Temperature Simulation DCCT at PETRA III D Lipka
- Slides: 21
Temperature Simulation DCCT at PETRA III D. Lipka, MDI, DESY Hamburg; 27. 08. 2010
Problem • • • Two cases of operation with different temperatures at the current monitor observed Case 1: I 1=85 m. A, N=160 Bunches gives about 70°C Case 2: I 2=65 m. A, N=40 Bunches gives about 130°C Questions: Why case 2 higher temperature? Why temperature high? D. Lipka, MDI, DESY Hamburg; 27. 08. 2010
Answer Problem 1 • • • Power P = I Q kloss I is mean beam current Q is charge = I Dt Dt is bunch distance = t / N t is PETRA III revolution time = 7. 685 µs kloss is voltage loss per charge for a structure Result in P = I 2 t kloss / N P 1/P 2 = 0. 43 Because P 2 is higher the temperature is higher! Compare: PE-XFEL, max/P 2=0. 0001 D. Lipka, MDI, DESY Hamburg; 27. 08. 2010
Setup DCCT PEEK Al. Mg 3 µ-metal Stainless Steel Cu. Be Iron ceramic In CST imported model from Annette Brenger D. Lipka, MDI, DESY Hamburg; 27. 08. 2010
Inner Setup Bellow shielded, but results in a resonator Ceramic coated with Molybdenum. When a charged particle moves through DCCT, it looses energy due to gap=8. 2 mm! D. Lipka, MDI, DESY Hamburg; 27. 08. 2010
Simulation 1. Wakefield simulation with beam: get energy loss 2. Eigenmode of setup: get field distribution of loss 3. Thermal: input power and field distribution, get temperature distribution D. Lipka, MDI, DESY Hamburg; 27. 08. 2010
Wakefield Simulation Mesh cells around bellow and ceramic: Simulation tool can not resolve bellow and coating perfect! Anyhow: kloss=39. 1 V/n. C ->P 1=13. 6 W, P 2=31. 7 W D. Lipka, MDI, DESY Hamburg; 27. 08. 2010
Eigenmode Simulation Setup: only vacuum part Field distribution between bellow and shielding D. Lipka, MDI, DESY Hamburg; 27. 08. 2010
Temperature Distribution P 2 Included: heat conductivity of all materials and heat radiation No special cooling available, next is 4. 2 m away. Therefore cooling applied at the end of both beam pipes at 2. 1 m No cooling in x and y Here maximum temperature of 107 °C D. Lipka, MDI, DESY Hamburg; 27. 08. 2010
Temperature distribution shortened P 2 Here the distance to cooling is only 200 mm, Tmax=106°C, because heat radiation along pipe acts like a cooling, therefore this shortened model can be used Measured 130°C; Simulation underestimates temperature by 18%, reason: mesh, perhaps higher loss factor in reality D. Lipka, MDI, DESY Hamburg; 27. 08. 2010
Temperature distribution P 2 with airflow Here the simulation box increased with cooling at xmin, max and ymin, max, Tmax reduces from 106°C to 87. 5 °C D. Lipka, MDI, DESY Hamburg; 27. 08. 2010
Temperature distribution P 1 Airflow switched off. Lower Temperature because of lower power Measured 70°C, simulation lower by 16% D. Lipka, MDI, DESY Hamburg; 27. 08. 2010
Setup: smaller gap Smaller gap = 1. 7 mm should reduce energy loss Gap near chamfer to result in good energy transmission Kloss = 15. 1 V/n. C D. Lipka, MDI, DESY Hamburg; 27. 08. 2010
Eigenmode distribution Field amplitude near gap D. Lipka, MDI, DESY Hamburg; 27. 08. 2010
Temperature distribution P 2 Maximum temperature reduced from 106 °C to 55°C (remember: simulation underestimates temperature) D. Lipka, MDI, DESY Hamburg; 27. 08. 2010
Setup without coating gap = 1. 7 mm symmetrically below ceramic Ceramic without coating to result in higher energy transmission Kloss = 26. 6 V/n. C, because gap is deeper without coating D. Lipka, MDI, DESY Hamburg; 27. 08. 2010
Eigenmode distribution Field has poor accuracy, because space between bellow and iron included; highest amplitude near left gap D. Lipka, MDI, DESY Hamburg; 27. 08. 2010
Temperature distribution P 2 Maximum temperature reduced from 106 °C to 85°C (remember: simulation underestimates temperature) D. Lipka, MDI, DESY Hamburg; 27. 08. 2010
Setup: with coating and add shielding gap = 8. 2 mm like origin, coating actives Shielding of resonator Kloss reduced to 4. 4 V/n. C, because influence of resonator avoided No resonance found below cutoff (2. 44 GHz) D. Lipka, MDI, DESY Hamburg; 27. 08. 2010
Temperature distribution P 2 Maximum temperature reduced from 106 °C to 31°C (remember: simulation underestimates temperature) D. Lipka, MDI, DESY Hamburg; 27. 08. 2010
Summary • Simulated temperature distribution • Temperature underestimated, but trend is in agreement • Smaller gap and shielding of resonator reduces temperature • Suggestion: smaller gap and/or close space between bellow and shielding D. Lipka, MDI, DESY Hamburg; 27. 08. 2010 origin
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