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OPPIS with neutral H injector layout. Atomic H injector Neutralizer cell He-ionizer cell Rb-cell Na-jet cell H+H+ H0H0 H+H+ H0H0 H-H- H2 HeRbNa TMP1 CP1
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Polarized source upgrade
RSC, January 11, 2013
OPPIS
LINAC
Booster
AGS
RHIC
(2.0-2.2) 10∙ 11 p/bunch
0.6mA x 300us→11 10∙ 11 polarized H- /pulse.
(6.0-6.5) 10∙ 11 polarized H- /pulse at 200 MeV
(2.2-2.4) 10∙ 11 protons /pulse at 2.3 GeV
~1.8∙1011 p/bunch, P~60-65% at 100 GeV P ~ 56% at 250 GeV
RHIC Polarized beam in Run 2012
OPPIS with neutral H injector layout.
Atomic H injector
Neutralizer cell
He-ionizercell Rb-cell
Na-jetcell
H+ H0 H+ H0 H-H2 He Rb Na
TMP1CP1
The FABS and new SCS at operational OPPIS bench.
The FABS and new SCS at operational OPPIS bench
“Fast Atomic Beam Source”, BINP 2011
Plasmatron 4-grid protonextraction system
H2 Neutralization cell
~ 3.5 AequivalentH0 beam
FABS produces 200-300 mA equivalent H0 beam intensityWithin the Na-jet ionizer acceptance.
Residual un-polarized H0 beam component suppression by the energy separation.
H+(70%)
H0(7 keV)
H0(3.0keV)
-4.0 kV-4.1 kV -4.1 kV
H0(7.0keV)
He-ionizer cell Rb -cell
H0(30%)
DecelerationH0 + He → H+ + He + e
-2-3 kV +0.1kV
Polarization dilution in the FABS.
H0 (7 keV)
H+ (7 keV)
H+ (3.0keV)
H0 (3.0keV)
H- (3.0keV)
H- (35keV)
Ionization in He-cell~70%
Neutralization in Rb, ~70%
Na-jet, 8.0%
Polarized ~ 4.0 %
H0(7 keV) H-(7 keV) H-(39 keV)40% 2%
H+ (7 keV)H2-cell
0.8 / 4.0 ~ 20% - polarization dilution.4.0 keV energy separation would allow dilution reduction to less than 0.5%.
Losses at Deceleration, ΔE = - 4.0 keV, ???
Acceleration - 32 keV
95%
Un-polarized ~ 0.8 %
He-ionizer cell assembly with electro-dynamic valve and proton deceleration system.
Electro-dynamic valve
Three-gridEnergy-separationsystem
He-ionizer cell assembly with electro-dynamic valve and proton deceleration system.
Grid heater to reduce Rb deposition
Electro-dynamic valve operation principle.
Electro-dynamic valve .
Force to the conducting plate in the (high ~ 3 T) magnetic field.
For I=100 A, L=5 cm, F=15 N).
Electro-dynamic valve.
1 – body, 2 – current vacuum feed-through, 3 – gas supply, 4 – flexible springing plate, 5 – “O” -ring.
Changes in the Low Energy Beam Transport Line.
EL2-replaced with the Quad doublet
Variable collimatorIn DB2 to improveEnergy resolution.
New FC
The LEBT is tuned for 35 keV beamEnergy transport.
Energy separation of decelerated (“polarized”) H- ion beam in LEBT.
0
0.5
1
1.5
2
2.5
3
3.5
20 22 24 26 28 30 32 34 36
Acceleration voltage, kV
H- i
on b
eam
cur
rent
, m
A31.5 + (7.5 – 4.0) = 35 keV
I (He-”on”)/ I(He –”off”) ~50
535 uA in FC after RFQ, Rb-91 deg. I=200 A
Energy separated beam vs. Rb –cell temperature
0
200
400
600
800
1000
1200
1400
1600
0 20 40 60 80 100 120 140
T Rb, C
FC4,
mkA
30 uA- He-off
1400 uA- He-cell“on”
31.5 + (7.5-4.0)= 35 keVE0 =7.5 keV ΔE=4.0 kV
FC4, uA
Beam production and transport vs. Rb-temperature at different primary beam intensities.
Rb-91 deg, T9-current-525 uA, I=200A
T9-current-600 uA, Rb-96 deg, I=200 A,
Superconducting Solenoid Sona transition
Ionizersolenoid
LargeCorrectionCoil
OPPIS magnetic field, Sona-transition field shape control.
InternalCorrection Coils
Higher residual field with the new solenoid. Use of iron shield and four correction coils allowed of field
gradients control to the required level.Still there is a room for improvements.
80 %
Laser system upgrade. New wavelength meter.
Optical pumping of Rb-85 (72.7%), Rb-87(27.8%) natural
mixture..Effective width of Rb 85-87 natural mixture including hyperfine Splitting and Doppler broadening is ~ 3.2 GHz
Δν ~ 8 GHz
Laser frequency scan. 200 MeV polarization vs. laser frequency.
~ 12 GHz
Spin “up”
Spin “down”
Dec.16, T9-current 220 uA, Pol-78.7+/-0.7%
Polarization vs. Rb –temperature.
90 deg
80 %
Polarization measurements in Lamb-shift polarimeter.
Rb-cell vapor thickness
OPPIS current and polarization vs. Rb –cell vapor thickness.
5∙1013
Rb-cell thickness, atoms/cm^2
X 1013
Higher ~105 deg Rb cell temperature
Recent progress.• The new solenoid works well.• Both atomic H sources are in operation. Plasmatron operation is quite
stable and reliable. • High –intensity H- ion beam production, acceleration to 35 keV,
transportation in LEBT were studied.• 4 mA H- ion beam was obtained out of Linac.• He-ionizer cell works well with a new pulsed magneto-dynamic He gas
valve. • Reliable deceleration of proton beam was demonstrated.• Very good beam energy separation (Suppression of the “wrong” energy
un-polarized beam component) was demonstrated.• A 600-800 uA energy separated H- ion beam was produced for injection to
RFQ. • Beam polarization measurement are in progress in 200 MeV polarimeter.• 75-80 % polarization was obtained so far.
Recent tests at 200 MeV.
• Goals:• Reliability studies.• Polarization and intensity optimization.• MCR operator training.
Reliable operation
Intensity
Polarization
Results so far.
• Reliable long-term ∙operation of the source was demonstrated.• Very good suppression of un-polarized beam component was demonstrated.• Small beam emittance (after collimation for energy separation) and high
transmission to 200 MeV.• 500-600 uA beam intensity was obtained at 200 MeV (9.0-10.8) ∙1011 H-/pulse at Rb –vapor thicknes ~6 ∙10 13 atoms/cm2, (90 deg. cell temperature).~ 78-80% polarization was measured in 200 MeV polarimeter at beam intensity
200-250 uA.~ 80-82% polarization at 150 uA.~ 74-76% at intensity 300-500 uA. After a new set of magnetic field measurements the Rb-cell position was moved ~ 100 mm upstream in a field flattop part. Hopefully, it will improve
polarization.
Summary
It looks like the source reliability is acceptable for the use in the RHIC Run 13.
The beam intensity and polarization is comparable with the best ECR-based OPPIS operation.
Beam intensity of ~10 ∙1011 was obtained (Booster input).
Polarization measurements and optimization will be continued. There is a room for improvements.
LINAC (T9) H- beam current 4.0 mA at 200 MeVE inj = 4 + 31 kV=35 keV, May 14, 2012.
4.0/0.03 ~33 Suppressionfactor for Un-polarized beam component
4.0 mA
Linac current vs. Rb vapor thickness.
400 uA at 200 MeV7.4∙1011 H- /pulseat Rb thickness13∙1013 Rb/cm2
Ratio of the target to the emitter current density vs spherical grids focal length.
Fig. 8. Ratio of the target current to the emitter current vs focal distance: 1 – without magnetic field, 2 – with magnetic field.
5A, H+ → 200mA, H0→ 16 mA, H-