Ion Source and LEBT Statuses L. Prost (with many contributions from others) Project X Technical Meeting July 3, 2012

Ion Source

Current vacuum chamber not adequate for optics design –Solenoid ends up inside –Need to design a new box and/or modify optics Last report: Source vacuum chamber ‘issue’ Page 3 Ground electrode Solenoid yoke Vacuum port Steering magnet 40 cm

Current solution being investigated Twofold: –Moved solenoid downstream by 9 cm Adjusted optics Moving further downstream makes the beam too large (non- linearities of the magnetic field) –Design a new vacuum chamber (shorter) Impact vacuum and subsequently pumping requirements Try to keep the same differential pumping scheme Page 4 Beam Plasma chamber Ground electrode Vacuum pump 30.7 cm A. Chen

Source equipment procured (unchanged) Source assembly –Ion source –Vacuum chamber** All power supplies: –Steering magnets (20V/10A) Kepco –Bias i.e. source body(-40kV/50mA) Berkeley –Filament (10V/500A) TDK Lambda –Plasma electrode (12.5V/60A) TDK Lambda –Arc (150V/66A) TDK Berkeley –Extraction electrode (5kV/120mA) Glassman Page 5

LEBT

(New) Optics design Page 7 Chose to move ahead with 3-solenoid scheme as the final layout design –i.e. transport without (or little) space charge compensation after bending dipole magnet Fully neutralized (or close) before –Interesting for study/accelerator R&D Increased bending angle from 20° to 30° –Needed to avoid interferences between solenoids when 2 ion sources would be used Not an issue for PXIE but imperative for Px Updated optics for the longer drift at the beginning –Compromise with making the ion source vacuum chamber shorter –Increased from 22 cm to 35 cm Not finalized; more iterations with vacuum chamber design and interface with rest of LEBT (mainly, solenoid #1) Increased drift after 1 st solenoid to accommodate emittance scanner –May need more

8 Size projections (6/15/12) Two rms envelope with B 1  3 = 3.12, 4.12 and 4.69 kG (L lens = 12 cm) 30° bending angle (bending radius 30 cm) Close to rectangular magnet Neutralized section after bend increased 2 cm NeutralizedUn-neutralized 35 cm43 cm22 cm10 cm21 cm18 cm Absorber 12 cm cm10 cm Sol 1Sol 2Sol 3Kicker 1 st vane tip Bend 2.2 m

9 ‘Realistic’ mechanical layout derived from optics file At this stage, not everything fits To scale (except gate valve transverse dimension) 3” beam tube except in the dipole magnet and a small section after the absorber where it is 1.5” 20 cm

10 Emittance growth Emittance growth due to space charge –One ‘topic’ that PXIE can investigate –Preliminary simulations (particle tracking with space charge and spherical aberrations) show that the emittance growth should be acceptable Does depend on the chosen optics FRS:  < 0.25  m (normalized, rms) NeutralizedUn-neutralized V. Lebedev z, cm Beam sizes (1  ), cm Emittance (normalized, rms),  m Note: Example not exactly the current design

Vacuum calculations (preliminary) Page 11 A. Chen Assumes ion source ‘re- designed’ vacuum chamber as shown on previous slides

Vacuum calculations – Additional notes Large gas load from the ion source Calculations assume –1 turbo pump (900 l/s) on the upstream port of the IS vacuum chamber 2 ports available as currently re-designed –2 turbo pumps (900 l/s each) on the downstream port of the IS vacuum chamber 4 ports available as currently re-designed Calculations with beam (10 mA) on absorber –Integrated pressure downstream of the IS vacuum chamber to RFQ entrance: 9  torr ∙ m Single electron charge transfer cross-section 7  cm 2 at 30 keV (JAEA Atomic and Nuclear data tables, 1987)  2% beam loss –Many more losses near the extraction region Page 12

LEBT-RFQ interface Page 13 Stainless steel flange –Hole ID matches RFQ entrance aperture ID = 10 mm Integrate insertion device to design? –i.e. isolated diaphragm RFQ flange ∅ 10 mm >12.5 mm 12 mm Matthew Hoff (LBL)

Instrumentation – Emittance scanner Page 14 Highest priority –Water-cooler Allison scanners (2) from SNS (custom-built) –Fermilab designs vacuum chamber Issues –Heat load on slits (power density might be very high and needs to be controlled) –Space requirements –Solenoid fringe fields Emittance scanner ~100 G BzBz Beam size SNS design V. Scarpine, 07/02/2012

Instrumentation - DCCT Page 15 Base PXIE LEBT DCCT on Recycler design –Three cores  ~1 MHz Two cores for DC and one for AC separated by a ceramic break AC core can be affected by DC cores –Therefore need space between cores  ~ 5” for three cores DC cores AC core Ceramic break Limited space available –Only two cores ? DC  ~1 kHz Recyler DCCT V. Scarpine, 07/02/2012 M. Wendt, V. Scarpine, A. Ibrahim, J. Crisp

Solenoid Emittance scanner Vacuum box Faraday cup Chopper Ion Source Frame to support the vacuum box Q. Ji, 06/29/2012 Chopper Simulation Benchmark Experimental Setup at LBL (with solenoid)

Chopper Simulation Benchmark Experiment at LBL - Status Hardware assembly completed and alignment is in progress –A parallel-plate chopper installed –A solenoid lens installed and axial magnetic field measured –A four-quadrant beam dump fabricated and installed –Emittance scanner and Faraday cup relocated to the second chamber Simulations are still ongoing Page 17 Q. Ji, 06/29/2012 Emittance scanner

LEBT solenoids (I) Restricted space available makes it a challenge –End plates removable –Each solenoid includes a pair (X&Y) of dipole correctors Designed by TD (Kashikhin, Makarov) –Preliminary drawings have been completed –Out for bids soon (this week?) –Hope delivered ~8 months after contract awarded Page 18 ParameterValueUnits Minimum inner diameter80mm Maximum outer diameter400mm Maximum physical length140mm Solenoid strength,0.03T 2 ·m Peak solenoid current≤ 300A Power dissipation≤ 6.5kW Peak dipole coil current≤ 15A Dipole coil field integral0.5mT·m Nominal input water temperature32ºC Water pressure drop< 70psid Max water temperature rise< 30ºC

LEBT solenoids (II) Page 19 Solenoid model geometry and magnetic flux density (OPERA 3d (TOSCA) code) V. KashikhinA. Makarov

Other/Next Page 20 Discussions about ‘detailed’ layout at CMTF have started –Ready to buy shielding blocks? Bending dipole magnet –Critical path Next long lead-time item –In-house (TD) or outside design? Same as for solenoid (i.e. preliminary drawing from TD, final design and construction by outside vendor)? Built by TD? HV rack (for the source) –Similar to HINS and Linac but needs to be built Did not discuss with EE support yet LEBT Chopper (kicker and absorber) Started discussions with Controls Dpt.

Timeline? Page 21 July ’12: Shielding block ordered August ’12: Solenoids ordered November ’12: Bending dipole magnet ordered March ’13: Ion source installed at CMTF –Cave at CMTF not complete but enough for source installation in its final location Summer ’13 (early): LEBT assembly starts Fall ’13 (late): LEBT assembled & first beam through LEBT Spring ’14 (early): LEBT ready

Ion source/LEBT key personnel Likely not complete Likely not complete Page 22 PhysicistLionel Prost PXIE Lead engineerRich Stanek Civil Construction/Facility layoutJerry Leibfritz LEBT Installation/PlanningBruce Hanna Floor manager ElectricalKermit Carlson Electrical engineering supportBob Brooker Water cooling (e.g.: design, implementation)Jerzy Czajkowski Vacuum (e.g.: design, implementation)Alex Chen Controls (e.g.: power supplies)Mike Kucera InstrumentationVic Scarpine MagnetsRich Stanek, TD? Outside? Mechanical design/engineering (multiple & various needs  Multiple leaders?) Rich Andrews, Rich Stanek, Alex Chen and others as available Machine protection systemJim Steimel