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NBI simulations for DEMO1

Perform detailed simulations using NEMO, SPOT, and RISK codes to analyze NBI fast ions in DEMO1 target plasma. Evaluate NBI tangency radius, injection angle, and energy effects on power deposition profiles and current drive efficiency. Understand different deposition profiles by varying simulation parameters. Comparison of SPOT and RISK predictions.

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NBI simulations for DEMO1

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  1. NBI simulations for DEMO1 M Baruzzo1, J F Artaud2, T Bolzonella1 G Giruzzi2, M Schneider2 1) Consorzio RFX 2) CEA Cadarache

  2. Used codes: NEMO+SPOT and NEMO+RISK • Code purpose: • To calculate the NBI fast ions density profiles and several NBI-linked quantities • Code structure: • NEMO calculates the beam path into the plasma taking into account realistic 2D plasma shape, 3D ion source geometry and position and beam divergence. • NEMO calculates analytically the beam absorption and the generated ion density along the beam line taking into account injected species and energy, prescribed plasma density and temperature internal profiles and all of the ionization cross sections. • Some quantities are calculated such as power density deposited on electrons and ions, NBI torque, and beam shine through calculated with the 2D wall geometry. • SPOT generates and evolves the NBI fast ions population with a Monte Carlo approach. NBI quantities such as the driven current and fast ions collisional and first orbit losses. • RISK generates and evolves the NBI fast ions population with a 2D Fokker–Planck calculation.

  3. 2D deposition maps from NEMO: tangency radius scan • Single beam run are performed changing the tangency radius • Einj=1.5 MeV • Pinj=100MW • Rtang=7.7,8,9,10 • Mid-plain injection • SPOT and RISK used for injected ions population evolution

  4. Tangency radius scan with SPOT and RISK Example of single beam runs with 100MW, 1.5MeV NBI and different NBI tangency radii Solid lines are RISK results, dashed lines are SPOT results

  5. Tangency radius scan with SPOT and RISK Solid lines are RISK results, dashed lines are SPOT results

  6. 2D deposition maps from NEMO: injection angle scan 1 2 3 4 5 6 7 8 • Single pini run are performed changing the injection angle • Tangency radius rtang=9m • View from the top is unchanged • Tried 2 different injector position in the (R,Z) plane • For each injector position 4 angles simulated • For each angle two injection energies simulated (1,1.5MeV)

  7. Injection angle and energy scan with SPOT Example of single beam runs with 100MW injected power and different injection angles Solid lines are 1.5MeV energy injection, dashed lines are 1MeV energy injection

  8. Injection angle and energy scan with SPOT Solid lines are 1.5KeV energy injection, dashed lines are 1KeV energy injection

  9. Summary Several simulations have been run on fixed DEMO1 target plasma changing NBI tangency radius, injection angle and injection energy. All of the simulate cases show no shine-through power to the wall. The power deposition profiles predicted by SPOT are peaked slightly more off-axis than RISK, with a larger ratio of electron to ion deposited power. The generated current is also larger in the SPOT case. This might be linked to a larger power deposited off-axis and on electrons, responsible of the ion current screening. The SPOT current drive efficiency is well aligned with PENCIL predictions, and also retains a dependence on tangency radius. Very different deposition profiles can be achieved by changing the injection angles. Very similar profiles can by achieved by the injection from the mid-plain (nbi4) or by the injection from a higher point (nbi5). Almost all the injected angles give good NBI efficiency, (nbi3-nbi5) Lower injection energy implied deposition profiles moved towards the outside and a lower current drive efficiency of about 10%.

  10. NEMO+SPOT • Approximations: • NEMO approximates the beam absorption of ions from all the source points as the absorption from the source center (narrow beam model). • The detail of the source is taken into account to medium level, single beamlets are not described, hyper-beamlets are considered as different sources. • The absorption in SPOT is calculated analytically, only the fast ion propagation is calculated via Montecarlo methods. • RISK approach compared with SPOT is less accurate in modelling NBI transient regimes, and it does not account for magnetic field ripple, fast ion orbit losses and finite orbit width effects. • Integration: • The code can be run in stand-alone mode on prescribed thermal profiles, or it can run integrated in CRONOS or in ITM

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