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Induction Synchrotron Experiment in the KEK PS Induction Synchrotron Experiment in the KEK PS Ken Takayama High Energy Accelerator Research Organization (KEK) on behalf of Super-bunch Group which consists of staffs of KEK, TIT, NAT, and Nagaoka Tech. Univ. 25-29 June, 2007 Albuquerque, USA 2007 Particle Accelerator Conference Contents ■Brief history of the Induction Synchrotron R&D at KEK ■Outline of the Induction Synchrotron (IS) ■Experimental results using the KEK 12GeV PS ■Perspective: beyond the POP experiment ■Summary History of Induction Synchrotron Research at KEK Year Major topics & outputs Events 1999 Proposal of the Induction Synchrotron concept by K.Takayama and νFACT’99 J.Kishiro 2000 R&D works on the 1MHz switching power supply started. EPAC2000 2001 R&D works on the 2.5kV, 1MHz induction acceleration cell started. PAC2001 Proposal of a Super-bunch Hadron Collider Snowmass2001 2002 ICFA-HB2002 EPAC2002,RPIA2002 2003 5 years term Project using the KEK-PS officially started with a budget PAC2003 of 5M$. ICFA-HB2003 2004 zThe first engineering model of the switching P.S. was established. APAC2004 3 induction acceleration cells (2 kVx3=6 kV) were installed. (May) EPAC2004 zFirst experimental demonstration of induction acceleration in the KEK- ICFA-HB2004 PS (Oct. - Nov.) CARE HHH2004 zBarrier trapping at the injection energy of 500MeV and a 500 nsec-long bunch was achieved. (Dec.) 2005 Proposal of All-ion Accelerators PAC2005 Another 3 induction acceleration cells (2 kVx3=6kV) were installed (Sept). zQuasi-adiabatic non-focusing transition crossing was demonstrated in the hybrid synchrotron (RF capture + induction acceleration), (Dec.) 2006 Another 4 induction acceleration cells (2 kVx4=8 kV) were installed.(Jan.) RPIA2006, HB2006 zFull demonstration of the IS concept (March) EPAC2006, HIF06 zAll-ion Accelerator was awarded a patent. (November) The first Synchrotron and newest one E=340MeV Week focusing by courtesy of LBNL by courtesy of CERN Large Hadron Collider E=7 TeV Circumference= 27km Beam commissioning in 2007 fall Concept of Induction Synchrotron .Takayama and J.Kishiro, “Induction Synchrotron”, Nucl. Inst. Meth. A451, 304(2000) Principle Image of Accelerator RF Synchrotron RF voltage Super-bunch RF bunch Combined function of Voltage with gradient accel./confinement Induction acceleration cells Pulse voltage for acceleration for confinement Separate function introducing a big freedom of beam handling Induction Synchrotron MHz operation -> serious heat-deposit Difference between RF and Induction Synchrotron seen in Phase-space RF bunch Super-bunch ΔE allowed maximum energy spread Induction Synchrotron RF Synchrotron This space is not available for acceleration. peak density: λ(0) < λlimit Equivalent Circuit for 2.5kV Induction Accelerating System DC P.S. Switching P.S. Transmission line (60m long) Induction Cell V2 V1 R C L (330Ω) (~200pF) (110mH) V0 C0 Z0(125Ω) V3 CT Z(210Ω) (matching resistance) IZ (always monitored) V0 ~ V2 = V3 ~ ZIZ (calibrated) More information on key devices: http://conference.kek.jp/rpia2006/ Switching Power Supply: switching sequence, output pulse Switching arm S3 (7 MOSFETs in series) S1 1) S3 V Gate pulse dI/dt=0 2) S2 S4 MOSFET board 2.5kV, 20A, 1MHz, 500nsec Gate drive power drive IC MOSFET 1) (rear side) (rear side) 2) Gate trigger water signal(light) Heat sink for MOSFET & drive IC M.Wake et al. MOPAN042 Scenario of the POP Experiment The scenario has been divided into three steps. RF voltage 1 st Step: RF trapping + induction accel. (Hybrid Synchrotron) 500 MeV -> 8 GeV for 6x1011ppb 2004/10-2005/3 Induction voltage 2nd Step: Barrier trapping by induction step-voltages at 500 MeV through 2005 3rd Step: Barrier trapping + induction accel. (Induction Synchrotron) 500 MeV -> 6 GeV for 2-3x1011ppb 2006/1-3 Monitored signals of induction voltage and an RF bunch signal in the step 1 experiment 1.6 kV/cell 1 (8Gev)-1.5(500MeV) msec z Synchronization between two signals has been confirmed through an entire acceleration. Step 1 Hybrid Synchrotron Proof of the induction acceleration in the Hybrid Synchrotron: Position of the bunch centroid in the RF phase Vrfsinφ ~ φs 0 π-12.40 +Vind(5.6 kV) 12.4 -V ind π-5.70 no Vind 5.70 φ 0 -10 π+1 0 φs π TC before Transition after transition 6x1011ppb Voltage received by the bunch center V=Vrf・sinφs + Vind 500 MeV 8 GeV RF Induction K.Takayama et al., Phys. Rev. Lett. 94, 144801 (2005). Step 1 Hybrid Synchrotron Focusing-free Transition Crossing (FFTC) in the Hybrid Synchrotron RF Synchrotron Hybrid Synchrotron zRF voltage: always on around γT zRF voltage: off around Transition energy. Δp/p zInduction voltage: continuously triggered γ < γ for acceleration. T Specific features in TC: Δp/p φ zNon-adiabatic motion zSync. motion frozen γ < γT φ φ stretched in Δp/p compressed in phase Δp/p goes to zero drift γ ∼ γT reach momentum aperture φ Jonsen effects: serious γ ∼ γT φn+1=φn+2πη(Δp/p)n+1 Opposite drift φ 2 +k (Δp/p) n+1 Instabilities: φ Microwave instability @ (KEK-PS) γ > γT e-p instability (RHIC) φ γ > γT φ Simulation Results Experimental Results for QNTC Polynomial reduction NTC QNTC Vp (exp) n Vrf ()t = at sin[ω rf t] kinetic energy (GeV) 12 456400 for t = 0.125 10 0 300 Vp (kV) 8 200 6 100 4 0 RMS bunch length (nsec) 0.4 0.6 0.8 time from P2 (sec) Bunch length measured by Wall Current Monitor. Transition energy (b) Y.Shimosaki, K.Takayama, and K.Torikai,Beam Intensity measured by Slow Intensity Monitor Phys. Rev. Lett. 96, 134801 (2006). (2x1011ppb/div) and Wall current measured by Wall Current Monitor(a) NTC and (b) QNTC. Step 2: Confinement by t=0 msec after injection Induction Step-barriers Formation of a 600nsec-long bunch injected 6 kV barrier-voltage proton bunch 100nsec t=100msec after injection Shallow notch potential 600nsec trapped protons K.Torikai et al., KEK Preprint 2005-80 (2005), submitted to Phys. Rev. ST-AB Step 3-1 Accelerator parameters & control system Cross-section Induction of vacuum pipe Synchrotron Δp/p>0 KEK-PS Induction Cell Induction Cell for Acceleration C0 339 m for Confinement Inj/Ext Energy 0.5/6 GeV Revolu fre. 667- 876 kHz Accel. time period 2.0 sec ΔR Monitor dB/dt 0.377 T/sec Proton Beam Induction acceleration voltage: Bunch Monitor acceleration 6.4 kV (4 sets) confinemet 10.8 kV (6 sets) P2 Trigger Delay Transmission line Transmission line Switching Pattern DSP DSP Pattern Switching Power Supply Controller 1 (720MHz) (1GHz) Controller 2 Power Supply 2.0 sec P2 : timing of acceleration start B(t) DSP : logical processing of the input signals (digital signal processor) (delay in master signal, on/off decision) Pattern Controller : generation of the gate trigger pattern Transient region t T.Iwashita et al., TUPAN044 in this PAC Step 3-2 P2 (just start of accel.) P2+400 msec near end of accel. (6GeV) Induction Synchrotron Movie show of the full demonstration Injection Start of acceleration (500MeV) End of acceleration (6GeV) beam position (10 mm/div) Beam current (1012/div) acceleration voltage pulse (1kV/div) bunch signal K.Takayama et al., “Experimental Demonstration of the Induction Synchrotron”, Phys. Rev. Lett. 98, 054801 (2007) Step 3-3 Temporal Evolution of the Bunch Length: Induction Adiabatic dumping in the Induction Synchrotron Synchrotron Barrier voltage 200 150 Δt 100 Ana Expt-1 Full bunch width in ns Expt-2 50 Expt-3 Expt-4 Level of the usual RF acceleration 0 0.5 1.0 1.5 2.0 Time in sec Theory: A WKB-like solution of the amplitude-dependent oscillation system (synchrotron oscillation in the barrier bucket) T. Dixit et al., “Adiabatic Dumping of the Bunch-length in the Induction Synchrotron”, published in N.I.M. (2007). Poster FRPMN033 in this conference Technical Issues and further R&D Works Noise Problems (TUPAN050) Essentially pulse devices with reflection -> potential noise sources -> pulse leak currents through the earth or EM waves propagate in air -> shielding or protection by optimized cabling Importance of Trigger Control and Beam Physics Issues Bunch signal How to get the macroscopic center of bunch correctly Threshold -> incorrect gate timing line • -> acceleration or deceleration by the barrier voltage ■ Over-focusing and defocusing due to the droop voltage ■ Chaotic diffusion caused by the discrete barrier voltages t ■ beam loss due to adiabatic motion of barrier voltage-pulses error Next Generation of Switching Power Supply (MOPAN042) Requirement of high intensity beam acceleration -> beam loading effects -> low impedance acceleration cell at 1 MHz -> high driving current keeping the same accelerating voltage -> large switching arm current -> novel solid-state switching elements, such as SIThy or SiC from the Induction Synchrotron to All-ion Accelerators from the experimental demonstration of induction acceleration in the KEK-PS zStable performance of the switching power supply from ~0Hz to 1MHz zMaster trigger signal for the switching P.S. can be generated from a circulating beam signal Allow to accelerate even quite slow particles Betatron motion doesn’t depend on ion mass and charge state, once the magnetic guide fields are fixed. A single circular strong-focusing machine can accelerate from proton to uranium. almost injector-free All-ion accelerators for a low intensity beam K.Takayama, K.Torikai, Y.Shimosaki, and Y.Arakida, “All Ion Accelerators”, (Patent 3896420, PCT/JP2006/308502), and J. of Appl. Phys. 101, 063304 (2007) All-ion Accelerator (Injector-free synchrotron) & its Applications Gate trigger ctr. B. Material Science and selective breeding: Switching Irradiation on bulk materials power supply Bulk Ion bunch ion-sourc High-voltage target or High-energy Plant seeds Bunch ions (mutation) monitor Induction cells B-1 Implant B-2 Electro-excitation ions ions extarction e target target Energy dumper A.
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