EBIS and EBIT - Spallation Neutron Source

EBIS and EBIT
Reinard Becker, Goethe-Universität, Frankfurt, Germany
Oliver Kester, NSCL, MSU, USA

OUTLINE
1) Principles of EBIS and EBIT
2) Charge balance equations and typical solutions
3) Limits by radiative recombination and charge exchange
4) Ion heating and cooling by Coulomb collisions
5) Genealogical trees for EBIS and EBIT
6) Options now and in the future

electron gun
U(Z)
Principles of EBIS and EBIT
N
1
e
drift tubes
electron beam
pumping surface
solenoid
ion extraction
ion trapping
m
2e
PU
electron
collector
electron
repeller
ion pulse
vacuum conductance
limiters
13
1.
0510
PU
injection
P
Z
6
3 2
4
510 [ A/
V ], U 210
[ V ], 1m
N
10
Tokyo EBIT
and beam line
for extracted ions
12

Basic physics

Cross
sections
(cm 2 )
10 -15
10 -16
10 -17
10 -18
10 -19
10 -20
10 -21
Single step versus multiple step ionisation
10 1
0 -->1
1 -->2
10 2
2 -->3
3 -->4
4 -->5
5 -->6
6 -->7
7 -->8
0-->1-->2-->3-->4-->5-->6-->7-->8
This takes time – needs confinement !
10 3
argon
0 -->8
Electron energy (eV)
10 4

x10
-21
cm 2
Lotz cross sections
14
i i 1 . 5*
10
nl Ee
* Ei,
nl
3
2
1
E e Ei,
nl
2
ln
4 cm
Ar 15+ Ar 16+
Lotz ionisation cross section from 16 to 17 for Z=18
2 4 6 8 10 12 14 16 18 20
Electron Energy (keV)
Approximate ionisation energies,
ionisation cross sections
and required j-values for bare ions
Ion E i [eV] [cm 2 ] j* [Cb/cm 2 ]
C 6+ 490 7.7*10 -20 2.1
N 7+ 666 4.2*10 -20 3.8
O 8+ 870 2.4*10 -20 6.5
Ne 10+ 1360 1*10 -20 16
Ar 18+ 4400 9.5*10 -22 170
Kr 36+ 17600 6*10 -23 2700
Xe 54+ 39700 1.2*10 -23 13600
Pb 82+ 91400 2.2*10 -24 72300
U 92+ 115000 1.4*10 -24 115000

Ionisation energies by C. Moore

Charge exchange
The approximation formula of Salzborn and Müller is based on many
measurements with low chage states, however, we have nothing better!
again – multiple step CX is neglected!
i i 1
2
12 1 . 17 2 . 76
1 . 43 10 i P0
cm
In EBIS/T the pressure usually is low enough to avoid CX, only dangerous for
extremely high charge states, where ion cooling becomes necessary. More
important for EBIT!
In ECRs CX usually limits the build up if higher charge states and produces the
wide range of charge state with almost identical abundance.

10 -3
Pressure
(mbar)
10 -6
10 -9
10 -12
Charge exchange versus Ionisation
Vacuum pressure at which gain by ionization equals the loss by charge exchange for lead ion
10 A/cm 2
1000 A/cm 2
0 20 40 60 80
P b Charge states

Radiative Recombination
RR is time-reversed photo-ionisation:
σ
RR
nl
( k )
hν k
2
2
1
2m
Therefore RR cross sections may be calculated from cross sections for photo
ionisation, which is a well established procedure (T. Stöhlker, Kim and Pratt) :
e
c
2
σ
ph
nl
( k
2 2
ph
0
2 2
nl k
( 1 n κ ) g(n,l;κ,
l
2
3 Z ll12l
1
4πa
n
l
)

Electron energy (eV)
10 5
10 4
10 3
10 2
10 1
RR versus Ionisation
“Balance energy” at which the gain by ionization
equals loss by radiative recombination for lead ions
0 20 40 60 80
P b Charge states
Slow electrons are the worst enemies of highly charged ions!

Ion energy (eV)
Electron-ion heating
Radial well voltages eqU w =kT i to trap multiply charged ions heated by electrons of
energy 1 keV (dashed lines) and 10 keV (full lines), typical for ECR and EBIS/T
10 3
10 3 Ne Ar
10 2
10 2
10 1
10 1
10 0
10 0
10 -1
10 -1
CNO Ar Kr Xe Pb
0 10 20 30
Charge states
fortunately Coulomb-collisions not only heat ions (by electrons), but also can cool them by ions!
Kr
Xe
Pb

In EBIT injected ions could be trapped for hours!
only possible by evaporative cooling
Ion-Ion-cooling
Ne 22 isotope has been increased to 30% of Ne 20 in leaky mode of Frankfurt EBIS
Similar to isotope effect observed in ECRs (Drentje)
Charge spectra for argon in operation of Frankfurt EBIS beyond neutralization
O, N, C are used as coolant for argon at a pressure of 2 x 10 -10 mbar
R.Becker, M.Kleinod , and H.Klein, Nucl. Instrum. Methods B24/25 (1987) 838
Cooling by a background gas is most convenient but causes charge exchange.
Strategies for cooling with ions need to be developed for highest charge states!
8
7
6
18 17 16 14
7
6
5
6
5
4
5
Argon
32 s
10 s
3.2 s
1 s
320 ms
100 ms
32 ms
Oxygen
Nitrogen
Carbon
R. Becker, M. Kleinod, H. Thomae, and E. D. Donets, AIP Conf. Proc. 274,
edts.P.Richard, M.Stöckli, C.L.Cocke, and C.D.Lin, (1993) p. 686

dn
i
dt
n
e
n
o
e
coll
i
Charge balance
Win by ionisation, charge exchange, radiative radiation
Loss by ionisation, charge exchange, radiative radiation, confinement of heated ions
ion
n
ion
RR
n
RR
n
ion
i1
i
chex
n
chex
n
ii1
kT
w
ion
i1
ieU
exp
kT
ieU
i
w
ion
ii1
i1
i
n
i
i1
ii1
i
i1
i
i1
2-step and multiple-step processes are
important but are neglected! The overestimation
by Lotz‘s cross section
formula partially compensates for it.

Results of charge breeding simulations for Pb at 5250 eV
Relative
Abundance
%
80
60
40
20
Relative
Abundance
%
80
60
40
20
Confinement without losses EBIT mode with neutralisation at j=10
14
0.001 0.01 0.1 1 10 100 1000
j
54
Cb/cm
0.001 0.01 0.1 1 10 100 1000
j
2
2 Cb/cm
1
Relative
Abundance
0.1
0.01
0.001
Relative
Abundance
%
80
60
40
20
14
0.001 0.01 0.1 1 10 100 1000
j
Confinement with charge exchange at 10 -8 mbar Confinement with radiative recombination
54
Cb/cm2
0.001 0.01 0.1 1 10 100 1000
j
2 Cb/cm

Magnetic Emittance
The conservation of the magnetic moment (Busch‘s theorem) results in skew trajectories outside of
the magnetic field. Treating the extracted beam as a round one, results in an additional „magnetic“ emittance:
For modern EBIS and EBIT B z =3T and U 0 =20 kV, producing bare light nuclei we then obtain:
r (m)
10 -3
10 -4
abs (µ) *
5.2
5.2 x 10 -2
EBIS beams are usually smaller than 1 mm, therefore the magnetic emittance will be negligible.
For EBIT with 100 µ beams even more.
2
2eq
Br
abs
4 M U 0
Note that dimension µ for the emittance gives the same numbers as the old fashioned mm x mrad *)
m *) R.Becker and W.B.Herrmannsfeldt, Wha Pi and mrad?, Rev. Sci. Instrum.77 (2006) 03B907

40 years of EBIS history
Device year place name w/c/r Bmax length N- special
IEL-I/II 1968 Dubna Donets w 0.4 0.16 proof of principle
SILFEC 1969 Orsay Arianer w 0.8 0.8 8E10 proof of principle
TOFEBIS 1971 Frankfurt Kleinod/Becker w 0.4 0.1 1E5 proof of principle for dc
KRION-I 1972 Dubna Donets/Pikin c 1.2 1.2 1E11 Synchrophasotron injector
Texas-EBIS 1974 Texas Hamm w 0.4 0.2 1E10 Cyclotron
KRION-II 1974 Dubna Ovsiannikov/Donets c 2.2 1.2 1E10 atomic physics
EBIS 1980 Frankfurt Becker/Kleinod c 5 0.8 1E7 atomic physics
NICE 1981 Nagoya Ohtani c 3 0.6 1E4 atomic physics
CRYEBIS-I 1981 Orsay Arianer c 3 1.66 1E8 injector for SATURN
CEBIS-I 1982 Cornell Kostroun w 0.42 0.5 1E5 atomic physics
CRYEBIS-II 1984 Orsay Arianer r 5 1.66 1E10 same as CRYSIS,
DIONE 1984 Saclay Faure r 6 1.2 5E10 SATURNE injector
BEBIS 1984 Berkeley Brown w 0.3 0.6 1E6 worked later at SNLL
CEBIS-II 1986 Cornell Kostroun c 3 0.4 6E10 atomic physics
Mini-EBIS 1987 Tokyo Okuno LN 0.5 0.5 1E4 7 sources for atomic physics
ESIS 1990 Dubna Donets c 3.5 1.2 5E10 Nuclotron Au injector
KRYEBIS 1990 KSU Stöckli r 5 1 8.5E9 atomic physics
S-EBIS 1990 SNLL Schmieder c 5 1.0 2E10 worked later at BNL
RHEA 1991 Saclay Faure w 0.5 1.0 2E11 died during birth
MEDEBIS 1993 Frankfurt Kester/Becker w 0.8 0.25 5E10 hadron therapy
KRION-S 1994 Dubna Vadeev/Donets c 2.2 1.2 1E8 Nuclotron injector
XEBIST 1994 Frankfurt Mücke/Becker w 0 0.4 1E5 without Bz, rel. focusing
TestEBIS 1997 BNL Beebe/Pikin c 5 0.7 1E12 obtained 70% ion yield
REXEBIS 2000 CERN Wenander/Liljeby c 2 0.8 5.4E10 charge breeding at Isolde
EBIS 2000 Arhus Schmid w 0.1 0.6 1E10 ASTRID injector
MIS-1 * 2001 Novosibirsk Abdulmanov c 3 0.7 1E12 operation in 2010 ?
MAXEBIS 2004 Frankfurt Becker/Kleinod c 5 0.8 3E11 moved to GSI in 2005
D-EBIS 2005 Dresden Zschornack pm 0.4 0.06 6E8 HCI applications
D-EBIS-A 2008 Dresden Zschornack pm 0.6 0.06 1.22E9 HCI applications
RHIC-EBIS * 2009 BNL Beebe/Pikin c 6 1.5 2.2E12 new HI injector for RHIC
D-EBIS-SC * 2009 Dresden Zschornack r 6 0.2 2E10 carbon therapy
KRION-6T * 2009 Dubna c 6 prototype for ESIS scaling
TESIS-5T * 2010 Dubna c 5 ESIS with tubular beam
* not yet in operation
no longer in operation

BNL Test-EBIS

BNL-EBIS results and projections
4 – 8 mA !

In the paper
„Instabilities“ in BEBIS created EBIT
„Measurement of instabilities and ion heating in an electron beam ion source“,
LBL 19853, M.A. Levine, R.E. Marrs and R.W. Schmieder measured instabilities
in the Berkeley EBIS.
C.Litvin, M.Vella, and A.Sessler, Nucl. Instrum. Meth. 198 (1982) 189 concluded
that only a short electron beam may be stable.
M.A.Levine, R.E. Marrs, J.R. Henderson, D.A. Knapp and M.B. Schneider, Nucl.
Instrum. Meth. B43 (1989) 431 then constructed the first EBIT and
R.W.Schmieder and C.L.Bisson, Rev. Sci. Instrum. 61 (1990) 256 reconstructed
the Berkeley EBIS and made it work – without instabilities
how to make a good decision on a wrong judgement!

Device year place name w/c/r Bmax length N- special
EBIT-I 1988 LLNL Levine c 3 0.02 1E5 spectroscopy
EBIT 1988 Oxford Silver c 3 0.02 1E5 spectroscopy
EBIT-II 1990 LLNL Marrs/Knapp c 3 0.02 1E6 spectroscopy
EBIT 1990 NIST Gillaspie c 3 0.02 1E5 spectroscopy
S-EBIT 1990 LLNL Marrs/Schneider c 3 0.02 4E4 spectroscopy
S-EBIT 1993 Tokyo Ohtani c 3 0.03 8.9E6 atomic physics
EBIT 1997 Berlin Radke c 3 0.02 1E5 spectroscopy
D-EBIT 1997 Dresden Zschornack pm 0.25 0.02 1E8 spectroscopy
F/H-EBIT 1999 Freiburg Crespo r 9 0.04-0.3 2E10 atomic physics, spectroscopy
EBIT QUB * 2005 Belfast Currell pm 0.65 0.02 2.4E6 atomic physics, spectroscopy
S-EBIT 2005 Shanghai Wu c 3 0.02 1.3E7 spectroscopy
FLASH-EBIT 2006 Heidelberg Crespo r 6 0.05-0.3 2E10 atomic physics, spectroscopy
TITAN-E * 2006 TRIUMF Crespo/Dilling r 6 0.10 2E10 charge breeding
EBIT 2007 Stockholm Fritioff c 3 0.02 1E5 atomic physics
ReA3-EBIT * 2008 MSU Schwarz/Crespo r 6 0.80 1.5E11 charge breeding
HD-II EBIT 2008 Heidelberg Crespo/Schwarz r 7 0.3 1E11 atomic physics, spectroscopy
CoBIT * 2008 Tokyo Nakamura LN 0.2 0.03 1E8 atomic physics
* not yet in operation
20 years of EBIT history
no longer in operation
charge breeders TITAN, ReA3, and HD-II are certainly EBISes !

N -
10 12
10 11
10 10
10 9
10 8
10 7
10 6
10 5
10 4
EBITSs, applications, technology, genealogics
P = prototype, S = synchrotron, C = cyclotron, A = atomic physics, B = (charge) breeder, M = multi purpose
Letters: normal conducting, cooled by LN , cooled by LHe, cooled by refrigerator(s), permanent magnets
2
Lines: Dubna, Orsay, Frankfurt, Livermore, Japan, Heidelberg, BNL, Dresden
13
10
P
P
P
S
A
C
A
S
A
A
S
S
C
A
A
A
S
S
A
A
A
A
A
1970 1980 1990 2000 2010
Year of start
S
A
P
S
P
A
A
M
B
A A
S
A
A
A
A
B
S
B
S
A
A
A

future applications for EBITSs

Analyzing
magnet
Charge breeding
>> „outsourcing“ of the production of singly charged ions

Super-compression in CRYEBIS-I (1979, 1982 )
J.Arianer et al., IEEE Trans. Nucl. Sci. NS-26 (1979) 3713
Abnormal short ionisation times were reportet. The
estimated current density increased for heavier
atoms up to 10 5 A/cm² at Xenon
Is this the reaction of a Brillouin focused beam on
space charge neutralisation in the magnetic
compression region?
M.Olivier et al., IEEE Trans. Nucl. Sci NS- 30 (1982) 1463

Hadron therapy

0.6
Relative
abundance
0.4
0.2
average
current density
in A/cm²
31,600
10,000
3,160
1000
200 400 600 800 1000
Electron Energy (keV)
10 keV
31 keV
100 keV
316 keV
0.1 0.316 1 3.16
trap length in cm
EBIT with relativistic pinching
1000 keV
example of 500 keV
A Design Study for a European Super - EBIT / EBIS
R. Becker 1) , E. D. Donets 2) , M. Kleinod 1) , H. S. Margolis 3) and J. D. Silver 3)
1) Institut für Angewandte Physik der Universität Frankfurt, Germany
2) Laboratory of High Energies, JINR, Dubna, Russia
3) Clarendon Laboratory, University of Oxford, England
91
90
92
89
10
Insulator
0.552 m
Anode
Cathode
and Wehnelt
0.2 m
1 m
gate
valve
gate
valve
Trap
Collector
or gun
cryo panel
cryo panel
Gun
or collector
magnetic
lenses and
steerers
magnetic
lenses and
steerers

Donet‘s ESIS and TESIS
Electron String Ion Source Tubular ESIS
TABLE 1. Comparison of Power Consumptions for EBIS and ESIS
N e /m EBIS ESIS
10 11 10 kW 50 W
10 12 200 kW 200 W
10 13
10 14
10 15
5000 kW 2 kW
20 kW
200 kW

Conclusions
EBISes and EBITs are all the same ! Let‘s calls them EBITSs !
For highest charge states ion-ion-cooling needs further development
Neutralisation and self-compression of the electron beam is promising
MEDEBIS for carbon therapy with single-turn injection and extraction
Reflex mode will become more interesting when easier to control
SUPER-EBIT with Ee > 500 keV should be build
More charge breeder EBISes or EBITs to come
BNL leads the classical approach !
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