Investigation of ion capture in an Electron Beam Ion Trap ......Study ion reflection with time-of-flight spectra Intuitively determine ion reflection region Maximize the transport

Kritsada Kittimanapun

ATD seminarAugust 26, 2014

Investigation of ion capture in an Electron Beam

Ion Trap charge-breeder for rare isotopes

• Electron beam ion source/trap principle

• EBIT charge breeder for ReA

• Simulation of acceptance and capture

efficiency of NSCL EBIT

• Experimental results

• Conclusion and outlook

Outline

K. Kittimanapun Slide 2

Electron beam ion source/trap principle

Slide 3K. Kittimanapun

EBIT : device to create highly charged ions by electron impact ionization

1+

Q+

Outer

barrier

Inner

barrier

Continuous injection:

(no buncher needed)

Pulsed extraction:

Electron beam: electron impact ionization,

radial confinement

Magnetic field: electron beam compression

Trap electrode: axial confinement

Breeding time :

e = elementary charge

σEI = electron impact ionization

cross section

je = electron beam current density

Trapping condition:

Charge state changes 1+ → 2+ in trap

Extraction process:

Outer barrier pulsed to trap potential

Super Users Meeting 8/11 4

Other EBIS/T around the WorldFlash-EBIT

TITAN / TRIUMF

REX-EBIS @ CERN

Tokyo

VancouverNSCL

Geneva

Dresden

LLNL

Heidelberg

Stockholm

Belfast

Frankfurt

Shanghai

Applications:•Atomic spectroscopy

•Surface interaction

•Charge breeder

•Charge breeder

(post-accelerator for rare

isotope beam)

Brookhaven

BNL-EBIS

Dubna

ANL

Kielce

TITAN-EBIT

S-EBIT

� REXEBIS at CERN was first to successfully use EBIS charge-breeder for rare isotopes� NSCL: in commissioning, ANL/TRIUMF: under construction / in planning

ReA post accelerator at NSCL


ReA

post-accelerator

Stopped beam area

Coupled cyclotron

facility (> 80 MeV/u)

What is ReA :

Post-accelerator to reaccelerate rare isotopes to an energy of a few hundred

keV/u – several MeV/u

Purpose:

oStudy key reactions in nuclear astrophysics at near-stellar energies.

oNuclear structure studies near/above the Coulomb barrier.

A1900 separator

High energy

beam

Low energy beam

Intermediate

energy beam

Reaccelerator concept for rare isotope beam


Reacceleration of highly charge ions: compact, cost effective → charge breederReacceleration of highly charge ions: compact, cost effective → charge breeder

EBIT charge breeder: Short breeding time, Clean beam, High efficiency

(injection, ejection, narrow charge state distribution)

0.3 - 3 MeV/u for 238U

0.3 - 6 MeV/u for light

elements

Linear accelerator

SRF

cryomodules

Charge-over-mass

separator

�Fast (breeding time < 50 ms)

� Short half-lives

• High electron beam current density (large electron beam

current + strong magnetic field)

�Large capacity (1010 positives charges)

� High intensity (FRIB)

• Large trapping region + high electron beam current

�High efficiency (20 – 50%)

� Rare isotope

Requirements for a rare-isotope charge breeder


EBIT charge breeder efficiency


e- beam

Ion

trajectory

Full overlap,

- ideal !

Partial overlap

- nice, but bad !

No overlap

- no capture

y

x

Efficiency of EBIT charge breeder depends on …

� Injection and extraction efficiency

• Good transport

� Narrow charge-state distributions :

• Proper electron beam energy and breeding time

� Capture efficiency

• Fast charge breeding into charge state 2+

• Good overlap between ion and electron beam

Importance of overlap of electron and

ion beam for capture of ion beam

NSCL electron beam ion trap

Electron

gun

MagnetElectron

collector


Electron gun

Helmholtz coils Solenoid

Superconducting magnet Electron

collector

Solenoid :

low compression, long trap,

large acceptance

Helmholtz coil:

high compression, short breeding time

EBIT design parameters:� High beam current < 2.5 A

� Magnetic field up to 6 T

� High current density 104 - 105 A/cm20.8 m

My EBIT Research


Study ion capture in the ReA EBIT : simulation

�Develop a code to study physics of EBIT

� Optimize EBIT acceptance, support commissioning

� Benchmark with reliable tools to validate code

�Study capture efficiency

� EBIT parameters: electron beam current, magnetic

field, trap size, ion beam energy etc.

� Optimize ion transport optics

Study ion capture in the ReA EBIT : experiment

�Develop new technique to optimize ion injection

and determine space charge potential

�Investigate capture efficiency for different EBIT

parameters

�Study charge breeding process and measure

effective electron beam current density

Compare simulation against experimental results and

use as guidance for EBIT operation

K. KittimanapunSlide 11

My EBIT Research

• Electric field: SIMION

• Magnetic field: Analytic solution for coil set

• Space charge potential: analytical model

• Ion dynamics : Runge-Kutta integrator

• EI cross section: Lotz formula*


How: Calculate ion trajectory with Monte Carlo

electron impact ionization (EI)

Use:

Numerical Simulations

Develop NSCL EBIT Simulation Code (NEBIT)

*W. Lotz, Z. Phys 206:205, 1967

NEBIT: Optimize acceptance and study ion behavior in EBIT

1000 1500 2000 2500

0

2

4

6

8

e-beam radius

Axial B-field

Electron beam radius (mm)

Bz (T)

z (mm)

6T

0.04 mm

E-beam current 0.8 A

50

52

54

56

58

60

Total potential

Drift tube potential

Space charge potential

Space charge potential (kV)

Potential (kV)

z (mm)

-1.2 kV

0.01

0.1

1

10

100

-1.2

-1.0

-0.8

-0.6

-0.4

-0.2

0.0


Physics for EBIT simulation

Electric field:

Electrode voltages + space charge

Magnetic field:

“1T (solenoid) -6T (Helmholtz)”

configuration

Sp

ace

ch

arg

e

po

ten

tia

l (k

V)

Axial coordinate (mm)

Sp

ace

ch

arg

e

po

ten

tia

l (k

V)

Axi

al m

ag

ne

tic

fie

ld (

T)

Po

ten

tia

l (k

V)

Collector Trap centerBarrier

Ion beam e beamSample trajectory

(electron beam)

Collector Trap centerBarrier

Ion beam e beam

Sample trajectory


Physics for EBIT simulation

Monte Carlo

Ionization process :

Captured ion

Breeding process

-4 -3 -2 -1 0 1 2 3 4

-40

-30

-20

-10

0

10

20

30

40

a (mrad)

x (mm)

Acceptance

• Acceptance = phase space of captured ions

• Capture probability = overlap of ion beam emittance and acceptance

From acceptance to capture probability


0 10 20 30 40 50

0.0

0.2

0.4

0.6

0.8

1.0

1.2

Capture probability

ε (π mm mrad)

Capture probability

60 keV ion beam

0.8 A electron beam

emittance

• Test of energy conservation along ion trajectory

• Comparison of

– capture efficiency between NEBIT and analytic

formula

– charge evolution between NEBIT and CBSIM

– capture efficiency between current and earlier

versions of NEBIT

– acceptance from NEBIT and analytical formula

NEBIT Code Benchmarking


NEBIT Code BenchmarkingComparison of acceptance from NEBIT with analytical formula

K. Kittimanapun

*F. Wenander, CERN-OPEN , 2000-320

Slide 17

Analytical formula of EBIT acceptance* : electron beam, radius, and magnetic field

� Determine maximum number of ions fit into electron beam (exclude EI process)

Acceptance (Ee 12.5 keV, Ie 1 A, B-field 6 T):

Analytical value = 2.22 πmm mrad

NEBIT value = 2.20 πmm mrad (0.9% error)

-0.4 -0.2 0.0 0.2 0.4

-10

-5

0

5

10 x-direction

y-direction

Analytical value

ax, ay (mrad)

x, y (mm)

Acceptance phase space

Both results are consistent

and code is ready to be used

Electron beam

Ion trajectory

�Measurement of emittance of beam from test ion source

� Preparation of ion injection

• Measure axial energy spread of ion beam

• Optimize injection with new technique

� Investigation of capture process

• Capture efficiency vs. EBIT parameters (electron

beam current, trap size, and trap potential )

� Study of charge state evolution

• Determine optimum charge breeding time and

calculate effective current density

Experimental Studies


New approach to optimize ion injection


Study ion reflection with time-of-flight spectra� Intuitively determine ion reflection region

� Maximize the transport efficiency into the EBIT trap

BOB1

MCP

K+

K+

Ion reflection occurs due to axial kinetic energy < electric potential

EBIT

Q/A

separatorIon source

Deflector

Recording of time-of-flight signal starts when the

deflector voltage changes from injection to extraction

voltage



Trap entranceInner barrier (LTE4)

With this technique:

• Ions mostly reflect off inner barrier and trap entrance

• By monitoring ion current with FC, more than 95 % of detected

beam reached the EBIT trap center

K+

LTE1

MCP signal vs time-of flight

MC

P s

ign

al

(mV

)

Investigation of Capture Efficiency

0

20

40

60

80

100

120

K14+

K8+

K9+K

10+K11+

K12+

K13+

K15+

K16+

K17+

K18+

Current@

BOB4 (pA)

Q/A

W ith K+ injection

Electron beam current 126 mA

Electron beam energy 19.5 keV

Continuous injection with

5 Hz repitition rate


Total efficiency :

Q/A spectrum of highly charged K in EBIT

K18+

K17+

K16+

K15+

K14+

K13+

K12+

K9+K11+

K8+K10+

0.33 0.25

K. Kittimanapun


Slide 22

Capture efficiency vs electron beam current

5.5 π mm⋅mrad

1.4 π mm⋅mrad

Larger electron beam current leads to → higher electron beam current density

→ faster process for 1+ → 2+ charge state

→→→→ higher capture efficiency

Experimental and simulated efficiencies follow the same trend but differ significantly

Maximum efficiency 2.3%

-70 -60 -50 -40 -30 -20 -10

1

2

3

4

5

6

Upper bound simulated efficiency / 7

Lower bound simulated efficiency / 7

experiment

Capture efficiency (%)

Trap depth (V)


Capture efficiency vs trap potential depth

Trap potential needs to be optimized :

Shallow trap potential → small axial kinetic energy

Deep trap potential → efficiently trap ions of 2+ charge state

Optimized trap potential is at -30 V


5.5 π mm⋅mrad

1.4 π mm⋅mrad

K. Kittimanapun

Investigation of My Capture Efficiency

Slide 24

Why is capture efficiency overpredicted by factor 7?

Possible reasons :

• Experimental emittance > expected emittance ?

With large emittance, simulation overpredicts by a factor 3

• Ion beam misalignment with electron beam?

NEBIT expects factors of 1.2, 2 for 0.5, 1 mm misalignment

• Limitation of trap capacity ?

EBIT trap overfilled with 1.4 nA injected beam

Including this factor, overprediction drops factor of 1.5

• Electron beam not uniformly distributed ?

Study of charge state evolution of K ions


Q/A0.20.33

Determination of effective current density

Effective electron beam current density for

K12+ = 157 A/cm2 and K16+ = 243 A/cm2

Charge evolution of potassium

12+

16+

A/cm2

Study of charge state evolution of K ions


High charge state → small radius

→ high current density

Simulation of electron beam current density

Distribution of electron beam current density

Overprediction of capture efficiency can be explained if K1+ ions

travel in a region of low electron beam current density


K12+

K16+

K12+

K16+

K1+

• Transport efficiency of 95% has been achieved with a new

technique to optimize ion injection

• Simulation overpredicted the experimental capture

efficiency of 2.3% by a factor 7

• Effective electron beam current density was determined

• Distribution of electron beam current density is an

important factor for overprediction

• NEBIT can be improved by importing the electric field of

space charge from SIMION and including different electron

beam current density distribution

Conclusion and my outlook


Facility of Rare Isotope Beam (FRIB)


Project completion : June 2022

• Georg Bollen (Advisor)

• Oliver Kester

EBIT Team:

• Stefan Schwarz

• Alain Lapierre

• Thomas M. Baumann

Acknowledgement

K. Kittimanapun

Thank you for attention!Thank you for attention!Thank you for attention!Thank you for attention!

Slide 29

Committee members:

• Daniela Leitner

• Norman Birge

• Vladimir Zelevinsky

ReA people and many more…


• Electron potential

• Herrmann radius

Electron potential and Herrmann radius


• Electron impact ionization

• Radiation combination

Charge evolution (1)


• Charge exchange

• Ion heating by electron beam



• Ion-ion energy exchange



Which breeder – RequirementsBreeder requirements

• High efficiency, breed into 1 charge state

• Breeding times ~ 10 ms

• Beam intensity ~ 109 ions/s

• EBIS/EBIT charge breeding is the method of choice over ECRs

for reacceleration of beams with rates as expected for ISF and similar facilities

• EBIS + post-accelerator concept already successfully in use at REX-ISOLDE at CERN

• Continuous injection

• High acceptance, low emittance

• Fast and slow extraction

%10 ms50 msBreeding times

nopresent performance :

25 - 50% of values

present performance:

20% of valuesRisk

>> 109/s> 109/s>> 109/sBeam limit

3 – 1212% (4 CS)> 40% (1 CS)<20% (1 CS)ε (A=200)

3 – 1016% (3 CS)> 50% (1 CS)<20% (1 CS)ε (A=100)

1.5 – 340% (1-2 CS)> 60% (1 CS)<20% (1 CS)ε (A<40)

ε(EBIT)/ε(1+)1+ schemeEBIT/EBISECR

Single charge state

Expected performance of ECR and EBIS/T:

Mini workshops at NSCL with external experts, January and June 2006



Electron current 2.4 A

Magnetic field 6 T

Initial electron beam energy 12.5 keV,

SC potential -3.37 kV (without correction)

SC potential -4.12 kV (with correction)

∆U = 0.75 kV

1 .0 1 .2 1 .4 1 .6 1 .8 2 .0 2 .2 2 .4

2

4

6

8

1 0

1 2

1 4

1 6

z (m )

Electron energy (keV)

1 . 0 1 . 2 1 . 4 1 . 6 1 . 8 2 . 0 2 . 2 2 . 4- 5

- 4

- 3

- 2

- 1

0

1

2

3

Space charge potential (kV)

z ( m m )

Electron beam energy

• Drift tube potential

• Space charge potential

E0

E1

En

U0

Un U1

� Iterative solution for Electron

beam energy

Test of energy conservation


Parameters : Fe-56, 60 keV, 1T6T magnetic field configuration

Energy is conserved with negligible deviation < 1% space charge potential

Aim : To check numerical error from calculation if NEBIT handles forces correctly

0.0 0.5 1.0 1.5 2.0 2.5

0

5

10

15

20

25 x = 2.31 mm, y = 0.12 mm

ax= 13922 m/s, ay= 3946 m/s

Deviation of total energy (eV)

z (m)

Off-axis

On-axis

0.0 0.5 1.0 1.5 2.0 2.5

0

10

20

30

40

50

60

Energy (keV)

z (m)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

Energy of both on- and off-axis

x = 2.31 mm, y = 0.12 mm

ax = 14286 m/s, ay = 1192 m/s

On-axis

Off-axis

Deviation of

total energy (eV)

Total energy

Potential energy

Kinetic energy

Ie= 1A

Ie= 2.5A

With space charge (Ie =1A)Without space charge

Ion trajectory validation


Ion beam parameters -> Fe-56, 60 keV, xini = yini = 0.5 mm , axini = ayini = 0 mrad

EBIT parameters -> 1T6T magnetic field configuration

Trajectory deviation

Trajectories are identical as the deviation is negligible

0 . 0 0 . 5 1 . 0 1 . 5 2 . 0

- 1 . 0

- 0 . 5

0 . 0

0 . 5

1 . 0 N E B I T

S I M I O N w i t h p o i s s o n s o l v e r

y (mm)

z ( m )

Ion trajectories compared against SIMION (both existence and absense of space charge)


Parameters : Electron beam energy 12.5 keV, 0.1 A, 1T6T magnetic field

Test of geometrical acceptance with NSCL EBIT

Aim : To confirm NEBIT can provide geometrical acceptance of

complicated system and consistent with analytical formula

-0.3 -0.2 -0.1 0.0 0.1 0.2 0.3

-8

-6

-4

-2

0

2

4

6

8

ax (mrad)

x (mm)

-0.3 -0.2 -0.1 0.0 0.1 0.2 0.3

-8

-6

-4

-2

0

2

4

6

8

ax (mrad)

x (mm)

-0.3 -0.2 -0.1 0.0 0.1 0.2 0.3

-8

-6

-4

-2

0

2

4

6

8

ax (mrad)

x (mm)

▪ 1T6T-1T▪ 1T6T-6T▪ 6T6T


Parameters : Electron beam energy 12.5 keV, 0.1 A, 1T6T magnetic field

-0.3 -0.2 -0.1 0.0 0.1 0.2 0.3

-8

-6

-4

-2

0

2

4

6

8

ax (mrad)

x (mm)

-0.3 -0.2 -0.1 0.0 0.1 0.2 0.3

-8

-6

-4

-2

0

2

4

6

8

ax (mrad)

x (mm)

-0.3 -0.2 -0.1 0.0 0.1 0.2 0.3

-8

-6

-4

-2

0

2

4

6

8

ax (mrad)

x (mm)

▪ 1T6T-1T▪ 1T6T-6T▪ 6T6T

Test of geometrical acceptance with NSCL EBIT

Aim : To confirm NEBIT can provide geometrical acceptance of

complicated system and consistent with analytical formula

Calculationacceptance (pi mmmrad)

NEBIT FW formula %error

0.1 A 1T6T-1T 1.47 1.5 -2.0

1T6T-6T 0.65 0.68 -4.4

6T6T 0.64 0.68 -5.9

NEBIT calculates the geometrical acceptance consistent with analytical formula

Check of capture probability


• NEBIT provides 57.49 % @ 3 πmm mrad

• 14% are ionized before the first barrier

• ~8.5% lost in the trap

Aim : Compare the capture probability from NEBIT and a combination of

geometrical acceptance and ionization cross section

Condition : Ion is flying through constant

magnetic and space charge fields.

Geometrical

acceptance

Ionization

probability

Capture probability vs emittance


RIB

Q/A-separator

EBIT

RFQ

Reaccelerator concept for rare isotope beam

+ Single electron impact ionization (∼10 µs for 1+→2+)

- Radiative recombination (∼10 ms)

- Charge exchange between ions-neutral atoms (∼100 ms)

• Ion heating by electron beam (10 ms – 10 s)

• Ion-ion energy exchange (∼1 ms)

Charge evolution and ion dynamics


; σ( Ee , IA )

; σ( Ee , qA )

; σ( qA , IB )

; R( Ee , Mi )

; R( Mj, Mi )

For the acceptance calculation, only the electron impact ionization is considered

Time scale for a current density 4x104 A/cm2

Energy spread and radial energy


19.980 19.985 19.990 19.995 20.000

2nd potential barrier (kV)

1st derivative of

current (pA/kV)

19.980 19.985 19.990 19.995 20.000

0

200

400

Current (pA)

Beam energy 19.99 keV with FWHM 2 eV

CollectorElectron

gunFaraday

cupBOB1

Potential barrier

Aim : Minimize the radial energy to increase overlap fraction

Trap potential Potential

barrier

Faraday

cup

0.01 0.1 1 10

1E-5

1E-4

1E-3

0.01

0.1

1

10

100

K9+

K19+

EI Cross section (cm

2)

Electron beam energy (keV)

x10-17

K1+

Electron impact ionization

Breeding time :

For je = 667 A/cm2 ,

Ee = 19.5 keV, σ = 9.24 x 10-18 cm2

t1�2 = 16.2 µµµµs

; σ( Ee , IA )

cross section of potassium

Ionization

energy

Electron

energy>


Charge state and breeding time



Trap

entrance

Inner

barrier

0 50 100 150 200 250 300

-4

-6

-8

-10

-12

-14

-16

-18

-20

-22

Voltage (mV)

Time (µs)

Bottom deflector electrode

Upper deflector electrode

Injection

voltagesExtraction

voltage

Time


Reproduction of TOF spectrum of ion reflection

Ideal expectation with

2 reflection regions

Problem of electronic device figured out by TOF spectra

Comparison of NEBIT Predictions with CBSIM

K. Kittimanapun

Parameters :

Electron beam energy 12.5 keV, 1A

electron beam currents, Fe-beam,

6T6T magnetic field

Charge evolution calculated from two different approaches;

CBSIM : Rate equation with semi-empirical EI cross section

NEBIT : Monte-Carlo based ion trajectory calculation

NEBIT provides charge state

evolution consistent with CBSIM

Slide 49

Charge state evolution

Optimal breeding time for Fe15+ :

CBSIM = 0.4 ms, NEBIT = 0.6 ms

Emittance measurement

0 50 100 150

0

5

10

Row Numbers

Intensity

0 50 100 150

0

5

10

15

Row Numbers

Method:

• Capture beam images with different potential applied to a quadrupole

• Extract beam sizes (1σ) from Gaussian fit

• Obtain transfer matrix from SIMION

• Extract emittance from fitting beam size with transfer matrix elements

Triplet


K+

K. Kittimanapun

1000 1200 1400 1600 1800 2000 2200 2400

0

5

10

15

20

25

x2,y

2 (mm

2)

Quadtrupole Voltage (V)

εx = 5.5 ± 0.1 πmm⋅mrad

εy = 3.7 ± 0.4 πmm⋅mrad

Emittance fit

Quadrupole C

Emittance measurement

2500 2600 2700 2800 2900 3000 3100 3200

0.6

0.8

1.0

1.2

1.4

y2 (mm

2)

x2 (mm

2)

Voltage (V)

0

4

8

12

16

20

600 900 1200 1500 1800 2100 2400

0

2

4

6

8

Horizontal axis

x2, y2 (mm

2)

Voltage (V)

Vertical axis

εx = 1.4 πmm⋅mrad

εy = 4.5 ± 0.4 πmm⋅mrad

Quadrupole AQuadrupole B

• Emittance cannot be fitted for

quadrupole B

• Beam diameter is large at quadrupole B

• Emittance ranges 1.4 – 5.5 π mm⋅mrad

Slide 51

K. Kittimanapun


Slide 52

Capture efficiency vs trap size

Larger trap size leads to → Longer traveling time

→ Higher ionization probability for 1+ → 2+ charge state

→ higher capture efficiency

Different trap sizes obtained by adjusting trap potential

1.4 π mm⋅mrad

5.5 π mm⋅mrad

Experimental setup


Test ion source

Produce K+ beam of 20 keV via

surface ionization process

Q/A separator

• ion and charge state selection

• 2 electrostatic benders and 1

bending magnet

• Q/A acceptance 0.2 - 0.5

• Acceptance ~120 ππππmm⋅⋅⋅⋅mrad for a

beam of 12 keV/n

M. Portillo et al., Proceeding of PAC09

Diagnostic devices at BOBs

MCP Faraday

cup

Image a beam and

detect the TOF signal

Monitor ion beam

electric current



Trap entrance

(LTC11 )Inner barrier (LTE4)

With this technique,

• Two returning locations : inner barrier and trap

entrance

• By monitoring ion current with FC, more than 95 %

of detected beam reached the EBIT trap center

1+

LTRAP LTE1

MCP signal vs time-of flight

Determination of Trap Capacity

0 500 1000 1500 2000

0

10

20

30

40

50

60

70

80

Injected beam current (pA)

Beam current of K

16+

10 100 1000

2.0

2.5

3.0

3.5

4.0

4.5

Charge breeing efficiency into K

16+

Injected beam current (pA)

x10-3

• Efficiency depends on incoming beam current• With Ie =135 mA, Ee = 19.5 keV, Ltrap = 0.637 m → Charge capacity ∼1nC ⇔ 1 nA

• Efficiency of K16+ = 2.4 x 10-3 for 1.4 nA incoming beam

• Capture efficiency drop by a factor of 1.5


K16+ current vs Injected beam current Charge breeding efficiency of K16+ vs injected current

(pA

)

Ch

arg

e b

ree

din

g e

ffic

ien

cy i

nto

K1

6+

(%)

X 10-1

Experimental setup


2T2T magnetic field configuration

19.5 keV electron beam energy

New approach to determine effective

space charge potential

With electron beam of 90 mA and 19.5 keV:

� Total potential becomes lower

� ions travel faster

� Change in TOF signal allows determination

of space-charge potential affecting to K+


• Electron beam is not uniformly distributed over its

cross section (more details later)

• Effective space charge potential on K+ is ~20 V

Vo

lta

ge

(m

V) Without e-beam

Vo

lta

ge

(m

V)

Vo

lta

ge

(m

V)

1+Without

e-beam

With e-beam

1: trap entrance, 3: trap end

2: area between trap entrance and end

With 90 mA e-beam

Space charge affects to ion trajectory

With 25 mA e-beam


• Electron gun has been modified and is able to

provide 800 mA

• Electron beam radius was measured and

larger than expected

• EBIT has reached a 30% capture efficiency

– EBIT is a suitable charge breeder for ReA

• Working towards higher current and current

density

Present status and EBIT outlook


Documents

Investigation of ion capture in an Electron Beam Ion Trap ......Study ion reflection with time-of-flight spectra Intuitively determine ion reflection region Maximize the transport