ProVac3D a TPMC program for complex vacuum systems

Transcription

1 ProVac3D a TPMC program for complex acuum systems X. Luo, S. Varoutis, H. Haas, S. Hanke and C. Day INSTITUTE FOR TECHNICAL PHYSICS - VACUUM DEPARTMENT TIMO Peter Ginter KIT Uniersity of the State of Baden-Wuerttemberg and National Laboratory of the Helmholtz Association

2 Talk Outline 1. Introduction of ProVac3D 2. Recent deelopment A. Parallelization B. Transition flow C. Radiation heat load 3. Application example 4. Conclusions May, th IUVSTA Workshop on Vacuum Gas Dynamics, Leinsweiler, Germany

3 1. Introduction of ProVac3D -3D density Profile of the Vacuum system Test Particle Monte Carlo simulation Geometry definition Plane component Parallelogram Triangle Circle Ellipse Ring Hexagon with hole Square with hole Octagon with hole Rotational component Cylinder Cone Crown half sphere Elliptic cylinder Wedge 3-way cross 4-way cross 5-way cross 6-way cross May, th IUVSTA Workshop on Vacuum Gas Dynamics, Leinsweiler, Germany

4 Calculation of the density distribution 1. The whole acuum system or the olumes of interest are diided into cells. V(i 2. The mean time of flight of eery molecule in the cells is recorded. fts(i 3. The density in one cell is n(i=cfts(i/v(i May, th IUVSTA Workshop on Vacuum Gas Dynamics, Leinsweiler, Germany

5 2. Recent deelopment A. Parallelization HPC-FF at Jülich Supercomputing Centre (JSC: High Performance Computing For Fusion dedicated to European Fusion Research Community 1080 compute nodes, 8640 cores in total 2xIntel Xeon X5570 (Nehalem-EP Quad-core GHz 24 GB local memory (DDR3, 1066 MHz max. wallclocktime 24 h max. number of nodes 512 max. no. of running obs 15 HC3 (HP XC3000 at Steinbuch Centre for Computing (SCC of KIT 332 compute nodes, 2656 cores in total 2x Intel Xeon Quad-core GHz 24 GB or 48 GB local memory max. wallclocktime 72 h max. number of nodes 256 max. no. of running obs May, th IUVSTA Workshop on Vacuum Gas Dynamics, Leinsweiler, Germany

6 Speed-up by parallelization Simulation model May, th IUVSTA Workshop on Vacuum Gas Dynamics, Leinsweiler, Germany

7 B. Implement of the molecular collisions by the interaction between the probe molecule and the target molecule in the background target molecule wall probe molecule i background gas molecules P(x the probability that the probe molecule meets target molecule of the background before it has passed a distance x P( x 1exp( n( x dx Collision cross section May, th IUVSTA Workshop on Vacuum Gas Dynamics, Leinsweiler, Germany

8 Determination of the collision time x( t 0 n( x( probe u bulk dt log( rnd random number within (0,1 Suppose is the possible collision time with the wall, collision with the target molecule happens when t <, at the position: x x 0 probe t On the other hand, collision with the wall happens when t > May, th IUVSTA Workshop on Vacuum Gas Dynamics, Leinsweiler, Germany

9 May, th IUVSTA Workshop on Vacuum Gas Dynamics, Leinsweiler, Germany - Hard sphere collision model Velocity of the target molecule z y x u z u y u x cos( ( sin( sin( ( cos( sin( ( x y z Velocity of the probe molecule after the collision 2 2 1, ( cos( ( sin( sin( ( cos( sin( ( ( i relatie i i i i i i relatie i with z e y e x e e The elocity after the molecular collision (t<

10 Comparison with the experiment 15C L= m D= m L/D=9.75 Initial n 0 =10 18, corresponding to P1= Pa and Kn= n=10 17 and total iteration step k=9990 Final n=10 21, corresponding to P1=3.98 Pa and Kn=0.1 computation time 112 hours by a desktop PC with a 2.67 GHz May, th IUVSTA Workshop on Vacuum Gas Dynamics, Leinsweiler, Germany

11 C. Simulation of the radiation heat load The iew factor method F 12 cos1 cos2 2 S da 2 When the components are shaded or partially shaded by each other, the calculation is getting more difficult. The subroutines to calculate the radiation heat load in ProVac3D is under deelopment. The adantage is that the calculations use the same geometry model as the acuum simulations May, th IUVSTA Workshop on Vacuum Gas Dynamics, Leinsweiler, Germany

12 3. Application example 5 ports for 3 x x 1 = 8 high performance and large-scale customized cryopumps No any commercial pump can meet the requirements of the ITER May, th IUVSTA Workshop on Vacuum Gas Dynamics, Leinsweiler, Germany

13 A. ITER Model Pump and the Test facility Features of the model pump (1 Reduced scale: D=1.2 m, L=1.36 m (2 External cryogenic supply (3 Integrated ale (416 charcoal coated panels (L=0.87 m, W=0.145 m at 4.5K 28 cryogenic panels for ITER cryopump Sticking coefficient Deuterium (D 2 Protium (H 2 Helium (He taken from experiment May, th IUVSTA Workshop on Vacuum Gas Dynamics, Leinsweiler, Germany

14 Cryogenic components of the model pump 80 K radiation shield enelope 16 cryosorption panels 80 K radiation shield and louer baffles The cryogenic panels break the reolution symmetry of the pump May, th IUVSTA Workshop on Vacuum Gas Dynamics, Leinsweiler, Germany

15 Test facility for the ITER Model Pump (TIMO TIMO Vessel PNEUROP Dome Model Pump May, th IUVSTA Workshop on Vacuum Gas Dynamics, Leinsweiler, Germany

16 Simulation model by ProVac3D True 3D model composed of 73 components Vale Gas source tube P1 and P2: two positions to measure the pressures The components in red: 80 K radiation shields The components in blue: 4.5 K cyrosorption panels The components in black: pump wall, ale head and the TIMO essel The components in green: irtual surfaces to do statistics The macroscopic parameters are calculated for the regions enclosed by pink May, th IUVSTA Workshop on Vacuum Gas Dynamics, Leinsweiler, Germany

17 Pumping speed The agreement is good except for small ale openings. The upper applicable limit is 1000 sccm, corresponding to a gas flux 4.5 Pa m 3 /s/m May, th IUVSTA Workshop on Vacuum Gas Dynamics, Leinsweiler, Germany

18 Virtual capture factors C1, C2 and C3 C3 associated with the cryosorption panels is important May, th IUVSTA Workshop on Vacuum Gas Dynamics, Leinsweiler, Germany

19 4. Conclusions ProVac3D is a ersatile Monte Carlo simulation tool It is ery suitable to simulate a complex acuum system characterized by distributed gas loads and pumps, high temperature gradients, and different thermal accommodation coefficients. It has been parallelized. The molecular collision is included by the interaction of the probe particle with the target particle in the background. The subroutines for radiation heat load are under deelopment May, th IUVSTA Workshop on Vacuum Gas Dynamics, Leinsweiler, Germany