RF scheme of electron linear accelerator with energy MeV Levichev A.E. Budker Institute of Nuclear Physics SB RAS

Introduction

Debuncher-monohramator

Accelerating structure 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.

Operating frequency f МHz Operating mode  Unloaded quality factor Q  10 4 Group velocity V gr  C Shunt impedance R sh 51 МОhм/м Unloaded time  0 = 2  Q 0 /  1.47 μs Attenuation parameter  = 1/(  0  V gr ) /м Integrated attenuation parameter  L Filling time T f =L/ V gr μs Period34.98 мм Inner diameter of the cell cavity83.8 мм Iris aperture diameter25.9 мм Iris thickness6 мм Overvoltage coefficient1.7 Basic parameters of BINP made accelerating structures

RF power source Picture of TH 2100 klystrons series. Operating frequency2856 MHz Peak output power45.5 MW Average power10 kW RF pulse duration4.5 μs Gain54 dB Efficiency43 % Maximum input power200 W Band width10 MHz Cathode voltage315 kV Beam current335 А Filament heater voltage30 V Filament current24 А Basic parameters of TH 2128 C/D klystron.

Modulator ParameterUnitK2-1K2-2K2-3 Klystron RF Peak Power approxMW Klystron RF average Power approxkW1,6 modulator Peak PowerMW74,391,5100,5 modulator average PowerkW4,35,05,1 Pulse voltagekV Pulse currentA Pulse repetition Frequency rangeHz1-10 Pulse Length (top)ìs4,543,5 Flatness%± 1 Repeatability%± 0,2 Parameters of К2 modulator series (ScandiNova Systems) Modulator К2-3

Power compression system Cavity diameter D196 мм Cavity height H346.6 мм Operating frequency f МHz Range of mechanical tuning  f  5 МHz  f/  H 2.75 МHz/мм Quality factor Q Unloaded time  0 11 μs Loaded time T C =  0 /(1+  ) 1 μs Moment of phase switching 3 μs RF pulse duration from the klystron 3.5 μs Power multiplication coefficient К Main parameters of BINP made power compression system. BINP made SLED type power compression system

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 kW. 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 Internal cells diamters 2b81.9 mm Iris diameters 2a23.8 mm Iris thickness t5 mm Period D48.7 mm Unloaded quality factor3350 Shunt impedance0.389 MOhm Coupling factor1.3 Cavity dimensions Electrodynamics cavity parameters Electric field in RF buncher along beam axis with storage energy of 1 J RF buncher design

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`  Wave amplitude depends on the length between plungers and doesn’t depend on common distance  The phases depend on common distance and don’t depend on the length between plungers

RF scheme of debuncher-monochromatic Operating frequency2856 MHz Pick output power10 MW Average power10 kW RF pulse duration3.5 μs Gain50 dB Efficiency48 % Maximum input power200 W Band width10 MHz Cathode voltage168 kV Beam current124 А Filament voltage15 V Filament current15 А ParameterUnitK1-1K1-2K1-3 Klystron RF Peak Power approx MW6710 Klystron RF average Power approx kW3,04,16,4 modulator Peak Power MW14,717,822,6 modulator average Power kW Pulse voltagekV Pulse currentA Pulse repetition Frequency range Hz Max PRF at max Peak & average P Hz Pulse Length (top)ìs4,543,5 Flatness%± 1 Repeatability%± 0,2 Basic parameters of the klystron TH 2163 A Parameters of modulators (K1 series) Modulator of К1 series (“ScandiNova Systems”)