Notkestrasse 85, 22607 Hamburg, Germany Parameter Set for High Duty Factor and CW Operation of a TTF-like Cryomodule; An Example* Jacek Sekutowicz DESY- MPY Notkestrasse 85, 22607 Hamburg, Germany * Work supported by EU under contract No. 011935 (EUROFEL) WG5: TTF Meeting, KEK, Tsukuba, September 25-28, 2006. Jacek Sekutowicz

WG5: TTF Meeting, KEK, Tsukuba, September 25-28, 2006. INTRODUCTION In following I will talk on “Accelerating Unit” The Unit consists of: One TTF-like Cryomodule (eight 9-cell sc cavities) + RF-transmitter supplying the RF-power to all 8 cavities. WG5: TTF Meeting, KEK, Tsukuba, September 25-28, 2006. Jacek Sekutowicz

WG5: TTF Meeting, KEK, Tsukuba, September 25-28, 2006. INTRODUCTION General Remarks CW and near-CW operation require low emittance SRF electron source (1nC @ 1 µrad @ 0.01-1 MHz) which does not exist at present There are 3 improvements we need to make in the future for the cw or near-cw operation: Increase intrinsic Q of sc cavities ► this lowers the cost of a cryogenic plant Reduce microphonics ► this lowers the cost of a RF-system Upgrade RF-source for cw or near-cw operation ► this also lowers cost of the RF-system All three seem to be feasible. WG5: TTF Meeting, KEK, Tsukuba, September 25-28, 2006. Jacek Sekutowicz

WG5: TTF Meeting, KEK, Tsukuba, September 25-28, 2006. ACCELERATING UNIT Transmitter 2 x 60 kW IOT 60 kW Driver 380 W Directional coupler Load Circulator Quad. 38 kV Power Supply Based on EUROFEL DS5 Studies by the CPI Company WG5: TTF Meeting, KEK, Tsukuba, September 25-28, 2006. Jacek Sekutowicz

WG5: TTF Meeting, KEK, Tsukuba, September 25-28, 2006. ACCELERATING UNIT Transmitter 120 kW Quad. IOT 120 kW Driver 760 W Directional coupler Load Circulator 47 kV Based on EUROFEL DS5 Studies by the CPI Company WG5: TTF Meeting, KEK, Tsukuba, September 25-28, 2006. Jacek Sekutowicz

WG5: TTF Meeting, KEK, Tsukuba, September 25-28, 2006. ACCELERATING UNIT Assumption 1: Cryogenic Dynamic Load 30W @ 1.8 K Max Pfor = 15.0 kW / cavity Max Pin = 14.5 kW / cavity Max Pbeam = 11.6 kW / cavity Charge/Bunch: q = 1 nC WG5: TTF Meeting, KEK, Tsukuba, September 25-28, 2006. Jacek Sekutowicz

WG5: TTF Meeting, KEK, Tsukuba, September 25-28, 2006. ACCELERATING UNIT Assumption 2: We will keep <cryogenic load> constant vs. Eacc DF scales ~ 1/( Eacc)2 250 ms Pfor Pfor 15 kW 15 kW t 1s t 6 MV/m 12 MV/m WG5: TTF Meeting, KEK, Tsukuba, September 25-28, 2006. Jacek Sekutowicz

WG5: TTF Meeting, KEK, Tsukuba, September 25-28, 2006. ACCELERATING UNIT Assumption 3: We will keep Pbeam constant vs. Eacc Ibeam ~ 1/Eacc q = 1nC stays constant but tb ~ Eacc q [nC] t 1 6 MV/m tb= 0.54 µs t 12 MV/m q [nC] 1 tb= 1.08 µs WG5: TTF Meeting, KEK, Tsukuba, September 25-28, 2006. Jacek Sekutowicz

Dynamic cryogenic load 30 W/Unit at 1.8-2 K. ACCELERATING UNIT Assumptions Summary Dynamic cryogenic load 30 W/Unit at 1.8-2 K. RF power transmitter supplies 120 kW/Unit. 20% of RF-power is reserved for the phase and amplitude stabilization. 3% RF-power is lost in the RF distribution system. Single bunch has ~1 nC charge. Table on the next slide contains data for the presented Unit and for a XFEL-like linac with 120 Units. WG5: TTF Meeting, KEK, Tsukuba, September 25-28, 2006. Jacek Sekutowicz

WG5: TTF Meeting, KEK, Tsukuba, September 25-28, 2006. ACCELERATING UNIT Energy gain /Accelerating Unit [MeV] 50 75 100 125 150 175 200 Eacc [MV/m] 6.01 9.01 12.02 15.02 18.03 21.03 24.04 Qo [1010] 2.0 Total Loss at 2K/cryomodule for DF = 100% [W] 29.6 43.2 67.2 100.2 141.4 190.7 247.7 Duty Factor [%] 69.4 44.6 29.9 21.2 15.7 12.1 Beam time [ms] 1000 693 444 297 208 152 114 Pulse length 694 446 299 212 157 121 Beam current [mA] 1.86 1.24 0.93 0.74 0.62 0.53 0.46 Bunch spacing when charge/bunch = 1nC [µs] 0.54 0.81 1.08 1.35 1.62 1.89 2.16 Number of 1 nC bunches/s [106] 1.855 0.857 0.412 0.220 0.129 0.081 0.053 Opt. Qext to keep power ≤ 14.5 kW/cavity 3.1 6.7 11 14 20 27 36 Max. allowed microphonics peak-peak [Hz] 34 24 18 Total RF-peak power/cavity: beam + microphonics [kW] 12.4 13.2 14.5 XFEL Energy for 116 acc. units [GeV] 5.8 8.7 11.6 17.4 20.3 23.2 WG5: TTF Meeting, KEK, Tsukuba, September 25-28, 2006. Jacek Sekutowicz

WG5: TTF Meeting, KEK, Tsukuba, September 25-28, 2006. ACCELERATING UNIT DF and Number of Bunches/s vs. Energy Gain WG5: TTF Meeting, KEK, Tsukuba, September 25-28, 2006. Jacek Sekutowicz

WG5: TTF Meeting, KEK, Tsukuba, September 25-28, 2006. ACCELERATING UNIT Power/cavity vs. Microphonics WG5: TTF Meeting, KEK, Tsukuba, September 25-28, 2006. Jacek Sekutowicz

WG5: TTF Meeting, KEK, Tsukuba, September 25-28, 2006. ACCELERATING UNIT Optimum Qext vs. Microphonics WG5: TTF Meeting, KEK, Tsukuba, September 25-28, 2006. Jacek Sekutowicz

WG5: TTF Meeting, KEK, Tsukuba, September 25-28, 2006. ACCELERATING UNIT The technical goals: Intrinsic Q = 2∙1010 for Eacc in the range from 6 - 24 MV/m. Transmitter (IOT) delivering 120 kW. Microphonics p-p < 24 Hz for nominal operation Eacc <18 MV/m and < 14 Hz for the extended operation between 18–24 MV/m. are feasible and can be reached in near future. In case of technical difficulties: Lower Q can be compensated with more cryogenic power or/and shorter pulses. 120 kW IOT can be replaced with 4 existing or 2 upgraded tubes. Microphonics can be compensated with more RF-power. WG5: TTF Meeting, KEK, Tsukuba, September 25-28, 2006. Jacek Sekutowicz

WG5: TTF Meeting, KEK, Tsukuba, September 25-28, 2006. CONCLUSIONS Two basic assumptions Dynamic cryogenic load of 30 W/Unit at 1.8-2 K. RF power of 120 kW. led to operating parameter set for the 8-cavity cryomodule with one power source allowing for acceleration of : 5.30∙104 @ 1nC bunches at Energy Gain 200 MeV/Unit (pulse = 121ms) up to 1.86∙106 @ 1nC bunches at Energy Gain 50 MeV/Unit (cw) with flexibility in the beam time structure resulting from the operation in cw or near-cw mode. WG5: TTF Meeting, KEK, Tsukuba, September 25-28, 2006. Jacek Sekutowicz

WG5: TTF Meeting, KEK, Tsukuba, September 25-28, 2006. CONCLUSIONS: RF-SOURCE FOR CW OR NEAR-CW OPERATION It seems at present that Inductive Output Tubes (IOT) could be very attractive RF-sources for the cw or near-cw operation of linacs driving photon sources: IOTs are very compact devices Long life time (up to 95000 hours of operation) Can operate in cw mode and pulse mode, with arbitrary pulse length Do not take AC energy between pulses Further development of IOTs should lead to higher output power Higher output power (L-band 32 kW cw) Higher gain (at present 20-22 dB) Higher overall efficiency (at present ~65%) WG5: TTF Meeting, KEK, Tsukuba, September 25-28, 2006. Jacek Sekutowicz

WG5: TTF Meeting, KEK, Tsukuba, September 25-28, 2006. CONCLUSIONS: RF-SOURCE FOR CW OR NEAR-CW OPERATION State-of-the-art IOTs 1.3 GHz IOTs CPI Pout [kW] 32 (85 pulse) Gain [dB] 21 η [%] > 65 WG5: TTF Meeting, KEK, Tsukuba, September 25-28, 2006. Jacek Sekutowicz

WG5: TTF Meeting, KEK, Tsukuba, September 25-28, 2006. CONCLUSIONS: RF-SOURCE FOR CW OR NEAR-CW OPERATION CPI works on 60kW and 120 kW tube at 1300 MHz in the frame of EUROFEL studies 32 kW 1300 MHZ IOT Preliminary parameters of 120 kW IOT (Modeling by H. Bohlen) Parameter Unit Pout= 60 kW (cw and pulse ok) Pout= 120 kW (pulse ok, cw?) Voltage [kV] 38 47 Current [A] 2.5 3.7 Gain [dB] 22 Efficiency [%] 64 72.8 New R&D Upgrade of the existing tube Courtesy of CPI : H. Bohlen, Y. Li and P. Krzeminski WG5: TTF Meeting, KEK, Tsukuba, September 25-28, 2006. Jacek Sekutowicz

Single Crystal 2.2 GHz Niobium Cavity CONCLUSIONS: INTRINSIC Q OF SC CAVITIES State-of-the-art Intrinsic Q Single Crystal 2.2 GHz Niobium Cavity Test #2: post-purification heat treatment at 1250 C for 10 hrs, 100 µm BCP, HPR Courtesy P. Kneisel JLab Courtesy P. Kneisel JLab WG5: TTF Meeting, KEK, Tsukuba, September 25-28, 2006. Jacek Sekutowicz

WG5: TTF Meeting, KEK, Tsukuba, September 25-28, 2006. CONCLUSIONS: INTRINSIC Q OF SC CAVITIES State-of-the-art Intrinsic Q Courtesy P. Kneisel JLab WG5: TTF Meeting, KEK, Tsukuba, September 25-28, 2006. Jacek Sekutowicz