Proton LINAC for the Frankfurt Neutron Source FRANZ

Transcription

1 Proton LINAC for the Frankfurt Neutron Source FRANZ - IAEA - International Topical Meeting on Nuclear Research Applications and Utilization of Accelerators Oliver Meusel 4-8 May 2009 Vienna, Austria

2 Motivation Frankfurt Neutron Source at the Stern - Gerlach- Zentrum 7 Li target development of new accelerator concepts for intense proton and ion beams p + beam collimated n 0 beam nuclear astro physics, measurement of neutron capture cross sections development of high power targets

3 Experimental Setup Scheme of the neutron source 150 kv Terminal W b = 120 kev 4 P = 2.4 x 10 W b W b = 0.7 MeV 3 P b,max = 7 x 10 W W b = MeV 4 P b,max = 2.1 x 10 W Rebuncher Beam Dump Detector Development high n - flux (dc) 7 Li Target Volume Type Ion Source Chopper t = ns f = 250kHz Steerer IH Chopper f = 250 khz Dipole Magnet Bunch Compressor 7 Li Target dc extraction & transport cw operation I b ~ 30 ma pulsed operation, rep. rate 250 khz, τ = 1ns I b ~ 2 ma activation mode compressor mode

4 Compressor Mode Primary beam properties and resuling neutron flux low energy proton beam Beam energy: 120 kev Beam current: 200 ma Pulse width: ns Proton beam at the target Final energy (adjustable): MeV Repetition rate: khz Pulse width : 1 ns Neutron production Li( p, n) 7 7 Be target and detector with kindly support by FZK and GSI. Neutron beam Energy: kev Production rate: n / pulse 5 10 n / s Neutron flux at the target: n / pulse 3 10 n / s 1 10 n / cm s

5 Ion Source Volume type ion source with hot filament driven gas discharge K. Volk, R. Nörenberg Operation mode dc Ion species / fraction Protons / 90 % Discharge power kw Extraction current 200 ma Extraction voltage 62 kv Extraction field strength 5 kv/mm Beam energy 120 kev Input emittance (norm. rms) 0.07 π mm mrad Aspect ratio 0.2 Cross-sectional view of the ion source

6 Ion Source Ion beam extraction v = 2eU m p simulated beam extraction using a pentode system extracted beam current with 3% noice (simulated) n p = I 1 A I I K = peak η = 3/ 2 2πe v r 4 πε 0 2q U I0 b proton density n p = m -3 gen. Perveance K = compression ratio η = 1,

7 Low Energy Beam Transport Solenoidal transport section to provide space charge compensation d d z 2 2 r S ε K = 3 + r r S 2 S κ ( z ) r S KV - envelope equation aperture 100 mm, B z = 0,6 T scheme of LEBT section

8 Chopper Chopper for macro pulse generation C. Wiesner, H. Dinter macro pulse current distribution (simulated) scheme of the chopper system compression ratio η = 1 gen. Perveance K = n p = m -3

9 Accelerator Radio Frequency Quadrupol - RFQ A. Schempp / NTG company RFQ test module RFQ technical design

10 Accelerator Focussing, Compression and Acceleration Operating frequency Ion species Length of RFQ Length of IH-DTL Tank diameter IH 175 MHz Protons 1.7 m 0.6 m 510 mm proton source # of RFQ cells 97 # of IH gaps 8 Input energy 120 kev Input emittance (norm. rms) 0.56 π mm mrad Electrode voltage (RFQ) 75 kv LEBT RFQ A. Bechtold Max. gap Voltage IH-DTL Exp. Power consumption RFQ Exp. Power consumption IH Current Output eenergy RFQ 300 kv 150 kw 45 kw max. 200 ma 700 kev Output ebergy IH 2 MeV Coupling factor 0.03

11 Accelerator IH-DTL and CH-Rebuncher final energy 2 MeV U. Ratzinger, M. Heilmann energy variation ± 0.2 MeV H. Podlech, A. Metz 8 gap and internal msq triplet output beam enrgy 2MeV CH type cavity 4gap

12 Accelerator Properties of a single micro bunch downstream of the accelerator RFQ-IH E p = 2 MeV CH E p = ± 0.2 MeV microbunch current distribution (simulated) compression ratio η = 6 gen. Perveance K = n p = m -3

13 Bunch Compressor Layout based on Mobley - typ bunch compressor L.P. Chau, D. Noll compressed micro bunch current distribution (simulated) compression ratio η = 48 gen. Perveance K = scheme of the bunch compressor n p = m -3

14 Intensity Target Development of high power target at FZ Karlsruhe and KALLAS - Laboratory D. Petrich, F. Käppeler r = 10 mm y profile x / mm transverse beam profile (simulated) target prototype for beam power up to 6 kw avg. power ~ 4 kw peak power ~ 20 MW

15 4π πbaf2 Detector Array high granularity (#43) to reduce count rate per module fast timing (600 ps) to achieve acceptable TOF resolution good energy resolution low neutron sensitivity

16 Systems Perspective source is constructed LEBT vacuum tests RFQ test module First Beam 2010 compressor design high power target test detector reassembled

17 Thank you for your attention. on behalf of: A. Bechtold, L.P. Chau, M. Heilmann H. Podlech, U. Ratzinger, A. Schempp, C. Wiesner, S. Schmidt, K. Volk / IAP, Goethe University Frankfurt M. Heil, R. Plag, R. Reifarth / GSI, Darmstadt K. Stiebing, J. Stroth / IKF, Goethe University Frankfurt F. Käppeler, D. Petrich / IKF, FZ Karlsruhe acknowledgment: LINAC-AG AG-Schempp NNP-AG FZK / GSI / IAEA