HIGHPOWER 12 GHZ KLYSTRON DESIGN FOR CLIC PROJECT

HIGH-POWER 12 GHZ KLYSTRON DESIGN FOR CLIC PROJECT EUCARD 2 – INNOVATIVE RADIO FREQUENCY (RF) TECHNOLOGIES SUB-TASK 12. 3. 2 Antoine MOLLARD www. cea. fr EUCARD 2 WP 12 MEETING 8 -9 APRIL 2015 - DESY

OUTLINE • High-efficiency klystron « Kladistron » project • CLIC Project & CTF 3 • 12 GHz High-efficiency klystron • High-efficiency 4. 9 GHz klystron design : TH 2166 Kladistron • TH 2166 Electron Gun • Cavities • Thales Electron Devices klystron TH 2166 • • • Simulations (AJDisk, Klys 2 D) Tests & Conditioning Preliminary “Kladistron 2166” Design • Conclusion & Outlook Antoine Mollard – Eu. Card 2 WP 12 2

KLADISTRON PROJECT CLIC PROJECT & CTF 3 WP 12 : Innovative RF Technologies 2013 - 2017 « In this sub-task, CEA will develop and search for innovative concepts of X band RF power sources and components. The objective is to propose affordable and reliable solutions for future testing capabilities for the CLIC accelerating structures. The task includes the design and the fabrication of prototype RF devices to demonstrate the feasibility of the new concepts proposed. » Budget available to build a (small) part of the RF power source or component Collaboration with THALES ELECTRON DEVICES & CERN Antoine Mollard – Eu. Card 2 WP 12 3

KLADISTRON PROJECT 12 GHZ HIGH-EFFICIENCY KLYSTRON We propose to study and design a 12 GHz single beam klystron • Peak power of 10 to 12 MW with a pulse duration of 4. 5 µs. • Compatible with the Scandinova modulator ordered for XBOX 3 in order to fully qualify the klystron at CERN. • • Vk = 170 k. V Ik = 100 A µP = 1. 4 µA/V 1. 5 Efficiency > 70 % -> Pout = 12 MW A new klystron concept is required If these challenging performances are achieved, the 6 MW Toshiba klystron could be replaced by our 12 MW klystron and would double the testing capability of XBOX 3 Antoine Mollard – Eu. Card 2 WP 12 4

KLADISTRON PROJECT 12 GHZ HIGH-EFFICIENCY KLYSTRON 12 GHz « KLADISTRON » 4. 9 GHz « KLADISTRON » for feasibility demonstration Antoine Mollard – Eu. Card 2 WP 12 5

WHAT IS A « KLADISTRON » ? A Kladistron (Kl-adi(adiabatic)-stron) is a high-efficiency klystron with a large number of cavities (twice as many cavities as in a conventional klystron) The idea is: Instead of giving a “large kick” to the beam in a small number of cavities Giving a “soft kick” to the beam in a large number of cavities Antoine Mollard – Eu. Card 2 WP 12 6

12 GHZ HIGH-EFFICIENCY KLYSTRON AJDISK SIMULATIONS (CEA) 10 cavities Efficiency 67. 2 % Length 197 mm 20 cavities Efficiency 78 % Length 285 mm In the design proposed, the cavities are weakly coupled to the beam (low R/Q) and largely detuned to avoid strong bunching Antoine Mollard – Eu. Card 2 WP 12 7

HIGH-EFFICIENCY 4. 9 GHZ KLYSTRON DESIGN TH 2166 KLADISTRON TH 2166 klystron Designed for Mainz Microtron. Thales TH 2166 Klystron Frequency 4. 9 GHz Pout 60 k. W Efficiency 50% Vk 26 k. V µP 1. 066 Bmax 0. 27 T Gain >40 d. B Ncavities 6 Interaction line length 243 mm Antoine Mollard – Eu. Card 2 WP 12 8

HIGH-EFFICIENCY 4. 9 GHZ KLYSTRON DESIGN TH 2166 KLADISTRON TH 2166 klystron Designed for Mainz Microtron. Thales TH 2166 Klystron CEA TH 2166 « Kladistron » Frequency 4. 9 GHz Pout 60 k. W ~80 k. W Efficiency 50% > 70% Vk 26 k. V µP 1. 066 Bmax 0. 27 T Gain >40 d. B Ncavities 6 15 Interaction line length 243 mm Antoine Mollard – Eu. Card 2 WP 12 9

TH 2166 KLADISTRON input cavity Intermediate cavities gun output cavity and window The klystron TH 2166 collector solenoid gun N(>3) new intermediate cavities with lower r/Q The elements we keep collector ? solenoid The elements we will design and fabricate Antoine Mollard – Eu. Card 2 WP 12 10

TH 2166 KLADISTRON DEVELOPMENT PLAN Start No 1 D Simulations Codes ACHIEVED Benchmarking Design No η>70%? G>40 d. B? Yes Tests Manufacturing 2 D, 3 D simulations Solenoid Kladistron 12 GHz Antoine Mollard – Eu. Card 2 WP 12 11

TH 2166 KLADISTRON DEVELOPMENT PLAN • Benchmarking : test the reliability of simulation software • Same results ? • Trustworthy results? • 1 D Simulations • How many cavities? • Which frequencies, R/Q, Q 0 ? • 2 D, 3 D Simulations • Electrons behavior • Electric field shape • Electrons bunching improvement • Manufacturing • Tests & Conditioning • Design Antoine Mollard – Eu. Card 2 WP 12 12

TH 2166 ELECTRON GUN OPTIC 2 D (THALES CODE) & CST SIMULATION Cathode potential is given. Beam shape & current are computed. No magnetic field Optic 2 D Software Vk (k. V) Zwaist (mm) I (A) µP Optic 2 D 26 40. 77 4. 46 1. 066 CST 26 34. 01 4. 03 0. 961 CST Antoine Mollard – Eu. Card 2 WP 12 13

TH 2166 ELECTRON GUN OPTIC 2 D BEAM Input Klys 2 D Beam Ripple Beam Radius/Drift Radius Vk (k. V) I (A) µP 11. 07% 59. 04% 26 4. 47 1. 066 Antoine Mollard – Eu. Card 2 WP 12 14

INTERACTION CODES • KLYS 2 D • • Lumped circuit Thales Electron Devices (TED) 2 D-code Ring model Focusing magnetic field needed Klystron cavities characterized by lumped circuits (f, R/Q, Q 0, Qext) • AJDisk • • SLAC 1 D-code Disk model No focusing magnetic field needed Klystron cavities characterized partly by lumped circuits (f, R/Q, Q 0, Qext) and transit time factor (TTF or M) Antoine Mollard – Eu. Card 2 WP 12 15

TH 2166 – AJDISK & KLYS 2 D SIMULATIONS MODULATION CURRENTS AJDisk harm 1 In/I 0 Klys 2 D 1. 6 1. 4 1. 2 1 0. 8 0. 6 0. 4 0. 2 0 -3. 000 E+01 harm 2 Gaps 2. 000 E+01 7. 000 E+01 1. 200 E+02 Z MM 1. 700 E+02 2. 200 E+02 2. 700 E+02 Code Frequency (GHz) U_k (k. V) I_beam (A) P_in (W) (satutration) P_out (k. W) Efficiency Gain (d. B) AJDisk 4. 900 26 4. 3 2. 5 59. 84 54. 23% 43. 79 Klys 2 D 4. 900 26 4. 3 3 56. 55 50. 58% 42. 75 Antoine Mollard – Eu. Card 2 WP 12 16

TH 2166 – AJDISK & KLYS 2 D SIMULATIONS ELECTRONS VELOCITIES AJDisk Klys 2 D Magnetic field Code Frequency (GHz) U_k (k. V) I_beam (A) P_in (W) (satutration) P_out (k. W) Efficiency Gain (d. B) AJDisk 4. 900 26 4. 3 2. 5 59. 84 54. 23% 43. 79 Klys 2 D 4. 900 26 4. 3 3 56. 55 50. 58% 42. 75 Antoine Mollard – Eu. Card 2 WP 12 17

SIMULATION & TESTS RESULTS – TH 2166 70 60 Efficiency 50 AJDisk 40 30 Measured Magnetic Field & Klys 2 D Beam 20 10 0 0 0. 5 1 1. 5 2 2. 5 3 3. 5 Pin (W) Results I (A) Vk (k. V) P_in (W) (saturation) P_out (k. W) µP η G (d. B) AJDisk 4. 3 26 2. 5 59. 84 1. 03 54. 23% 43. 79 Klys 2 D (Thales) – Measured Magnetic Field & Klys 2 D Beam 4. 3 26 3 56. 55 1. 03 50. 58% 42. 75 Antoine Mollard – Eu. Card 2 WP 12 18

TH 2166 TESTS & CONDITIONING AT THALES 1. 2. 3. 4. Control Cathode heating voltage Cathode voltage HF signal (power/freq) Current of the foc. solenoids Power measurements A. Inside the collector: – – By current measurement By calorimetry B. In the main part: – – By current measurement By calorimetry 4 3 2 C B 1 D C. In the output cavity D. In the focusing coil Antoine Mollard – Eu. Card 2 WP 12 19 A

SIMULATION & TESTS RESULTS – TH 2166 70 60 AJDisk Efficiency 50 Measured Magnetic Field & Klys 2 D Beam 40 30 Measured Magnetic Field & Optic 2 D Beam 20 Tests 10 0 0 0. 5 1 1. 5 2 2. 5 3 3. 5 Pin (W) Results I (A) Vk (k. V) P_in (W) (saturation) P_out (k. W) µP η G (d. B) AJDisk 4. 3 26 2. 5 59. 84 1. 03 54. 23% 43. 79 Klys 2 D (Thales) – Measured Magnetic Field & Optic 2 D Beam 4. 47 26 0. 6 67. 32 1. 03 58. 24% 50. 50 Klys 2 D (Thales) – Measured Magnetic Field & Klys 2 D Beam 4. 3 26 3 56. 55 1. 03 50. 58% 42. 75 Tests 4. 35 25. 3 0. 246 50. 10 1. 08 45. 54% 53. 09 Antoine Mollard – Eu. Card 2 WP 12 20

KLADISTRON PROJECT WORK IN PROGRESS 6 cav 15 cav Antoine Mollard – Eu. Card 2 WP 12 21

TH 2166 KLADISTRON – AJDISK & KLYS 2 D SIMULATIONS MODULATION CURRENTS WORK IN PROGRESS Klys 2 D In/I 0 AJDisk 1. 6 1. 4 1. 2 1 0. 8 0. 6 0. 4 0. 2 0 -3. 000 E+01 Not at saturation harm 1 harm 2 Gaps 2. 000 E+01 7. 000 E+01 1. 200 E+02 Z MM 1. 700 E+02 2. 200 E+02 2. 700 E+02 Code Frequency (GHz) U_k (k. V) I_beam (A) P_in (W) (satutration) P_out (k. W) Efficiency Gain (d. B) AJDisk 4. 900 26 4. 3 8 72. 00 66. 75% 39. 69 Klys 2 D 4. 900 26 4. 3 Antoine Mollard – Eu. Card 2 WP 12 22

TH 2166 KLADISTRON – AJDISK & KLYS 2 D SIMULATIONS ELECTRONS VELOCITIES WORK IN PROGRESS AJDisk Klys 2 D Not at saturation Code Frequency (GHz) U_k (k. V) I_beam (A) P_in (W) (satutration) P_out (k. W) Efficiency Gain (d. B) AJDisk 4. 900 26 4. 3 8 72. 00 66. 75% 39. 69 Klys 2 D 4. 900 26 4. 3 Antoine Mollard – Eu. Card 2 WP 12 23

SIMULATION & TESTS RESULTS TH 2166 KLADISTRON WORK IN PROGRESS 80 70 60 AJDisk 50 Measured Magnetic Field & Klys 2 D Beam 40 30 Klys 2 D Magnetic Field & Beam 20 10 0 0 2 4 6 8 10 12 Results I (A) Vk (k. V) P_in (W) (saturation) P_out (k. W) µP η G (d. B) AJDisk 4. 3 26 8 72. 00 1. 03 66. 75% 39. 69 Klys 2 D (Thales) – Klys 2 D Magnetic Field & Beam 4. 3 26 10 64. 37 1. 03 57. 58% 38. 09 Klys 2 D (Thales) – Measured Magnetic Field & Klys 2 D Beam 4. 3 26 Antoine Mollard – Eu. Card 2 WP 12 24

CONCLUSION ON SIMULATIONS OF TH 2166 & TH 2166 KLADISTRON WORK IN PROGRESS 80 70 60 Efficiency 50 Klys 2 D TH 2166 40 Klys 2 D TH 2166 Kladistron AJDisk TH 2166 30 AJDisk TH 2166 Kladistron 20 10 0 0 1 2 3 4 5 6 7 8 9 Pin (W) Antoine Mollard – Eu. Card 2 WP 12 25

CONCLUSION & OUTLOOK The RF tubes (gun & interaction) codes benchmarking with Thales TH 2166 4. 9 GHz klystron is achieved. We got promising resluts with our initial TH 2166 « kladistron » design (AJDisk software). q This design need improvements with Klys 2 D. q 2 D/3 D (Magic) simulations will let us foresee more precisely electron beam behaviour and cavities/beam interactions. The TH 2166 « kladistron » final design is scheduled for next summer and it will be ready to test by the end of 2015. We will be able to start 12 GHz « kladistron » design next year. Antoine Mollard – Eu. Card 2 WP 12 26

Thank you for your attention. Antoine Mollard – Eu. Card 2 WP 12 27

THE CEA TEAM CEA permanent staff Franck PEAUGER Juliette PLOUIN Barbara DALENA with help of: Antoine CHANCÉ Beam dynamics, user of Tracewin and Warp Antoine MOLLARD Antoine Mollard – Eu. Card 2 WP 12 28