D. Lipka, MDI, DESY Hamburg; Temperature Simulation DCCT at PETRA III D. Lipka, MDI, DESY Hamburg

D. Lipka, MDI, DESY Hamburg; Problem Two cases of operation with different temperatures at the current monitor observed Case 1: I1=85 mA, N=160 Bunches gives about 70°C Case 2: I2=65 mA, N=40 Bunches gives about 130°C Questions: Why case 2 higher temperature? Why temperature high?

D. Lipka, MDI, DESY Hamburg; Answer Problem 1 Power P = I Q k loss I is mean beam current Q is charge = I  t  t is bunch distance = t / N t is PETRA III revolution time = µs k loss is voltage loss per charge for a structure Result in P = I 2 t k loss / N P1/P2 = 0.43 Because P2 is higher the temperature is higher! Compare: P E-XFEL,max /P2=0.0001

D. Lipka, MDI, DESY Hamburg; Setup DCCT PEEK AlMg3 µ-metal Stainless Steel CuBe Iron ceramic In CST imported model from Annette Brenger

D. Lipka, MDI, DESY Hamburg; 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; 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; Wakefield Simulation Mesh cells around bellow and ceramic: Simulation tool can not resolve bellow and coating perfect! Anyhow: k loss =39.1 V/nC ->P1=13.6 W, P2=31.7 W

D. Lipka, MDI, DESY Hamburg; Eigenmode Simulation Field distribution between bellow and shielding Setup: only vacuum part Field distribution

D. Lipka, MDI, DESY Hamburg; Temperature Distribution P2 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; Temperature distribution shortened P2 Here the distance to cooling is only 200 mm, T max =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; Temperature distribution P2 with airflow Here the simulation box increased with cooling at x min,max and y min,max, T max reduces from 106°C to 87.5 °C

D. Lipka, MDI, DESY Hamburg; Temperature distribution P1 Airflow switched off. Lower Temperature because of lower power Measured 70°C, simulation lower by 16%

D. Lipka, MDI, DESY Hamburg; Antenna in hollow space Similar antenna in space simulation applied to compare energy Results in Voltage vs Time, calculated in power and integrated gives energy between shielding and bellow: E i1 between bellow and iron: E o1 Here only relative values to compare energy in each space: E i1 /E o1 = 194 That means only a fraction of lossed energy contribute to signal from DCCT

D. Lipka, MDI, DESY Hamburg; Setup: smaller gap Smaller gap = 1.7 mm should reduce energy loss Gap near chamfer to result in good energy transmission K loss = 15.1 V/nC

D. Lipka, MDI, DESY Hamburg; Eigenmode distribution Field amplitude near gap

D. Lipka, MDI, DESY Hamburg; Temperature distribution P2 Maximum temperature reduced from 106 °C to 55°C (remember: simulation underestimates temperature)

D. Lipka, MDI, DESY Hamburg; Results with smaller gap E i2 /E o2 = 0.33 because antenna in chamfer leewards E o2 /E o1 = 0.35 because lower energy loss of beam and oscillation contributes to signal

D. Lipka, MDI, DESY Hamburg; Setup without coating gap = 1.7 mm symmetrically below ceramic Ceramic without coating to result in higher energy transmission K loss = 26.6 V/nC, because gap is deeper without coating

D. Lipka, MDI, DESY Hamburg; Eigenmode distribution Field has poor accuracy, because space between bellow and iron included; highest amplitude near left gap

D. Lipka, MDI, DESY Hamburg; Temperature distribution P2 Maximum temperature reduced from 106 °C to 85°C (remember: simulation underestimates temperature)

D. Lipka, MDI, DESY Hamburg; Results: transmission E i1 /E o1 = 194available design E i2 /E o2 = 0.33 best energy transfer E i3 /E o3 = 47 more energy in resonator E o2 /E o1 = 0.35 but low signal amplitude E o3 /E o1 = 0.82 better amplitude

D. Lipka, MDI, DESY Hamburg; Setup: with coating and add shielding gap = 8.2 mm like origin, coating actives Shielding of resonator K loss reduced to 4.4 V/nC, because influence of resonator avoided No resonance found below cutoff (2.44 GHz)

D. Lipka, MDI, DESY Hamburg; Temperature distribution P2 Maximum temperature reduced from 106 °C to 31°C (remember: simulation underestimates temperature)

D. Lipka, MDI, DESY Hamburg; Results: transmission E i1 /E o1 = 194available design E i2 /E o2 = 0.33 best energy transfer E i3 /E o3 = 47 more energy in resonator E i4 /E o4 = 11should be zero, but meshing not perfect E o2 /E o1 = 0.35 but low signal amplitude E o3 /E o1 = 0.82 better amplitude E o4 /E o1 = almost no signal

D. Lipka, MDI, DESY Hamburg; 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 origin