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NESR(Reva)

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“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
пЃІ
пЃІ 4пЃ° n e 4 L
e
C v
F пЂЅ
,
3
me
ve пЃћ
free C o u lo m b co llisio n
пЃ›
m u ltip ly co llisio n s v пѓЋ v e пЃјпЃј , п‚Ґ
пЃ›
пЃќ
stro n g m ag n etizatio n v пѓЋ v e пЃјпЃј , п‚Ґ
пЂЁ
2
mv
пЃІ
пЃІ 4пЃ° n e 4 L
v
e
C
F пЂЅ
,
2
2
me
v пЂ« v e || v e пЃћ
пЃІ
пЃІ 4пЃ° n e 4 L
v
e
C
F пЂЅ
.
3
2
me
2
2
v пЂ« v e ||
пЂЁ
пЃќ
e
пЂ©
пЂ©
V
пЃ·H
2
e
пЂј пЃІ пЂј
V
пЃ·H
пЂј пЃІ пЂј пЃІL
пЃІL пЂј пЃІ пЂј
V пѓ—пЃґ
1 пЂ« пЃ· peпЃґ
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
E nerg y of the referen ce ion (A /Z п‚»248/92 п‚»2.7)
740 M eV /u.
M ax im um electron energy
450 kV
E lectron current
2A
D iam eter of th e electron beam in the coolin g section
0.5 -2 cm
M agn etic field in the coo ling section, G
2000
G un solenoid field, G
4000
M ax im u m acceleratin g v oltage
500 kV
R am ping of the electron energ y (400 k V – 2kV )
less 1 s
N um ber of dinam etron section
25
V oltage per dinam etron section
20 kV
S F 6 pressure
1.7
L en gth o f cooler section, cm
500
R esidual pressure in the cooling section
F raction of the orbit
10
-1 0
– 10
-1 1
0.023
torr
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
L as er
El ectr o n ic un it
P r ea m pli fier
Y
P r ea m pli fier
РїСЂРµ Рґ
РїСЂРµ Рґ-
M o d u lation
In teg r ato r
S yn ch r.
d etect or
I nteg r ato r
S yn ch r.
d etect or
A r r ay
X
III
Cu r r ent sen s or s
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
B x/B
3 x1 0 -3
2 x1 0 -3
before tuning
1 x1 0 -3
0
after
tuning
200
250
300
350
400
450
500
z, c m
Transverse component of the magnetic field
550
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
F пЂЅ
mV
R
2
пЂЅ eE пЂ« e
пЃ›V
п‚ґ BпЃќ
c
пЂЅ const
E=0 magnet bending B=pc/eR
B=0 electrostatic bending E=pV/eR
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
S ing le sect io n
S o m e sect io ns in co lu m n
Two-section dinametron allows to strongly
decrease of the time of the voltage tuning
oscillograph
10 MпЃ—
150 MпЃ—
+
+
1
4
2200 pF
2200 pF
68 pF
68 pF
68 MпЃ—
2
68 MпЃ—
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
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