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Linac4 H- source:

Status & objectives

tbc.drawing SPLNFHR … _ D E F G H

units produced : DESY SLHC IS01 IS02

IS03protons+ Magn.

IS04 Tilted Magn.

Frontend, supportPumping port

o 2 - - -

Main insulator o 2 x xExtraction optics o 2 x x xPlasma Generator 1 o 2 2 1Flange o 2 2 + x x xRF-Transfo-Matching o o 2 - - Handling-gear o 1 x xCs-condenser x

IS-test stand 152 o 1LEBT o 1Photometry Spectroscopy 1 1RF-Amplifier 100kW 50Hz 1L4 faraday cage 400 1LEBT 1RF-Amplifier 100kW 2Hz 1Pumping system o 2RGA 1 1Pulsed HV + cw Einzel 2Arc Discharge x xH2-distribution IS+LEBT 2Cs-Oven 2 x xCs-test stand 357 Optics TS HV + Piezo 1Tools: Prod., storage 1 1 1 x xMag-meas. Unit 6 1

o : obsoletex : mandatory work

Partially/not yet designedProduced but Failed

L4-IS

40

0An

cilla

ries

Produced and sucessfully testedProduced being tested

IS-T

S15

2L4-ISWP

Desig

n / E

ng. /

Pro

d.

April 2014

Nov. 2013 ISWP-Review: Report available Apr. 2014: 1) ISWP met essential deadlines.2) Probability of H-beam within

nom. emitance.

3) Recommend to set equal effort on Cesiated surface and magnetron H- sources

H- beam IS02 Magnetron

40 mA 90 % 95 %

60 mA 40 % 80 %

80 mA 5-10 % 65 %

Tilted Magnetron WP: Budget request launched

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Tests prior installation of Cesiated IS02 in L4 Date

test Nr.

Plasma Generator

Extraction optics

Cesiation conditions Goal/result of the measurement

Hardware specificities

Sep-13 5 L4 Desy IS-01 uncesiatedlimited to 20 kW RF power: Stable production from sept 2013 to March 2014

Dec-13 6 TS IS-02 IS-01 uncesiated Validation of the volume mode PIC beam formation simulation from S.M. 2012

4 turns sol. AntennaO-ring seals on the PG

Dec-13single ~0.2 mg

single ~1 mg

Validation of the Cs-surface mode PIC beam formation simulation from S.M. 2012Test at 100 kW RF power Ok. max beam of H- : 60 mA

Jan-14 7 TS IS-02 IS-01Recovery of a 2 weeks pumping stopCs-dynamics after single Cs-deposition

O-ring seals on the PG

Feb-14 8 TS IS-02 IS-01 single ~5 mg

Stabilization at 35-40 mA 2 weeks Space charge compensation in the LEBTSlow ramp up (2-3 days) to e/h=1-2, then stable for 6 weeks at 30 kW RF > 35 mA+ Cs-dynamics

Apr-14 9 TS IS-01 IS-01 uncesiatedTest of H- volume production with shaped plasma electrode (grounded): with cusp magnets + emittance

4 turns sol. antenna, shaped pl-el.

Apr-14 10 TS IS-01 IS-01 uncesiated H3-H2-p-mode intensity + emittance

May-14 11 L4IS-01Desy

IS-01 uncesiatedDepending on test resuts:Operation in L4 12 or 20-25 mA

May-14 12 TS IS-01 IS-01 uncesiated H- volume production without Cusp magnets

Jun-14 13 TS IS-02 IS-015mg Cs + vented

Test of recovery of a cesiated ion source that was vented during O(1) hour

Jul-14 14 TS IS-02 IS-01-02 uncesiated test of 2nd prototype and new optics New optics

Aug-14 15 L4 IS-02 IS-02 uncesiatedinstallation of 2nd prototype in the tunnel + test in vol-mode. Validation of d-base acquisition

4 turns sol. AntennaMetal seals on the PG

Sep-14 16 L4 IS-02 IS-02 single ~5 mg nominal operation of 2nd prototype in the tunnelSep-14 17 TS IS-01 IS-01 uncesiated H3-H2-p-mode intensity + emittance New p-optics

First cesiated source (IS02) operation Nov. 2013 - Apr. 2014

3

RF C

ondi

tioni

ng

Xmas

stop

HV-m

odif.

Cesia

tion

1&2

0.2

& 1

mg

Cs

Cesia

tion

35

mg

Cs

Volu

me

prod

.

Logbook data

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IS02 Accumulated experience in conditioning & H- Production:

Plasma Generator cond.: 10 days Volume production: 30 days Cesiated surface: 80 days

D-base operational

Notes on IS02: Volume production

30 mA Cesiated 60 mA Cs-shortage: Strong

anti-correlation between H- current and e-current

Improvement of e/H few hours after cesiation

Holds 100 kW RF

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Database input via OASIS

A standardized OASIS menu fixed scalingand insertion of units and physical scaling factors leads to the observable (voltage current, pressure temp. power).

6

Monitoring & tuning tool:

50 kW RF

-35 mA H-

Plasma light

Pulsed HV

LLRF-power

Improvement of the RFFeed back loop

Is our next challenge

6 weeks int. operation after the 3rd cesiation

Exch

ange

HV-

tran

sfo e measurements

Regulation tests

Puller HV trip: H- beam drops to 5-10 mA.

H- beam between 27 and 45 mA. Overall beam availability 61% (47 days period), Average 33.2 mA H-

High voltage Overall availability: source & dump HVs: 87% (47 days period), Availability Puller HV: 78% mandatory reset after over current.

RF Overall availability: RF: 83% (47 days period),

Daily tuning of the cesiated source Few days of optimum operation, Daily source-HV trips: An auto restart is needed.

O(10 mg) cesiation

cesia

tion

Plas

ma

cond

ition

ning

Recuperation of the Cs-surface production

Exch

ange

HV-

tran

sfo

The I-source signal is proportional to the scale of the OASIS viewer !We have to freeze the scales to secure the Dbase.

After 1 week interruption under high vacuum IS-02 restarts in volume mode, half a day of continuous operation is needed to switch back to Cs-surface productionmonitored via the e/H ratio.

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Histograms of observables i.e I-Puller and Beam energy

-44970±20V

Std. Dev: 150±25V

45.5±15mA

46±1.5 mA

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DB-correlations

Puller: 4.6 mA/kW

F. cup: -1.4 mA/kW

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Proton, H2+, H3

+ source

IS01 PG+45 kV

Puller 35 kV Einzel lens -35 kV

Boundary: compatible with existing front end.

Iteration between design and beam simulation on-going

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Magnetron: BNL-test Post mortem, Status and outlook

Molten W-tip

Heated Anode body mandatory for 0.8Hz operation designed and ready for production

W-tip and broken isulator ceramics will be replaced.

2 stage extraction: Puller at 30 kV

https://edms.cern.ch/document/1352150/1

Modification of the Is-Front end: Large ceramic insulatorDelivery: Ceramic insulator: March-April 2015Deep flange

Mtl. End Nov, Machining end January 2015

Today’s Front end

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Procedures: i.e. Exchange of a cesiated source

Action duration Result Safety equipment check 1’ Lab coat: Op1 … Op2 …

Goggles: Op1 … Op2 … Gloves: Op1 … Op2 … Eye washing bag

OP1: Switch off all equipment: ignition, solenoid & Heating systems. Systematic consignation RF, HV and grounding of the equipment. Manual closing of H2 tank and supply valve.

10’ Consigné and ready for access.

Venting the vacuum system 10’ Filled with N2 Removal of RF-transformer 10’ Removal all cabling incl. HV 30’ Disconnecting the H2 line + packing in Al foil

10’

Removal of Cs-heating jackets 10’ Good access to Cs-Oven Removal Cs-Oven + closing both sides of the connection with clean plugs and colliers + Al-foil packing.

10’ For this point safety equipment mandatory

Transport Cs-Oven to Cs-lab. 10’ Cs-Oven stored in Cs-lab. Removal of PG housing and movement of the cable tray.

10’ Nothing preventing transport through the roof.

Removal of the roof 20’ Ready for transport. Dismount Flange Take Pictures Protect Flange with Al foil

20’ From this point safety equipment mandatory

Take Pictures front end Protect Front end with Al foil

20’ From this point safety equipment mandatory

Move flange + PG into storage box 10’ Flange + PG secured. (no risks of Cs contamination)

Install new Flange + PG. 30’ Potential Cs-contamination of the Front end confined; All waste in a dedicated plastic bag.

Date: …………………………….Op1: Leads mechanical tasks, handlingOp2: Vacuum operation, HandlingOp3: Prepares specific tools,

Op4:

Organization ad safety: Ensures follows up of the procedure, written proceedings, and safety.

IS-test stand: preparation 3h, operation 2h, Restart 5h + 1 night

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Post mortem of IS02

Findings: Damaged HV-feedthrough Coloration of the HV ceramic insulators

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Conclusion summary First 2 month operation of a cesiated source at CERN is a very positive

sign. However; IS02 PG+IS01 optics dumps the beam on the wrong electrode. Good enough to

measure e/H, less for operation. On-going design of an optics for e/H of 2 to 8. Installing Cs-heating in L4: July 2014

After 2 month and ~12 mg Cs a yellowish layer is seen on all insulators. New ceramics insulator should provide additional space for Cs-

condenser, only available by 2015. Next: calibrated IS-DB in Linac4 Installing IS02 with IS01 optics in L4 requires later modification of the

optics; Preferably Minimize number of installations: install IS02 only in august. Consider discussing the installation of IS01 instead of Desy if satisfactory results

are available by beginning of May 2014Invaluable inputs from the IS-team is thankfully acknowledged

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Nov. 2013 ISWP-Review mandate

The second review of the Linac4 ion source work package took place at CERN on November 14, 15 2013. The review committee was asked to assess the following three items:1) Review of the Linac4 ion source Work Package; Compare what has

been achieved with respect to what was planned and review what is foreseen.

2) Estimate the probability of having a sufficient beam current (40, 60, 80 mA) within the design emittance of 0.25 ·mm·mrad in time for the final commissioning before the connection (February 2016).

3) Is it still necessary to pursue an alternative solution, and is the magnetron source still considered as the most appropriate option? When a decision has to be made and what has to be prepared to make such a source available on-time for the final commissioning of Linac4?

3rd Cesiation: Stable datasets: 54%

3rd cesiation 170 deg.Cesiation 200 nm O(5 mg) 12-Feb-14Emittance measuremnt campaign (H2 in LEBT) 13-Feb-14RF-fault grid bias, plasma oscillations at restart 17-Feb-14

18-Feb-14good emittance day 19-Feb-14N2 in LEBT 20-Feb-14

21-Feb-14Kr in LEBT 25-Feb-14

26-Feb-14H2 in LEBT (observation of RF noise induced in the piezo signal) 27-Feb-14Retuning of Source, FBL off cw:15VT-correlation over WE 28-Feb-14Effect of SolenoidEmittance meas. @ 44mA 03-Mar-14Short time evolution of current after LEBT pressure setting change 04-Mar-14Effect of p(LEBT) on FC current 05-Mar-14With/wo einzel and sol at 120 A 06-Mar-14FBL on: density regulation stopped 2:30 (soon followed by puller stop) 07-Mar-14

10-Mar-1411-Mar-14

FBL and Density regulation off 12-Mar-1413-Mar-14

Space charge compensations studies Hydrogen regulations studies

Next: IS02 Stability above 40 mA Complete DAQ Handling/Storage of a cesiated source Operation of IS01 in volume mode Restart of a cesiated source after storage

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Cs-Oven