EIC'04 Mar 15-17,2004

Overview of Electron Cooling Activities at FNAL

Thomas KrocFermilab – Electron Cooling

EIC 2004March 15-17, 2004

Jefferson Lab

EIC'04 Mar 15-17,2004

Electron Cooling System Parameters Parameter Value Units

Electrostatic Accelerator Terminal Voltage 4.3 MV Electron Beam Current 0.5 A Terminal Voltage Ripple 500 V (FWHM) Cathode Radius 2.5 mm Gun Solenoid Field 600 G

Cooling Section Length 20 m Solenoid Field 150 G Vacuum Pressure 0.1 nTorr Electron Beam Radius 6 mm Beam angular spread ≤ 8 0 µrad

Schematic Layout of the Recycler Electron Cooling

EIC'04 Mar 15-17,2004

Simplified Electrical Schematic of Recirculation

For I=.5A, I=5ABeam Power

2.15 MWPower in current loss

21.5 WPower dissipated in collector 2.5 kW

s Current

ControlElectrode

ElectronBeam

+

4.3 MV

AnodePS

High VoltagePelletronTerminal

+

5 kVCollector

SuppressorElectrode

+

Cathode

Anode

Los

50 kV

Also called Bias Supply

EIC'04 Mar 15-17,2004

Alexey Burov

Longitudinal rates

Both longitudinal and transverse electron cooling of pbars look attractive for the Recycler, especially with vacuum (1-3 pi mm mrad/h) improvements after the last summer shutdown. Figures below are calculated for 0.5 A of the electron current and 0.2 mrad of the effective 1D rms angle of the e-beam.

0.1 1 10 1001 10 3

0.01

0.1

1

10Long Cool Rate 1/hours

norm action, mm mrad

5.502

6.258 103

el II 1 1( ) 3600 el II 1 2( ) 3600

39.9930.117II n 10

4

EIC'04 Mar 15-17,2004

Alexey Burov

Transverse rates

The transverse rate is shown here. Both curves are calculated for norm rms emittance of 1.2 mm mrad. The horizontal axis is the action in mm mrad (averaged action = norm rms emittance) for the longitudinal core (red) and tail (blue) particles. For the bulk of the beam, the e-folding time is 20 min or shorter. The rates are defined as action logarithmic derivatives.

0.1 1 10 1001 10 3

0.01

0.1

1

10Transverse Electron Cooling Rates 1/h

4.037

9.728 103

et II 1 1( ) 3600

et II 1 2( ) 3600

39.9580.117II n 10

4

EIC'04 Mar 15-17,2004

Full Scale Beamline at Wideband

MilestonesMilestonesLow intensity DC beam in collector Jul 03Stable .5A at 3.5 MeV Dec 03Cold Beam at .5A, 3.5 MeV Mar 04

EIC'04 Mar 15-17,2004

RecirculationComparison of 180 U-bend

test with full beam line

2004

2002

Note differentBias CurrentResponse

Difference in Bias current response due to different loss characteristics in line (affecting beam envelope ?)

EIC'04 Mar 15-17,2004

Stability

500 mA, 4.5 hour run3 interuptionsRestored within 12 seconds by FSM

EIC'04 Mar 15-17,2004

Arden Warner

Multiwire Profile data

Overlay of Vertical profiles with a 2mm shift

00.2

0.40.6

0.81

1.21.4

5 10 15 20 25 30 35

wire no.

Vo

lts

Vert profile

Vert profileshifted

Overlay of Horizontal profile with a 2mm shift (SPA05I=12amps)

00.2

0.40.6

0.81

1.21.4

10 15 20 25 30 35

Wire no.V

olt

s

Horz profile

Horz profileshifted

Comparison of profiles that are shifted by 2mm±2% relative variation

EIC'04 Mar 15-17,2004

Gun Schematic

Gun assembly with solenoids

Anode, w/diaphragm

Cathode w/ControlElectrode

EIC'04 Mar 15-17,2004

Vitali Tupikov

-- based on August measurements for Bz=100G --

Bx0, Bx0’ (G)

By0, By0’ (G)

dBxy0 (G)

Bxy0’ = Bxy0 + <dAlfa(SPCn)>*Bz + <dBeta(SPCn)>

Z (m)

Field Maps of Cooling Section

EIC'04 Mar 15-17,2004

Drawing of a Cooling Module

EIC'04 Mar 15-17,2004

Alexander Shemyakin

Angles in the Cooling Section

The best RMS values, in mrad. The goal is 0.08 mrad for each.

Value

Comments

Central trajectory 0.3

0.2

Without CS field correctionsWith field corrections

Boundary electron with respect to the center

0.6 I = 0.35 A, Bcs=100G, beam diameter 9 mm

Trajectory oscillations and drift

0.1 0.2?

I = 0.17 A, 3 Hz- 1 kHzIn a shift> 1 kHz

EIC'04 Mar 15-17,2004

Alexander Shemyakin

Beam OscillationsA program records readings from a single BPM channel with 3 kHz rateThe largest component in the most of signals is 30 Hz (29.6 Hz), and the next is 60 Hz30 Hz component is the largest one in the CPO (Pelletron voltage) signal as wellThe beam oscillations may be originated by terminal mechanical motion, oscillations of HV, fields from motors and power grid, …

-0.3

-0.1

0.1

0.3

0 50 100

Time, ms

BP

M r

ea

din

gs

, m

m

XA01

YA01

-0.3

-0.1

0.1

0.3

0 50 100

Time, ms

BP

M r

ea

din

gs

, m

m

XC01

YC01

-0.3

-0.1

0.1

0.3

0 50 100

Time, ms

BP

M r

ea

din

gs

, m

m

XR05

YR05

EIC'04 Mar 15-17,2004

Alexander Shemyakin

Diagnostics

Wire scanner BPM Scraper Flying wire Multiwire

EIC'04 Mar 15-17,2004

Magnetic Shielding

MI Ramp ~ .5 HzFields due to busses, Q306

EIC'04 Mar 15-17,2004

Main InjectorBeamline

Main InjectorQuad

EIC'04 Mar 15-17,2004

Bus Configuration

Triquad bus3 parallel bussesCenter full current2 returns – half currentDipole and quad busQuad compensation loop

Existing dipoleonly

New dipoleand quadpositions

EIC'04 Mar 15-17,2004

Magnetic Shielding

Tested two shieldsTelescoping “trombone”2 halves2 orientations

stray field in e-cool return line, IQB320-1measured above magnet body, y=6.625"

-1.00

-0.80

-0.60

-0.40

-0.20

0.00

0.20

0.40

0.60

0.80

1.00

0.0 500.0 1000.0 1500.0 2000.0 2500.0 3000.0 3500.0 4000.0 4500.0

current, A

B, g

auss

B_x "trombone" pipe - 340

B_x clamshell - horizontal seam - 128

B_x clamshell - vertical seam - 51

B_x unshielded

EIC'04 Mar 15-17,2004

Integrated Fields

EIC'04 Mar 15-17,2004

To Do List:

High LossesGun lifetimeBeam MotionDriftsConditioning4.3 MeV

Magnetic ShieldingEnergy Cal.Detection of Cooling

EIC'04 Mar 15-17,2004

Schedule

Now – cold beam (not yet)4/20/04 – new enclosure complete6/1/04 – disassemble Pelletron, begin move8/23 – 11/19 – shutdown for tunnel installation, resume reassembly3/1/05 – commission Pelletron5/1/05 – commission ecool12/1/05 – Electron Cooling Operational

EIC'04 Mar 15-17,2004

Sergei Nagaitsev

Commissioning stages

HV commissioning of the Pelletron (1 month)U-bend recirculation (1 month)Full beam line (4 month) Pulsed beam DC beam

Pbar – electron beam: position matching (1 month)Energy matching (1 month)Cooling rate measurementsElectron beam optimization