Status of the Cband injector design D AlesiniA
Status of the C-band injector design D. Alesini/A. Vannozzi (LNF-INFN, Frascati) on behalf of the WP 3 C-band injector working team* * D. Alesini, A. Vannozzi, G. Muti, F. Cardelli, E. Gazis, E. Trachanas, M. Croia, A. Gallo, M. Diomede, M. Ferrario, C. Vaccarezza, A. Giribono, L. Ficcadenti, J. Scifo, L. Pellegrino, B. Spataro.
A C-BAND INJECTOR LAYOUT Considered layout (not in scale) Gun solenoid TW structures solenoids 2 C-band TW structures, with solenoid around, operating at 40 MV/m average accelerating gradient (as example, PSI-like structures with 1 klystron every 2 sections) 2 m 1. 6 cell RF gun operating at 200 -240 MV/m cathode peak field X-band accelerating module Linearizer (X, Ka? )
DESIGN CRITERA FOR THE C-BAND GUN The design and fabrication of the new gun has been driven by the same criteria used in the design of room temperature high gradient X band structures developed in the last 20 years in the framework of linear collider projects (NLC, JLC and CLIC). There are four main quantities that play a crucial role in the BDR control: the peak electric field, the modified Poynting vector (Sc), the RF pulse length (tp) and the pulsed heating ( T). The gun has been designed keeping under control these quantities. Standard couplers on the full cell cannot be adopted because of the high pulsed heating due to the high magnetic field on the coupling holes and, therefore, a mode launcher type coupler has been considered. To reduce the dipole and quadrupole field components induced in the mode launcher a modified design of the mode launcher itself will be necessary. Holes on the mode launcher coupler to allow the laser injection will be also implemented. Mode launcher (with comp. of quad. component)
C-BAND GUN POWERING SCHEME RF pulses of few tens of MW at 200 ns allow reaching Ecath>200 MV/m. Because of its higher efficiency, a C-band RF Gun is also suitable for application requiring repetition rates in the 500 Hz ÷ 1 k. Hz range Moreover, to feed the SW gun a C-band circulator is necessary to protect the klystron from the power reflections during transients (a commercial available C band circulator exists and will be purchased to allow the high power tests). <0. 200 s 40 MW KLY circ [1] D. Alesini et al. , TUPTS 024, IPAC 19 Ecath 240 MV/m Δf 0 - ≈ 90 MHz Q 0 12000 3 Pdiss @240 MV/m 12 MW 69 [MV/m. MW 0. 5] PIN @240 MV/m 31 MW T @ 200 ns <30 o. C RF pulse length <200 ns Av diss power 2000 -200 W Rep. Rate 1000 -100 Hz
FULL C-BAND GUN 2 D DESIGN
FULL C-BAND GUN 2 D DESIGN: RESULTS (@200 MV/m) (@240 MV/m) fπ ∆f |(Es/Ec)| |Sc| 5717 MHz 82 MHz 0. 904 4. 544 W/µm 2 6. 543 W/µm 2 Ec/√P Q 0 ∆T @180 ns 12289 21 deg 30 deg
3 D ELECTROMAGNETIC DESIGN laser A first version of the mode launcher coupler (w/o quadrupole compensation) has been designed. The S 11 put in evidence the presence of the only two modes. The position of the coupler can be varied according to the BD/solenoid design. On axis injection with external mirrors is possible. BD calculations considering the tail of the electric field into the circular waveguide have to be done laser
1 KHz OPERATION In this case we reduce the RF pulse but we are dominated by the modulator transients. Looking at the values of the high power C-band klystron Canon (Toshiba) E 37212 that are specified for 100 Hz, 50 MW, t. RF_MAX=2. 5 s, ttrans=2. 5 s, we obtain Pcoll_MAX 58 k. W. Assuming equivalent transients given by solid state modulators similar to that measured on SPARC C-band klystrons (ttrans 1. 2 s) we obtain: Mode launcher case
THERMAL ANALISYS (1 KHz REGIME) We started a thermo-mechanical analysis to investigate the feasibility of the 1 KHz operation. We use the ansys code. In the figure a preliminary calculation in the case of a 1 KW dissipated power is shown. Courtesy L. Pellegrino
FUNDING PROGRAMS FUNDED BY CSN V INFN: 190 KEuro Realization and test of one gun+circulator RF Test 3 years program (2020 -2022) WAITING FOR AN ANSWER
PROGRAM AND TIMESCHEDULE: TUAREG 1 st year (2020): -gun electromagnetic and thermo-mechanical design; -RF gun order (end 2020) -mode launcher electromagnetic and mechanical design; 2 nd year (2021): -mode launcher order (1 st half 2021) -circulator order (2 nd half 2021, delivery 9 months, CML) -RF gun low power test (end 2021) 3 rd year (2022): -RF gun+mode launcher low power RF test (1 st half 2022) -order of few waveguide components for the high power test (depending on the location INFN or PSI) -final high power test (end 2022) All other studies and simulations activities run in parallel (solenoids, dark current, etc…) March-June 2020: first ARIES 2 output expected In the framework of the ARIES 2 co-funding program the project “C-guns” has been submitted. 4 years program 3 Institutions: INFN (coord. ), PSI, La Sapienza 1 Industry (COMEB, Italy) Goals: design and test 2 different C-band guns: SW (INFN), TW (PSI) Design and test the solenoid for the SW Design and test the diagnostics for dark current and beam characterization The Gruppo V financial request can be remodulated according to the results of the ARIES 2 competition (INFN Aries 2 request: 200 k. Euro)
CONCLUSIONS AND FUTURE WORK 1) C-band GUN Design: a) Mode launcher with quadrupole component compensation b) Complete the Thermo-mechanical analysis c) Mechanical drawing and prototypes. . . 2) Other parallel activities: dark current studies, laser injection system, …
SOLENOID FOR THE C-BAND GUN Bucking Coil Axial symmetric 2 D simulations have been performed with Poisson Superfish. Integrated field the same of the SPARC_LAB S-band gun solenoid. Bucking coil for the cancellation of the field on cathode (from almost 360 G to ≈1 G). Cathode position (110. 5 mm from the solenoid center)
SOLENOID ON THE C-BAND ACCELERATING STRUCTURE Work done in collaboration with Emmanouil Trachanas
SOLENOID ON THE C-BAND ACCELERATING STRUCTURE Work done in collaboration with Emmanouil Trachanas Unique Shield configuration
SOLENOID ON THE C-BAND ACCELERATING STRUCTURE Work done in collaboration with Emmanouil Trachanas
SOLENOID ON THE C-BAND ACCELERATING STRUCTURE Work done in collaboration with Emmanouil Trachanas Separate Shield configuration
SOLENOIDS FUTURE ACTIONS GUN SOLENOID More accurate check with beam dynamics team Investigate other configuration with: Solenoid smaller bore aperture (15 -20 mm). Same distance from the cathode of the actual SPARC_LAB configuration (204 mm). Probably bucking coil no needed. C-BAND ACCELERATING STRUCTURE SOLENOID More accurate check with beam dynamics team Investigation of separate shield or unique shield configuration
CONCLUSIONS AND FUTURE WORK 1) C-band GUN Design: a) Mode launcher with quadrupole component compensation b) Complete the Thermo-mechanical analysis c) Mechanical drawing and prototypes. . . 2) Other parallel activities: dark current studies, laser injection system, … 3) Solenoid design: a) Complete the design of the gun solenoid/explore the different options b) TW solenoid Investigation of separate shield or unique shield configuration c) 3 D design…
- Slides: 19