Slide 1 The Heavy Ion Fusion Science Virtual National Laboratory Algorithm and Model Verification and Validation For Kinetic Plasma Simulation Codes

Slide 2 The Heavy Ion Fusion Science Virtual National Laboratory Overview Main goal of the workshop is to start development of test problems for verification and validation of plasma physics codes This was the first of a series of workshops – the goal of the first was to gather and align the community to identify and agree upon benchmark problems (Eric Sonnendrucker volunteered to host the next one) The test problems must be very precisely defined to avoid ambiguity of results – i.e. differences in results are due to algorithmic difference and not due to differences in test cases Verification – ensuring that the methods are properly implemented Validation – ensuring that the code is producing the correct physics (agrees with experiment) Code to code comparisons are interesting and useful, but do not provide validation

Slide 3 The Heavy Ion Fusion Science Virtual National Laboratory Levels of difficulty Easy problems – agreed upon solution, preferably analytic. One possibility is manufactured solutions. Medium problems – agreed upon solution, but only obtainable numerically – e.g. from a high resolution simulation. Hard problems – solution is not fully known, only expect agreement to within some specified percent. Can rely on experimental results for the “exact” solution.

Slide 4 The Heavy Ion Fusion Science Virtual National Laboratory Format The workshop was a series of presentations, each speaker providing possible test cases –40 minutes for initial presentation –20 minute break, allowing time for thought and side discussions –20 minutes for follow up questions and discussions Test panel – several volunteers had run several preselected test cases before the workshop and presented results At the last day, three break out groups developed a short list of test case candidates in different areas

Slide 5 The Heavy Ion Fusion Science Virtual National Laboratory Program Monday, November 12, :30AM - 10:10AM Turner et. al. - Benchmarks for particle-in-cell simulations with Monte Carlo collisions 10:40AM - 11:20AM Giuliano et. al. - Particle simulation of dynamics for ion beam injection into a rarefied gas 1:30PM - 2:10PM Larson - Test problems for Coulomb collison algorithms (cancelled) 2:40PM - 3:20PM Cartwright - Towards an Emission Verification Test Suite 3:50PM - 4:30PM Hitchon - Physical Tests of Kinetic Simulations Tuesday, November 13, :30AM - 10:10AM Grote et. al. - Verification and Validation for Simulations of Intense Particle Beams and Non-Neutral Ions. 10:40AM - 11:20AM Smithe - Verification and Validation Problems Relating to Vacuum Electronics 1:30PM - 2:10PM Greenwood - Faraday Rotation Proposed Test Problem Algorithm and Model Verifcation and Validation for Kinetic Plasma Simulation Codes 2:40PM - 3:20PM Filbet - Inverse Lax-wendroff Method For Kinetic Models In Complex Geometry 3:50PM - 4:30PM Mehrenberger - BB BOT: Berk Breizman and Bump on Tail Test Cases Wednesday, November 14, :30AM - 10:10AM Banks et. al. - Tests for Collisionless Electrostatic Codes 10:40AM - 11:20AM Hara et. al. - Collisionless Sheath Problem for Testing Vlasov Solvers 1:30PM - 2:10PM Swanekamp et. al. - Non-Neutral Magnetic Vortex Dynamics 2:40PM - 3:20PM Sonnedrucker et. al. - 2D Electrostatic Simulations of KEEN Waves 4:30PM - 5:30PM Test Panel Discussion - Cartwright, Chang, Greenwood, Smithe, Chacon Thursday, November 15, :30AM - 12:00PM Breakout Groups and Planning for Second Workshop

Slide 6 The Heavy Ion Fusion Science Virtual National Laboratory Test panel Two test cases were preselected and tried by several volunteers –ES diode with virtual cathode –Cylindrical plasma between two conductors, to examine sheath formation The results made it clear how precisely the problem must be defined –In both cases, each volunteer saw very different results because of different assumptions –In some cases, thousands of hours of CPU time were used for the test cases

Slide 7 The Heavy Ion Fusion Science Virtual National Laboratory Break out sessions Three groups for three areas –ES beams o Diode o Long distance beam propagation –EM plasmas o Drifting plasma o Magnetic switch –ES plasmas with collisions o Plasma processing related

Slide 8 The Heavy Ion Fusion Science Virtual National Laboratory ES beams Diode –1-D –2-D infinite –2-D finite –Low temperature T/V << 1 (no sheath) –High temperature T/V ~ ¼ –Stable and unstable virtual cathode Beam with uniform focusing (or plasma) –Matched and mismatched –1-D axisymmetric –2-D slab, cylinder Ground V diode