Pulsed Ion Linac for EIC January 27, 2010 Go to "View | Header and Footer" to add your organization, sponsor, meeting name here; then, click "Apply to All"
Content Pulsed linac Short Normal Conducting section: RFQ and IH structure Stripper for heavy ions at 12 MeV/u
Basic parameters of the linac Linac layout Ion Sources RFQ IH QWR QWR HWR DSR MEBT Stripper Normal conducting Superconducting
Radio Frequency Quadrupole A Segment of the RFQ Basic RFQ Parameters Frequency 115 MHz Total length 3.6 m Voltage 85 kV Average radius 7 mm Number of segments 4 Input energy 25 KeV Output energy 500 keV/u
Example of a short MEBT Q1 Buncher Q2 Q3 Q4 L= 995 mm Basic Quadrupoles Parameters Basic Buncher Parameters Eff. Length (mm) Gradient (T/m) Q1 20.0 23.0 Q2 50.0 -22.0 Q3 32.75 Q4 -16.5 Cavity Quarter Wave Voltage 0.8 MV Frequency 117.3 MHz Length 340 mm
Normal Conducting IH cavities TRIUMF Separated DTL Courtesy Bob Laxdal
Normal Conducting IH structure U. Ratzinger (Frankfurt) Group has built it for the BNL EBIS injector project
Stripping energy Lead ions
Superconducting cavities QWR HWR DSR 119 cavities 21 cryostats
Voltage gain per cavity for lead ions
Voltage gain per cavity for protons
Energies of different ion beams
Accelerated Beam Parameters Transverse normalized emittance (5rms) ~ 1 mmmrad Longitudinal emittance (5rms) <10 keV/unsec Momentum spread can be controlled by the rebuncher and can be as low as ~0.05%.
Proton Beam Linac Pulse Length (s) = 2.50E-04 Frequency (MHz) = 115 Number of Bunches in Pulse= 28750 Average current per pulse, P (A)= 2.00E-03 Charge per pulse (C)= 5.00E-07 Number of protons per pulse = 3.13E+12 Injection Efficiency= 0.9 Transverse cooling time (s) = 0.130 Longitudinal cooling time (s) = 0.067 RF acceleration time (s) = 0.080 Injection Extraction Cycle Time(s) Ion A Q I (A) S (m) MeV/n γ β N_total Pulses P 1 300 200 1.21 0.57 1.10E+13 3000 4.22 0.97 6.43E+12 4 0.70 250 9.17E+12 5.36E+12 3 0.61 7.34E+12 4.29E+12 0.52 150 5.50E+12 3.22E+12 2 0.43
Lead Beam Linac Pulse Length (s) = 2.50E-04 Frequency (MHz) = 115 Number of Bunches in Pulse= 28750 Average current per pulse, Pb (A)= 5.00E-04 Charge per pulse (C)= 1.25E-07 Average charge state of lead ion= 67 Number of lead ions per pulse = 1.17E+10 Injection Efficiency= 0.5 Transverse cooling time (s) = 0.130 Longitudinal cooling time (s) = 0.067 RF acceleration time (s) = 0.080 Injection Extraction Cycle Time(s) Ion A Q I (A) S (m) MeV/n γ β N_total Pulses Pb 207 1 300 70 1.08 0.37 2.54E+11 1180 2.27 0.90 1.04E+11 18 2.48 250 2.12E+11 8.66E+10 15 2.10 200 1.69E+11 6.93E+10 12 1.71 150 1.27E+11 5.20E+10 9 1.32
Spin tracking in the LINAC (first segment of the linac) Linac with solenoids Linac with doublets Initial Polarization Direction Final Polarization in Linac with Solenoids (Direction of polarization changes) Final Polarization in Linac with Doublets (Direction remains same as initial) Emittance 5*Emittance (%) Spread X 99 3x10-2 98 2x10-1 1x10-2 5x10-2 Y 3 x10-2 Z 4x10-2 96 3x10-1 7x10-2
QWR and HWR production at ANL QWR, f=109 MHz, =0.15 HWR, f=172 MHz, =0.26
Advanced EM Optimization of New Cavities Advanced EM optimization : outer conductor: form cylinder to conical shape Drift tubes are highly optimized to reduce EPEAK 2.5 deg drift tube face tilt to compensate beam steering effect 109 MHz Frequency 109.125 72.75 MHz beta 0.14 0.077 U0 at 1 MV/m 0.4 0.39 J bl 39 32 cm EPEAK at 1 MV/m 5.0 4.6 MV/m BPEAK at 1 MV/m 92 76 Gs G 40 26 Ohm Rsh/Q 548 575 Voltage per cavity 2.1 2.5 MV Dynamic LHe load 6 11.4 W 72.75 MHz
Cryomodule assembly at ANL beam
Cavity subsystems Piezoelectric tuner (PZT) 4 kW capacitive coupler ~90 Hz window 35 m displacement 4 kW capacitive coupler Adjustable 1 cold and 1 warm windows Pneumatic slow tuner beam PZT has been tested with excellent performance RF Coupler
Recently developed and built QWR, 72.75 MHz
Remaining tasks for the linac pre-conceptual design Status of the injectors 2 mA is available for polarized light ion beams 2 mA is not available yet for lead ions ~0.5 mA is realistic number Can be increased by using 56 GHz ECRs –expensive device Update the linac design on the base of recent (3-4 years) progress in performance of TEM class cavities Introduce better optimization of EM parameters to reduce Epeak/Eacc and Bpeak/Eacc Peak magnetic field can be as high as ~90 mT for the pulsed operation Peak electric field ~40 MV/m Optimal injection energy to the pre-booster Do we need 100 MeV/u lead ions and 280 MeV H-minus? Focusing system In SC environment, focusing by SC solenoids is cost effective Spin dynamics studies to avoid depolarization effects: compare quadrupole and solenoid focusing