# Presentation: 708073

## Generic questions

**New scientific insights/conceptual breakthroughs enabled  by SciDAC**
**Changed understanding of mode ICRF conversion**
**Importance of conversion to ion cyclotron wave**
**Solution in 2D – gives never before seen complete picture, connects antenna to conversion region**
**Textbook example of partnership of theory, experiment, computational modeling**
**Potential breakthroughs**
**Full wave lower hybrid solutions – role of diffraction and spectral broadening**
**Solutions in 3D – mode conversion, interaction with 3D plasma perturbation, MHD processes**
**Arbitrary non-Maxwellian distribution in non-uniform distributions – higher dimensions**
**Demonstrated utilization of terascale computing**
**Next slide**
**Likelyhood of timely delivery of timely delivery of terascale computing capability modeling capabilities addressing burning plasma physics issues relevant to ITER**
**Certain**
**We already can do fast wave calculations for relevant ITER parameters, including non-thermal effects**
**We have codes capable of studying mode conversion and full wave lower hybrid on ITER (if we could get a big enough computer) – INSITE proposal being developed**
**Our models are ready to be integrated with transport models and MHD and will be necessary elements for ITER scenario design and experimental interpretation**

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## Demonstrated utilization of terascale computing capability

**AORSA jobs run last two weeks**

**And there is effective usage of terascale computers**

|  | Fourier space | Configuration space |
| --- | --- | --- |
| Number of equations | 248,832 | 39,492 |
| Matrix size | 990 Gbytes | 25 GBytes |
| Time to load matrix | 1.2 min | 7.1 min |
| Matrix solve (ScaLAPACK | 344 min | 3.5 min |
| Fourier transform | 9.5 min | 0.04 min |
| Total CPU time | 358 min | 13.4 min |
| Flops/processor | 1.1 Gflops | 0.25 Gflops |

**There is usage of terascale computers**

**AORSA is a JOULE code**

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## Generic questions

**Specific steps to ensure more analysis of simulation data**
**Relation of solutions to simple 0D/1D wave concepts**
**Local modes**
**Mode conversion**
**Local damping or macroscopic force**
**New fundamental concepts of wave plasma interaction**
**        ****Fair question we will have to think about how to do this better****   **
**Code verification – multiple code instance – AORSA/TORIC, CQL3D, Orbit/RF, direct orbit integration in Rf fields**
**Code validation – we have an ongoing program of comparison with experiments**
**What would our ideal computer look like?**
**We have many different mathematical operations so we need a well balanced platform**
**We can’t say whether vector vs MPP scalar is better, yet – not enough experience with new vector architecture and we don’t know where the bottlenecks will be with integrated codes**
**There is an upper limit on memory/speed/run time required for ITER, but we can only give gross extrapolations as to what these are.**
**Reasonable turn around time**

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## Specific questions

**What will we do to validate the quasilinear approach?**
**Issue 1 – decorrelation of particle orbits in RF field solutions**
**Plug in numbers in Stix Chapter 14-17**
**To explore other decorrelation mechanisms – direct orbit solutions and comparison**
**Issue 2 – linearization of Vlasov-Maxwell system that give the first order equations ******** nonlinear mode coupling **
**Probably ok in core plasma, likely not ok in edge plasma where nonlinear effects  may be present**
**Part of our edge/antenna component addresses this – Time dependent PIC simulation**
**Also a fair question that we will put some thought into**
**Does bounce average include radial motion of fast particles?**
**No – CQL3D is a zero orbit width code (i.e. particles stay on a flux surface).  Both the collision operator and the quasilinear operator are bounce averaged with this assumption.  AORSA calculates velocity space diffusion coefficients local in space and velocity space which are then bounce averaged assuming no deviation from flux surface**
**Plans for terascale computing applications beyond linear dense matrix solve?**
**Dense matrix solve in no longer the dominant computation load in AORSA**
**High resolution mode conversion calculations, full wave lower hybrid**
**Integrated models – AORSA/Fokker Planck, TORIC/TOPICA, Edge/antenna integrated models**

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