for long pulses and for deuterium Towards ITER parameters  Increase RF power to achieve required ion current densities  Develop strategies to suppress co-extracted electrons  Stability in long pulses  Beam homogeneity Poster W. Kraus Thursday ThurPE11 Restart in deuterium with clean source Talk on boundary layer by C. Wimmer Thursday, ThurA02

Ursel Fantz, p th ICIS: August 23-28, 2015 Towards 20 A Negative Hydrogen Ion Beams for Up to 1 hour Achievements of the ELISE Test Facility Experience in operation of large RF beam sources  2 years of successful operation  Inspection and maintenance  Similar dependencies as in prototype source  Less Cs consumption as expected  Lower magnetic filter field needed  80 kW/ driver should be sufficient  Beam homogeneity better than 90% SPIDER, 2014+ELISE, 2012+MITICA, NBTF in Padua, Italy Important step within the European roadmap for ITER NBI ITER NBI I ion PulsePower/driver 25.5 A 20 s52 kW 18.3 A400 s45 kW 9.3 A1 h20 kW Hydrogen, 0.3 Pa, e/ion < 1 Co-extracted electrons limit source performance, in particular in deuterium !