Transcript Document
“Electron cooling device in the project NESR (FAIR)" V.B. Reva Budker Institute of Nuclear Physics, Novosibirsk, Russia Moscow, 18-20 June, 2008 List of the electron cooling devices manufactured from 1988: LEAR, IUCF, TSR, CELSIUS, TARN-II, ESR, CRYRING, ASTRID, COSY, USA (FNAL), + BINP – Germany SIS (1998), China (CSRm, CSRe), Switzerland CERN The possibility to storage and many-hours traps of the charge ions in the different charge state enables to produce a many interesting experiments in the nucleus and atomic physics. The New Experimental Storage Ring NESR with its instrumentation for atomic physics experiments 1. Electron cooler 2. Electron target The NESR will be filled with energetic highly-charged heavy ions and with exotic nuclei. At the gas jet target ion-atom reactions as well as the structure of ionized atoms will be studied; x-ray spectroscopy, zero-degree electron spectroscopy, recoilion-momentum spectroscopy, and laser spectroscopy will be available. At the electron target the atomic assisted electronelectron interaction will be studied; here also laser techniques and x-ray spectroscopy will support the experiments.. Moreover, the highly-charged heavy ions can be decelerated in the NESR down to the MeV/u region and extracted toward a fixed target area. There, atomic reactions with highlycharged ions at low velocities will be performed; x-ray spectroscopic and laser techniques will be applied. Scheme of the electron cooling The energy transfer from the hot ions to the cold electrons electrons Joint motion of the electrons and ions ions Cooling section Start point of the interaction Final point of the ineraction Strong magnetized Coulomb interaction – collision types moving of force line of the magnetic field Larmour motion transverse temperature of the electron gas is not important for cooling fast ion adiabatic curve of the magnetic force line produces additional “temperature” of electron gas magnetized 4ne e 4 LC F me free Coulomb collision multiply collisions v ve , strong magnetization v ve , v 4ne e 4 LC v F , me v 2 ve2|| ve 4ne e 4 LC v F . 3 2 me v 2 ve2|| e2 V 2 mve H , 3 ve V H L L V 1 pe Density of proton beam versus beam radius during cooling process 1000 Illustration of the ion beam cooling 100 10 -1 -2 0 1 2 t=0 time -2 -1 0 r, cm 1 2 Cooling process in LEIR (LHC) Signal from ion beam profile monitor Injection and cooling Injection and cooling General view of EC500 NESR cooler Main parameters of the electron cooler for NESR Energy of the reference ion (A/Z248/922.7) Maximum electron energy Electron current Diameter of the electron beam in the cooling section 740 MeV/u. 450 kV 2A 0.5-2 cm Magnetic field in the cooling section, G 2000 Gun solenoid field, G 4000 Maximum accelerating voltage 500 kV Ramping of the electron energy (400 kV – 2kV) less 1 s Number of dinametron section 25 Voltage per dinametron section 20 kV SF6 pressure 1.7 Length of cooler section, cm 500 Residual pressure in the cooling section Fraction of the orbit 10-10 – 10-11 torr 0.023 Basic features of coolers produced by BINP 1. Tunable of the coils position for generation precise magnet field at cooling section with straightens about 10-5 Compass like system for measuring of the transverse component of the magnetic field 1 2 4 2 I 3 II IV Laser Electronic unit Preamplifier Y Preamplifier пре д пре д- Modulation Integrator Synchr. detector Integrator Synchr. detector Array X III Current sensors Diagram of the measuring device: (1) magnetic sensor, (2) conductors of the compensating circuits, (3) beam splitter, (4) photo-detector, (I-IV) photo-detector quadrants, and (X, Y) output current amplifiers. Tuning of the magnetic force line Bx/B 3x10 -3 2x10-3 before tuning 1x10-3 0 after tuning 200 250 300 350 400 450 500 550 z, cm Transverse component of the magnetic field 2. Variable beam profile of the electron beam 0.6/0.9 kV 0.2/0.9 kV –0.2/2.8 kV -0.4/2.8 kV 0.05/0.9 kV –0.6/2.8 kV Electron beam distribution for different voltage on the control electrode and the anode. 3. Electrostatic bending for compensation drift electrons E=0 magnet bending B=pc/eR m V2 V B F eE e const B=0 electrostatic bending E=pV/eR R c small leakage current means a good vacuum Lanzhou, China Novosibirsk EC – 300 CSRe is prototype of the NESR electron cooler What’s new ? High Voltage power supply Single section Some sections in column Two-section dinametron allows to strongly decrease of the time of the voltage tuning oscillograph 10 M 150 M + + 1 4 2200 pF 2200 pF 68 pF 68 pF 68 M 2 68 M 3 2200 pF 68 pF 2200 pF 68 pF Scheme of one section of the voltagedoubler rectifiers. The rectifier is charged during time 2.5 ms, discharge during time 40 ms. Jointly use of two rectifiers allows reducing ramping time. In this cause ramping time is 10 ms. Time schedule (in month): Start Engineering design Materials buying Manufacture Commissioning in BINP Delivering to FAIR Assembling in FAIR Start operation in FAIR 00 00 – 06 03 – 09 06 – 18 18 – 24 24 – 26 26 – 29 29 – 32