Beam Dynamics and Emittance Growth

Transcription

1 2010/03/09 Beam Dynamics and Emittance Growth Christoph Wiesner

2 1. Solenoidal Focusing and Emittance Growth 2. Beam Deflection and Emittance Growth 3. Time-dependent Kicker Fields, Electron Effects and Emittance Growth 4. Beam Dynamics in the ExB Chopper System 5. Conclusion & Outlook

3 Low Energy Beam Transport (LEBT) Section dc extraction & transport W b,max = 120 kev I b,max = 200 ma pulsed beam operation τ pulse = 100 ns rep. rate = 250 khz Solenoid Typ I: Aperture 100 mm, B z = 0.78 T, length 251 mm Solenoid Typ II: Aperture 150 mm, B z = 0.66 T, length 408 mm

4 Field Distribution Field Calculations using CST EMS.

5 Emittance Growth and Filling Degree B max = 314 mt

6 Beam Transport through LEBT Section ε ε out rms,norm in rms,norm = 1.6 Thanks to Y.Nie B 0 = 314 mt B 0 = 345 mt B 0 = 515 mt B 0 = 624 mt

7 Beam Deflection with Electric Kicker

8 Beam Deflection with Electric Kicker

9 Proton Pulse: Current and Emittances Input Emittance: ε x rms, norm = ε y rms, norm = 0.23 π mm mrad I / ma Output Emittance (no e - ): Pulse Plateau: ε x rms, norm = 0.50 π mm mrad ε y rms, norm = 0.33 π mm mrad Output Emittance (with e - ): Pulse Plateau: ε x rms, norm = 0.38 π mm mrad ε y rms, norm = 0.46 π mm mrad t / µs Electric Kicker

10 Beam Deflection with Magnetic Kicker

11 Proton Pulse: Current and Emittances Input Emittance: ε x rms, norm = ε y rms, norm = 0.23 π mm mrad Output Emittance (no e - ): Pulse Plateau: ε x rms, norm = 0.73 π mm mrad ε y rms, norm = 0.37 π mm mrad Output Emittance (with e - ): Pulse Plateau: ε x rms, norm = 0.66 π mm mrad ε y rms, norm = 0.54 π mm mrad Magnetic Kicker

12 Output Distributions Magnetic Kicker Simulation without Electrons. Simulation with Electrons.

13 Electron Effects in Time-dependent Kicker Fields Without Consideration of Electrons.

14 Electron Effects in Time-dependent Kicker Fields With Consideration of Electrons.

15 ExB Chopper System Riezlern, 09/03/2010 Chopping of High Intensity Beams: Avoiding long drifts due to high space charge. Minimizing duty factor for electrostatic beam deflection in order to reduce risk of voltage breakdowns. Beam dumping outside transport line preferable in order to avoid high power deposition and uncontrolled production of secondary particles.

16 ExB Chopper System Riezlern, 09/03/2010

17 ExB Chopper System Riezlern, 09/03/2010 Deflector & HV Pulse Generator

18 ExB Chopper System Riezlern, 09/03/2010 Static Magnetic Deflection Dumped Beam DC Beam Deflector & HV Pulse Generator V defl = 0 kv

19 ExB Chopper System Static Magnetic Deflection compensated by Pulsed Electric Deflection during 100ns Pulse. Riezlern, 09/03/2010 Pulsed Beam DC Beam Deflector & HV Pulse Generator V defl = 10.5 kv

20 ExB Chopper Measured Voltage Pulse Simulated Proton Pulse B Chopper = 58 mt B Septum = 300 mt

21 ExB Chopper System Riezlern, 09/03/2010 Sol2 Septum Magnet Chopper Magnet Sol3

22 ExB Chopper System Riezlern, 09/03/2010 Sol2 Septum Shielding Tube Chopper Magnet Sol3 Deflector Plates

23 ExB Chopper System Riezlern, 09/03/2010 Sol2 Septum Shielding Tube Chopper Magnet Sol3 Deflector Plates

24 Conclusion & Outlook Aberration induced emittance growth must be carefully examined. Nonlinear fields are limiting filling degree of solenoidal lenses. Time-dependent beam deflection increases emittance in deflection plane. Electron effects can significantly influence beam radius and emittance growth. Collective effects of beam ions, compensation and secondary electrons must be considered. Multi-species PIC codes for simulation of time-dependent kicker fields are ready. Deflection test stand for experimental investigations is ready.

25 Thank you for your attention

26 Low Energy Beam Transport (LEBT) Section dc extraction & transport W b,max = 120 kev I b,max = 200 ma pulsed beam operation τ pulse = 100 ns rep. rate = 250 khz

27 Solenoid Lenses Type I Length: 251 mm Aperture: 100 mm B max : 0.78T Type II Length: 408 mm Aperture: 150 mm B max : 0.66T

28 Emittance Growth Riezlern, 09/03/2010

29 Calculated B-Field EMS-Sim B-Field

30 Filling Degree (b) (e) (g)

31 Filling Degree Typ II Riezlern, 09/03/2010

32 Beam Transport Riezlern, 09/03/2010

33 Proton Pulse Current (Electric Kicker) Input Emittance: ε x rms, norm = ε y rms, norm = 0.23 π mm mrad Output Emittance (no e - ): Pulse Plateau: ε x rms, norm =0.50 π mm mrad ε y rms, norm =0.33 π mm mrad Total Pulse: ε x rms, norm = 1.52 π mm mrad ε y rms, norm = 0.32 π mm mrad Output Emittance (with e - ): Pulse Plateau: ε x rms, norm =0.38 π mm mrad ε y rms, norm =0.46 π mm mrad Total Pulse: ε x rms, norm = 1.28 π mm mrad ε y rms, norm = 0.46 π mm mrad

34 Output Distributions Electric Kicker Simulation without Electrons. Simulation with Electrons.

35 Electric Kicker (no electrons) Riezlern, 09/03/2010 Electric Kicker (with electrons)

36 Separation Tank Riezlern, 09/03/2010 Sol2 Chopper Magnet Septum Magnet Sol3 Beam Repeller Electrodes Halfpipe Shielding Tube

37 Separation Tank Riezlern, 09/03/2010 Sol2 Chopper Magnet Septum Magnet Sol3 Deflector Plates Beam Repeller Electrodes Halfpipe Shielding Tube

38 Field Simulation of All Magnetic Components Sol2 Chopper Magnet Septum Magnet Sol3 Beam

39 Field Simulation of All Magnetic Components Sol2 Chopper Magnet Septum Magnet Sol3 Beam Halfpipe Shielding Tube

40 Proton Pulse Riezlern, 09/03/2010