RAON LEBT Design Yonghwan Kim Institute for Basic Science Yonghwan Kim Institute for Basic Science

RISP LEBT Layout ECRIS 1 ESQ doublet BM1 Triplet slit BM2 TripletPair solenoid Pair solenoid Pair solenoid chopper MHBVE Solenoid RFQ ECRIS 2 MEBT

LEBT Beam pipe radius Beam Pipe Inner Radius = 1.5 × Maximum Beam Size ( 4.0 × rms Beam Size ) Center of the U single particle dcdc dhdh dvdv Max [1.5×d v, 1.5×d h +d c ]

LEBT Beam pipe radius component rms beam radius offset between beam center and beam pipe center Max beam enveloprequired beam pipe inner radius final dicision xyxyxyxyNote Pair solenoid circular 4.5 circular ESQ(doublet) circular Bending Magnet 01 [90degree, rho 600mm] (good field) × 3.5 rectangular4.5 circular ESQ circular Diagnostics circular ESQ circular Bending Magnet (good field) × 4.5 rectangular4.5 circular ESQ circular 4.5 circular D circular Pair solenoid circular Diagnostics circular Collimator circular Diagnostics circular Pair solenoid circular Diagnostics circular Multi harmonic Buncher circular4.5 circular flange Solenoid circular4.5 circular Velocity Equalizer circular4.5 circular flange Categorize in two groups: 1 st with ID = 90mm 2 nd with ID = 140mm

Pair Solenoid right after Ion Source Parametersvalue Center field5,000 Gauss Effective length300 mm Bore diameter170 mm Model & dimension Bore diameter : 170 mm Yoke thickness : 30 mm  B-field in return yoke is about 8000 Gauss Total length : 740 mm Effective length : 300 mm

Pair Solenoid after Ion Source Power consumption Saturation review Total current for the designed field : 131,300 A-turns Power consumption turn number =364turns current =360A Coil inner radius8.5cm coil outer radius24cm total conductor length = [cm] conductor x-sectional area0.8cm2 resistance = Power comsumption = kW Power consumption of the Pair solenoid = kW/coil * 2 coil = 20.5 kW Total current [A-turn] Max. field

ESQ Triplet Pole shape design with 2D design - Bore Radius : 70mm - Circular shaped pole Rule of thumb : circular pole radius = bore radius * 1.15 Multi-pole field strength Normalized to quadrupole [%] Pole tip radius [cm]

ESQ Triplet Effective length : ESQ_1 153mm ESQ_2 150mm ESQ_3 150mm 3D design Alignment tolerance : achieved from the precise machining High voltage : through push-on connector

ESQ Douplet Simple modification of the ESQ triplet -Bore radius : 70mm -Effective length : 150mm

Bending Magnet – C magnet Parametersvalue Beam pipe ID 90 mm  Pole gap : 100mm Bending radius650 mm Bore field1560 Gauss [Note] Pole width = 1.6 * pole gap 2D Design Multi-pole in 2D analysis

Bending Magnet – C magnet  Return yoke width determination : return yoke width 50mm Back leg width [mm] Back leg Field [Gauss] 3D geometry Effective length : 874.9mm

Pair solenoid #2,3,4  Beam Pipe inner radius 45mm  Solenoid bore radius 50mm Coil Power consumption  Coil total length is 85 * 350 = cm / coil  Total resistance is ohm / coil  Total power consumption is 7.52 kW/coil * 2 = kW Return yoke thickness about mm Effective length L_eff = 295 mm

Chopper Electrostatic deflector with commercial high voltage fast switch Coolant in Coolant out Slit & chopped beam dump deflector Case 1. with CopperCase 2. with Stainless steel Thermal analysis for beam dump Convection coefficient : 12,000 W/m2 Beam power : 24W Beam diameter : 10mm

Chopper Consideration on the uncut beam Parameterunitvalue Electrode gap distancemm50 Length of the deflection electrodemm200 Width of the deflection electrodemm60 deflection voltagekV6.4 = (+3.2)-(-3.2) traveling time for the electrodesus Max. dump radial positionmm45 collimation hole radiusmm20 Drift distance between electrodes and collimator mm263 capacitance of the electrodeF1.594e-12

Pulse operation through pulse extraction Accelerating column High voltage side Ground side 30kV Gyrotron klystron High voltage DC power supply DC power supply Pulse switch High voltage DC power supply Isolation Transformer Isolation Transformer

Preliminary design of MHB Analysis model : modified QWR  Do not consider the lumped element matching Field profile Parameter Value Analysis result Stored Energy = 1J converted result operating condition Resonance frequency mode MHz mode MHz mode MHz Q mode mode mode Max E-field at center line mode MV/m kV/m mode MV/m57.5 kV/m mode MV/m18.8 kV/m Max E-field on the cavity surface mode MV/m760.2 kV/m mode MV/m263.6 kV/m mode MV/m109 kV/m Power loss mode kW268 W mode kW26 W mode kW9.4 W

Preliminary design of MHB Major tuning scheme : varying the cavity length through change the RF contact position mode MHz-21.4 kHz/mm mode MHz-82.5 kHz/mm mode MHz-63.1 kHz/mm Minor tuning scheme : using slug tuner & coolant temperature

Preliminary design of Velocity Equalizer Analysis model : QWRField Profile Parameter Value Analysis result Stored Energy = 1J converted result operating condition Resonance frequency MHz Q1149 Max E-field at center line 7.26 MV/m190 kV/m Max E-field on the cavity surface 53.3 MV/m1.395 MV/m Kilpatric factor0.17 Power loss439.2 kW300 W Specifications of the cavity

Preliminary design of Velocity Equalizer Major tuning scheme : cavity length modification -22kHz/mm Minor tuning scheme : slug tuner Tuner diameter25 mm Tuner length5 mm Tuning sensitivity10kHz/mm

Vacuum system Vacuum requirements * Vacuum systemNote LEBT1 × Torr 4 × TMP (500LPS) 2 × TMP (500LPS) -1 pumping station per 4m -Independent pumping for MHB and VE cavity * Benchmark FRIB design standard * Not calculate the beam loss and radiation LEBT beam line 16m Parametervalue Beam pipe inner diameter90 mm Beam pipe total length16 m Beam pipe materialSTS304 outgassing rate after 10h evacuation1× torr L/s /cm2 Distance between vacuum pump4 m Pump inlet pressure1×10 -8 torr Max pressure in the beam pipe1.65×10 -8

Total power consumption of LEBT ComponentPower [kW]Note Pair solenoid 120 Bending Magnet 11.1 Bending Magnet 21.5 Pair solenoid 2, 3, 43 × 15 = 45 MHV1 Solenoid18 VE1 Vacuum3 etc5Cooling water and others TotalAbout 100

Summary Engineering design for each LEBT component was done. It satisfies the requirements from the beam physics design Detailed design for MHB cavity and VE cavity is on-going 1 st pair solenoid, ESQ doublet, and 1 st Bending magnet will be fabricated and installed with the ECRIS, coincidentally