RF scheme of electron linear accelerator with energy

RF scheme of electron linear accelerator with energy 200 -500 Me. V Levichev A. E. Budker Institute of Nuclear Physics SB RAS

Introduction

Debuncher-monohramator

Accelerating structure. 1 – Regular cell, 2 – Wave type transformer, 3 – Connection cell, 4 – Connection diaphragm, 5 – Structure frame with cooling system.

Accelerating structure BINP produced accelerating structure. Accelerating cells and wave type transformers.

Basic parameters of BINP made accelerating structures Operating frequency f 2855. 5 МHz Operating mode Unloaded quality factor Group velocity Shunt impedance Unloaded time Q 0 Vgr Rsh 0 = 2 Q 0/ 1. 32 104 0. 021 C 51 МОhм/м 1. 47 μs Attenuation parameter = 1/( 0 Vgr) 0. 108 1/м Integrated attenuation parameter L 0. 316 Filling time Tf =L/ Vgr 0. 465 μs Period 34. 98 мм Inner diameter of the cell cavity 83. 8 мм Iris aperture diameter 25. 9 мм Iris thickness 6 мм Overvoltage coefficient 1. 7

RF power source Picture of TH 2100 klystrons series. Basic parameters of TH 2128 C/D klystron. Operating frequency 2856 MHz Peak output power 45. 5 MW Average power 10 k. W RF pulse duration 4. 5 μs Gain 54 d. B Efficiency 43 % Maximum input power 200 W Band width 10 MHz Cathode voltage 315 k. V Beam current 335 А Filament heater voltage 30 V Filament current 24 А

Modulator Parameters of К 2 modulator series (Scandi. Nova Systems) Modulator К 2 -3 Parameter Unit K 2 -1 K 2 -2 K 2 -3 Klystron RF Peak Power approx MW 35 40 45 Klystron RF average Power approx k. W 1, 6 modulator Peak Power MW 74, 3 91, 5 100, 5 modulator average Power k. W 4, 3 5, 0 5, 1 Pulse voltage k. V 270 300 314 Pulse current A 275 305 320 Pulse repetition Frequency range Hz 1 -10 Pulse Length (top) ìs 4, 5 4 3, 5 Flatness % ± 1 ± 1 Repeatability % ± 0, 2

Power compression system BINP made SLED type power compression system Main parameters of BINP made power compression system. Cavity diameter D Cavity height 196 мм H Operating frequency 346. 6 мм f 0 Range of mechanical tuning 2856 МHz f f/ H Quality factor Q 0 Unloaded time 0 Loaded time TC = 0/(1+ ) Moment of phase switching 5 МHz 2. 75 МHz/мм 95000 11 μs 3 μs RF pulse duration from the klystron 3. 5 μs Power multiplication coefficient К 0 7. 29

Measured input and reflected power from SLED system cavities

Sub harmonic bunching system Sub-harmonic bunching cavity is used to bunch beam before bunching cavity with main frequency. In our case the frequency of sub-harmonic cavity can be chosen as main frequency divided by 8 (357 MHz) or by 16 (178 MHz). To decrease cavity sizes it can be performed by toroidal form. The loss power of cavity is 2 -5 k. W. The amplifier tube can be used as power source for the cavity. Such power source supplies sub-harmonic cavity with frequency of 178 MHz in preinjector complex VEPP-5 in BINP SB RAS.

RF buncher Electric field in RF buncher along beam axis with storage energy of 1 J RF buncher design Electrodynamics cavity parameters Cavity dimensions Internal cells diamters 2 b 81. 9 mm Unloaded quality factor Iris diameters 2 a 23. 8 mm Shunt impedance Iris thickness t Period D 5 mm 48. 7 mm Coupling factor 3350 0. 389 MOhm 1. 3

RF scheme for the first and second accelerating structures

RF scheme for all accelerating structures except the first and second structures

Attenuator and phase shifter I – double T-bend, II – waveguide with two plungers 1` and 2` v. Wave amplitude depends on the length between plungers and doesn’t depend on common distance v. The phases depend on common distance and don’t depend on the length between plungers

RF scheme of debuncher-monochromatic Basic parameters of the klystron TH 2163 A Parameters of modulators (K 1 series) Operating frequency 2856 MHz Pick output power 10 MW Average power 10 k. W RF pulse duration 3. 5 μs Gain 50 d. B Efficiency 48 % Maximum input power 200 W Band width 10 MHz Cathode voltage 168 k. V Beam current 124 А Filament voltage 15 V Filament current 15 А Modulator of К 1 series (“Scandi. Nova Systems”) Parameter Unit K 1 -1 K 1 -2 K 1 -3 Klystron RF Peak Power approx MW 6 7 10 Klystron RF average Power approx k. W 3, 0 4, 1 6, 4 modulator Peak Power MW 14, 7 17, 8 22, 6 modulator average Power k. W 10 15 20 Pulse voltage k. V 140 155 170 Pulse current A 105 115 133 Pulse repetition Frequency range Hz 30 -300 Max PRF at max Peak & average P Hz 112 148 183 Pulse Length (top) ìs 4, 5 4 3, 5 Flatness % ± 1 ± 1 Repeatability % ± 0, 2