ECR Ion Source Operations

ECR Ion Source Operations

Janilee Benitez

Lawrence Berkeley National Lab

March 4, 2020

Outline

1. 88-Inch Facility Layout

2. Intro to ECRs

3. Cocktail Beams

4. Availability & Reliability

5. Resources to Support Chip Testing and SHE

AECR-U aluminum

plasma chamber

Cyclotron Facility Layout

Janilee Benitez Operations Review March 4, 2020

Cyclotron

The 88-Inch Cyclotron is fed by three ECR ion sources: ECR, AECR-U, and VENUS.

Cave 4A Light

Ion Facility

Cave 4B Heavy Ion

Facility

ECRVENUS

AECR-U

3

Cave 1 BGS

ECR Ion Source Physics

wave

e

ECR

m

Be−

=⋅

µω

Sextupole Magnets

(radial confinement field)

Solenoid Magnets

(axial confinement field)

µ-waves

gas

Ion

beam

3

1

2a

2b4

High Voltage

5

1

+

3

+

2a

2b

4

gas

µ-waves

radial field

= +

+

axial field

5

High Voltage

Ion beam

Key Ingredientse-

TBECR

1=GHzwave

28=−µ

ω

ECR: Electron Cyclotron Resonance

Janilee Benitez Operations Review March 4, 2020 4


ECR’s at the 88-Inch

ECR

1983

Max B-Field: 0.4T

Frequencies: 6.4GHz

Max Power: 0.6kW

AECR-U

1996

Max B-Field: 1.7T

Frequencies: 10, 14GHz

Max Power: 2.6kW

VENUS

2004, 2008 for operations

Max B-Field: 4.0T

(superconducting)


Max Power: 12kW

2

RFen ω∝

5


ECR’s at the 88-Inch

ECR

1983

Max B-Field: 0.4T

Frequencies: 6.4GHz

Max Power: 0.6kW

AECR-U

1996

Max B-Field: 1.7T


Max Power: 2.6kW

VENUS

2004, 2008 for operations

Max B-Field: 4.0T

(superconducting)


Max Power: 12kW

6

MARS

(Dan’s Talk)

(Dan’s Talk)

Beams Produced/Accelerated

Gas,

Gaseous

compoundsLow

Temperature

Oven <800°C

High

Temperature

Oven

<2200°C

Tested in Ion

Source/Not

Accelerated

Sputter

Probe

MIVOC: Metal Ions from

Volatile Compounds

C2B10H12


With the right tool we can

produce any beam.


VENUS produces 124Xe43+ for users!

Figure: Carlson T A, Nestor N and Wasserman N 1970 Ornl Report 4562

Require hot electrons to reach high

charge states

σ for producing high charge state is

orders of magnitude lower

VENUS produces 124Xe43+ for users!

For Z=54, to reach a Xe+43 charge state

requires ~5x103eV electrons!

What Makes a Good ECR Source?

8

Cocktails and Chip Testing Super Heavy Elements

Stable beam productionGood source conditions

Long term beam productionGood oven technology

Low consumption of metals

High intensity beamsdensity ∝ heating freqency2

2

RFen ω∝

For both, a good ECR must be followed by a good

accelerator!


VENUS ECR Ion Source

1

10

100

1000

104

4 6 8 10 12 14 16 18

Extr

acte

d b

eam

fro

m t

he

Cyclo

tro

n [

en

A]

MeV/nuc

Xe28+

Xe42+

Xe43+

Xe34+

Xe28+

VENUS

AECR

Beams not available with the AECR

Xe44+

Xe42+

Xe34+

• Currently one of the most powerful ECR ion sources in the world

• Exploring limits of ECR ion sources through R&D

x100!

Beams not available

from AECR

16AMeV

Xe47+

20AMeV

9


Cocktail Beams Development

20MeV/u M/QProduction

Method

LET

(MeV/(mg/

cm2))

RANGE

(µm)

20Ne8+ 2.50 GAS 1.92 548.5

27Al11+ 2.45 GAS 3.25 463.9

78Kr32+ 2.44 GAS 20.9 243.3

89Y36+ 2.47 Sputter Probe 24.2 244.9

109Ag44+ 2.48 Sputter Probe 33.3 226.8

124Xe47+ 2.64 GAS 45.4 193.8

Development of new cocktail ions using VENUS to increase LET and range underway124Xe43+ in 16MeV cocktail: extends LET from 25 to 50MeV/(mg/cm2) now regularly used197Au52+ in 10MeV cocktail: extends LET from 59 to 86MeV/(mg/cm2) now regularly used

124Xe47+ in 20MeV cocktail: also now regularly used!

CNe

AlAr

CuKr Y Ag

Xe

NO

NeSi

ArClV

Cu KrXe

BO

NeSi Ar

V Cu KrY AgXeBi

Au

BN

Ne Si Ar V Cu KrYAgXeTbTaBi

10

100

1000

0.1 1 10 100

Ra

ng

e in

Si (

µm

)

LET 0° (MeV/(mg/cm2))

88-Inch Cyclotron Cocktail Ions

20MeV/u

16MeV/u

10MeV/u

4.5MeV/u

10

Why the need for 20MeV/u cocktail?

• increasing beam energy allows for

deeper penetration into parts

• Layers on chips are increasing in

thickness

Development for higher energy beams to use for

testing in air if this is requested…ex: 25MeV/u78Kr34+


ECR Ion Source Reliability & Availability

Reliability Fail time due to ECRs since 2/2/2017 is 13.5 hrs!

However, this doesn’t mean all ions were always available!

AECR-U & VENUS not one-to-one replacements for each other.

273K

4 Cryocoolers

LHe

11

20MeV/u M/QProduction

Method

LET

(MeV/(mg/

cm2))

RANGE

(µm)

20Ne8+ 2.50 GAS 1.92 548.5

27Al11+ 2.45 GAS 3.25 463.9

78Kr32+ 2.44 GAS 20.9 243.3

89Y36+ 2.47 Sputter Probe 24.2 244.9

109Ag44+ 2.48 Sputter Probe 33.3 226.8

124Xe47+ 2.64 GAS 45.4 193.8

Availability VENUS availability for beam delivery increased:

Cryostat Modification Implemented in 2017 and tested

successfully in 2019. Additional heaters reduced cryocooler

maintenance from ~8 weeks to 1 week!

However, beam development time decreased!

Shutdown development time is hampered by LCW outages

No cyclotron available during shutdowns


Increase reliability for SHEFailure & Consequence Solution

VENUS HiT Oven Failure:

unreliable, no spare shaft

Build a spare HiT

Oven shaft

VENUS Failure:

Low temperature oven run

at AECR with liner, lower

intensity and higher

consumption

Backup to

VENUS: 3rd/4th

generation ion

source

Mitigating Risks

Increase reliability for cocktailsFailure & Consequence Solution

AECR Failure:

No sputter probe metals (Ag,

Y, Ta, Cu, Tb, Si, V)

Sputter probe with

multiple metals at

VENUS

VENUS Failure:

No high charge state Au, Xe,

Kr

Backup to VENUS:

3rd/4th generation

ion source

-V

-V

-V

+

+

++

+

plasma

Au

Ag

Cu

Increase reliability for cocktailsFailure & Consequence Solution

AECR Failure:

No sputter probe metals (Ag,

Y, Ta, Cu, Tb, Si, V)

Sputter probe with

multiple metals at

VENUS

VENUS Failure:

No high charge state Au, Xe,

Kr

Backup to VENUS:

3rd/4th generation

ion source

VENUS high intensity runs:

Difficult to run high charge

state cocktails after

Backup to VENUS:

3rd/4th generation

ion source

12


VENUS’ IntegrationFiscal Year 2007 Fiscal Year 2011

AECR

56.7%

ECR

34.5%

VENUS

8.9%ECR

41.8%

VENUS

1.1%

AECR

57%

ECR

8.9%

VENUS

17.5%

AECR

73.6%

Fiscal Year 2012 Fiscal Year 2016

AECR

60.2%

VENUS

39.8%

13

Trend is increased need

for VENUS beams

Source Use

• To fulfill the needs of the chip testing and research communities,

development of VENUS continues

• With the regular use of VENUS for beam production we have less

time for R&D

• R&D is not only needed to develop 4th generation ECRs but also to

develop beams for chip testing and intense beams

Conclusions


ECR Ion Source Operations

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