The Electrostatic Cryogenic Storage Ring CSRa storage device for atomic, molecular and cluster ion experiments
35 m circumference
Max-Planck-Institut für Kernphysik, Heidelberg, Germany
The CSR Project at MPI-K
HC Injector
Postaccelerator
13 MV Tandem
TSR
CSR
(planned)
H D neutral
CSR Cryo-System
3 MV
Van de
Graaf
Ring at 2-10 K ?
 XUHV
  ~ 1000s
=0
J=1
Electrostatic ?
Example:
HD+
+
e-
=H+D
 Heavy
molecules
Robert von Hahn for the CSR-Team
Astrophysics
Interstellar clouds consist of 90% H, 10% He and
100ppm “Metals” . Chemistry is driven by molecular
ion intermediates.
Quantum
Chemistry
Test quantum chemical models for the dynamics of
small molecular ions, extend understanding of larger
(bio-) molecules.
Cluster Physics
Heavy-Ion
Storage
Investigate the individual and collective behaviour of
ions stored in a ring or trap for very long times.
Probe the cooling and decay of small and larger cluster
ions, over an extended range of temperatures.
Lifetime
lifetime of single charged ions / molecules
+
50
Xe
T [s]
40
Li
KEK ion
E = 20 keV
KEK molecules
E = 20 keV
30
NO
+
Ar +
O2
20
10
N2
+
Be
Capture
+
H2 O
+
+
TSR
+
+
Mg
Ne
+
O
+
N
+
Stripping
p = 5 10
-11
mbar
0
0.1
1
Energy range CSR
10
100
1000
E/A [keV/u]
Robert von Hahn for the CSR-team
Cryogenic Pumping of Hydrogen
H2 @ 5 K
Vapor pressure: 10-5 mbar
Density: 2*105 cm-3
H2 @ 2 K
Vapor pressure <10-15 mbar
Density: few 1000 cm-3
The Cryogenic Storage Ring (CSR)
Isolation
Vacuum
p10-6 mbar
•20-300 keV
•> 100 a.u.: electrostatic optics
•Rotationally cold ions: <10 K
•Long storage time:
60 Deflector
•Cryo-pumping of H2: 2 K
Quadrupole
•Cooling by liquid helium
•Room temperature operation
•Baking to 350°C
•600 K temperature range
•Electrode positioning: 0.1 mm
•Technological challenges foreseeable
•Need prototype device
R. von Hahn et al., Proc. EPAC 2008
390 Deflector
60 Deflector
40 K Shield
Concrete
Foundation
80 K Shield
Inner Vacuum
Chamber
p<10-13 mbar RTE
Beam preparation
Ion beam trap
4m
Ion source
Robert vonVol.81,
Hahn for Issue
the CSR-Team
M. Lange et al., Review of Scientific Instruments,
5, 2010
Linear Electrostatic Ion Trap
Injected ion beam
Middle chamber
~1 m
~3 m
Electrostatic
ion trap
Gold plated
electrodes
Pumping
Robert von Hahn for the CSR-Team
Cooling techniques and thermal shielding
2K cooling units
Isolation vacuum
10-6 mbar
2-10 K
Cold chamber
Experimental vacuum
10-13 mbar
Robert von Hahn for the CSR-Team
20 m3
buffer
12 bar
LN-buffer
container
Cold box
Connection
box
Riezlern 2008
Robert von Hahn
CTF Cryogenic Design
Interior circuit
1.8 K He out (gas)
{
Exterior circuit
1.8 K He in (liq)
{
80 K He out (gas)
5 K He in (gas)
Auxiliary cooling unit
Ring cooling units
Liquid He level probe
Temperatur distribution
Robert von Hahn for the CSR-Team
Principle of the Ion Beam Trap
M. Dahan et al., Rev. Sci. Instrum. 69 (1998) p.76.
Ion Trapping & Detection
Produces N2+ ions
with energies of 2-10 keV
Counting of neutral fragments on a chevron MCP
Detection
1

Beam cleaner
Cryogenic ion trap
 n     v  p
~ 4-5 µs
Static
electrodes
N2+
mm
v  200
µs
Ion source
Only
ions
Switched
electrodes
Bunch length
definition
• Trapping of N2+ ions by switching the electrodes
• After ~400 ns electrode voltage at 95%
• Neutralisation by electron capture of the restgas (mainly H2 at 2K)
Robert von Hahn for the CSR-Team
Particles
from source
Storage Lifetime
2008: First storage of ions in CTF under cryogenic conditions
However: lifetime limited to 24 s – much shorter than expected
Improvements in 2009:
•Reduced ripple on trap
voltages (fast HV switches)
•Cryogenic chamber baked
for better vacuum at RT
•Improved differential
pumping after ion source
•Improved shielding against
infrared radiation at trap
entrance+exit
Feb+March 2009: 340 s storage lifetime!
With collision cross-sections from the literature, the new lifetime would translate to a
residual gas density of 44000 cm-3 or 1.6*10-12 mbar (at Room Temperature).
Robert von Hahn for the CSR-Team
Worsening the pressure by opening the
valve to turbo pump
Turbo
pump
Life Time
Robert von Hahn for the CSR-Team
Trap Vacuum
CTF pressure: 8*10-14 mbar
Cryogenic pumping of hydrogen at 1.8 K: Expect vacuum of few 10-13 mbar (RT equiv.)
Most likely particle loss from trap not dominated by residual gas collisions
•
•
Model: 2 loss mechanisms:
– residual gas collisions
(proportional to pressure)
– ion evaporation from trap
acceptance volume (constant)
Total rate from particle loss:
dN/dt = k N(t)
k = kc+ks+kev
•
Neutral particle rate:
Ro = ½ αεnNo
Robert vonVol.81,
Hahn for Issue
the CSR-Team
M. Lange et al., Review of Scientific Instruments,
5, 2010
New purpose for the CTF
•
•
Optimization for CSR 
Cryogenic test and procedures
•
8*10-14 mbar proved
•
New device for research with best
vacuum pressure for large
instruments, first experiments with
Al-clusters have been started
Robert von Hahn for the CSR-Team
The Self-Bunching Effect
f f
E 
E E
Experimental Observation
of Bunch Decay (7.1 keV N2+)
Other EIBT: 90-100 ms
No disentangling between
beam and ion bunch losses
M.Froese, Ph.D. thesis
2.6 m
Robert von Hahn for the CSR-Team
Support Concept
80 K
60 cm
40 K
CSR Mechanical Layout
Isolation Vacuum Chamber
Isolation
Vacuum
p10-6 mbar
60 Deflector
390 Deflector
He Gas
60 Deflector
Quadrupole
Inner Vacuum
Chamber
p<10-13 mbar
Liquid He
40 K Shield
Concrete
Block
80 K Shield
Robert von Hahn for the CSR-Team
Cryostat chambers
10 t horizontal force
2 linear & 1 rectangular chamber /corner
4 middle section chambers
2 von
bellows/linear
section
Robert
Hahn for the CSR-Team
Schema of the support system
Cold Box
Connection Box
Supports for 39o deflectors
Mechanical anchoring due to
10 t horizontal force
Targets to determine the beam axis (50µm)
Robert von Hahn for the CSR-Team
Support concrete blocks
Robert von Hahn for the CSR-Team
Cryostat chambers
•
•
•
•
•
Stainless steel frame & aluminum plates
Plates perform the stability
Thickness of bottom plate 80 mm
Thickness of other plates 60 mm
Good access
Movable connection
Robert von Hahn for the CSR-Team
Robert von Hahn for the CSR-Team
CSR Mechanical Layout
quadrupol
6o bender
39o bender
5/corner
Robert von Hahn for the CSR-Team
39o deflector chamber
Stainless steel chamber
• Fulfilles pressure directive
•Welded with filler
•Material 316L
•Copper layer for temperature levelling
•Equiped with nonmagnetic heater wires
Robert von Hahn for the CSR-Team
Quadrupole chamber
bottom
supports
Support for quadrupole
up
Flanges for
feed throughs
Connection to
Robert von Hahn for the CSR-Team
cryogenic tubes
Quadrupole
•Wire eroded electrodes from aluminum
•Hyperbolic shape
•Aluminum support
•Isolation by alumina rods
Robert von Hahn for the CSR-Team
lifetime of single charged ions / molecules
+
50
Xe
T [s]
40
Li
KEK ion
E = 20 keV
KEK molecules
E = 20 keV
+
+
Be
Life-time of singly charged ions and
molecules in a storage ring
Increased lifetimes of singly
charged ions and molecules of up
to a factor 100 – 1000
30
+
NO
+
Ar +
O2
20
10
N2
H2 O
TSR
+
+
+
+
Mg
Ne
+
O
+
N
p = 5 10
-11
mbar
0
0.1
1
10
100
Low thermal-radiation
environment
Temperture variable environment
1000
XUHV conditions
E/A [keV/u]
T [s]
•merged beam experiments
30
28
26
24
22
20
18
16
14
12
10
8
6
4
2
0
100
lifetime of bio-molecular ions at
KEK electrostatic storage ring
aniotensin (1+)
arginine
dimer (1+)
insulin from bovine
pancreas (5+)
respine (1+)
insulin chain B (3+)
p = 5 10
1000
-11
mbar
10000
•Rotationally controlled low
energy reaction studies
• fixed target collisions with full
kinematic
•with molecules or highly charged
ions at low velocities
A
KEK data from T. Tanabe , KEK preprint 2001-44 and contribution to 13 th symposium
on accelerator science and technology, Osaka, October 2001
Conclusions and Outlook
• First successful operation of a large cryogenic ion beam
trap
• Determined pressure to 8*10-14 mbar
• Successful test of CSR mechanical and cryogenic design
• First observation of the decay of bunches in an EIBT
• Observation of decay law for Aln- over very long time, in
low thermal-radiation environment
• Strong deviations from the 1/t decay law oberserved for
Al4- and Al5- clusters
• Moved trap for further experiments to another lab
• Proceeded with ordering and started assembly of CSR
–
–
–
–
All cryostat chambers delivered, ¾ assembled
All inner chambers (1 corner) delivered
Focussing elements in production
Shield beeing assembled
Robert von Hahn for the CSR-Team
Outlook: FLAIR @ FAIR
Facility of Low Energy
Antiproton and Ion
Research (FLAIR)
Antiproton
Collector
Ring
LSR: magnetic ring: 30MeV-300 keV
ESD Stockholm
2007 ring: 300 keV-20 keV
USR:
electrostatic
Robert von Hahn for the CSR-Team
CTF/CSR Team
F. Berg, K. Blaum, F. Fellenberger, M. Froese,
M. Grieser, M. Lange, F. Laux, S. Menk,
D. Orlov, R. Repnow, A. Shornikov, T. Sieber,
R. v. Hahn, A. Wolf
Thank you for your attention!
Robert von Hahn for the CSR-Team