Booster Losses Keith Gollwitzer PIP and MI 700 kW review January 2015

Outline Throughput, losses and beam loss power Strategy –Reduce Losses –Control Losses Tasks –Aperture and Alignment –Cogging –Notching –RF Discussion Summary 01/21/2015Keith Gollwitzer | Booster Losses2

After PIP, maximum flux could be 2.5e17/hr Beam Throughput of Proton Source 01/21/2015Keith Gollwitzer | Booster Losses3

Beam and Losses through Cycle Beam Intensity Beam Power Loss RF Capture Transition Extraction 700 MeV Notch 01/21/2015Keith Gollwitzer | Booster Losses4

Beam Loss Power -- Historical Look 2003: 525 W Administrative Limit Allows work on components Beam Loss Power is calculated from the number of protons lost per turn and the beam energy at each turn 01/21/2015Keith Gollwitzer | Booster Losses5 Beam Loss Power is almost evenly split between RF Capture, Notching & Transition

Beam Loss Power & Activation Strategy Reduce Losses/Beam Loss Power –Move Notching from 700 MeV to 400 MeV to Linac Require ability to do Magnetic Cogging to reduce Booster Notching energy –Open aperture Need stable orbit –Better RF capture Additional RF Harmonic RF cavity Control Losses –Booster Notching System now has an absorber –Use collimation system to control losses Need to change Cogging from Radial to Magnetic 01/21/2015Keith Gollwitzer | Booster Losses6 Cogging is moving the Booster notched gap to align with the desired MI/RR RF bucket Discussed later

Aperture – Orbit Control First 30+ years of Booster only had DC correctors Within the last decade, new 48 correction packages –12 poles with wiring circuits to do orbit and optics control –Power supply package capable of ramping throughout cycle –Correctors strength greater than before At beginning of PIP, software developed to take advantage of ramping –Consistent throughout ramp Orbit position Tunes Working on higher order corrections 01/21/2015Keith Gollwitzer | Booster Losses7

Aperture – Orbit Control Software development –Localized orbit bumps Verified bump is local and BPMs measure expected orbit difference Done at several points along ramp –Automated raster scan of orbit Aperture measurement Determine aperture center Determine BPM offset 01/21/2015Keith Gollwitzer | Booster Losses8

Aperture Injection Extraction 01/21/2015Keith Gollwitzer | Booster Losses9

Girder (Magnet) Realignment On each Girder are –F combined function magnet –D combined function magnet –Corrector package which also includes a BPM Non-ideal alignment known for a long time Years of orbit tuning to compensate As-found survey verified mis-alignment Fragile connections To date four moves have been done –Future moves -- if convinced limiting aperture 01/21/2015Keith Gollwitzer | Booster Losses10

#1 D F F D #2 #3 D F F D #4 #5 D F F D #6 #7 D F F D #8 #9 D F F D #10 #11 D F F D #12 #13 D F F D #14 #15 D F F D #16 #17 D F F D #18 #19 D F F D #20 #21 D F F D #22 #23 D F F D #24 +5mm -5mm 0 +5mm -5mm 0 Adjust Two Girders Four magnets were realigned on Aug. 6, upstream: 0mm 15-3 downstream: +0.6mm 15-4 upstream: +0.7mm 15-4 downstream: +1.3mm 16-1 upstream: -1.3mm 16-1 downstream: -1.3mm 16-2 upstream: -1.3mm 16-2 downstream: -1.3mm 1.3 mm 01/21/2015Keith Gollwitzer | Booster Losses11

Adjustment of Two Girders Before Move4 After Move4 +/-0.8mm Vertical Difference Orbit 01/21/2015Keith Gollwitzer | Booster Losses12

Cogging Allows notched gap to be synchronous with the transfer from the booster to the desired MI/RR RF buckets Booster 15 Hz ramping is synchronized to the 60 Hz power line which leads to field errors Number of MI/RR revolution Simulation Measurement 01/21/2015Keith Gollwitzer | Booster Losses13

Radial Cogging in use Path length (radial position) of the beam is 700 MeV Radial position Intensity Creates notch at 700MeV. Moves orbit before/after transition. 01/21/2015Keith Gollwitzer | Booster Losses14

Magnetic Cogging uses 48 Dipole Correctors Changed by dipole corrector Dipole corrector: 24.4[A] B field error ~1% can be compensated. Keeps beam on central orbit and save aperture. Creates notch anytime  reduces beam power loss Magnetic Cogging system can also be used with Linac notch system 01/21/2015Keith Gollwitzer | Booster Losses15

Magnetic Cogging Status Development of new hardware board –Input signals from MI/RR RF, Booster RF, Dipole field –Digital output signals for notching, transfer kickers, rev count –Analog output of drive signal for dipole correctors Software developed –Determine bucket error –Apply cogging feedback Gain is ramped –Control synchronization –Generate diagnostic signals Beam testing is on-going –Operational soon +/- 1 buckets Number of MI/RR revolution 01/21/2015Keith Gollwitzer | Booster Losses16

Notching System Booster is h=84 Booster extraction & MI injection kickers’ rise times are ~50ns Transfer kickers’ rise time corresponds to 3 RF buckets No notching done for many years –Booster extraction kicker sprayed beam… Three 1 meter notcher-kickers introduced a dozen years ago dumped beam onto collimator –Most activated region in Booster –Notching occurs early in cycle 400 MeV for non-cogged cycles 700 MeV when Radial Cogged Notching Goal –15ns rise and fall times with 3 bucket flat top 01/21/2015Keith Gollwitzer | Booster Losses17

Notching System – PIP Work Moved notcher-kickers & installed engineered absorber –Ran next slide for reduced activation Replace notcher-kicker system –Six half-meter notcher-kickers –New power supply system –Entire system operational Oct ‘14 Short Kickers – drop in replacements Absorber NoVA Style 01/21/2015Keith Gollwitzer | Booster Losses18

The plot above shows the difference between two radiation activation surveys after running similar flux for a week. The new system has greatly reduced residual activation in several areas of Booster. The new notcher system directs the beam to an absorber – old system was not designed for high flux and the kicked ‘notched’ beam into collimators -- uncontrolled Rad Survey Data Dec 2013 Notcher Absorber Collimators Activation decrease of ~1200mrem/hr Notcher Absorber Controlling Beam Losses 01/21/2015Keith Gollwitzer | Booster Losses19

Linac Notch System 01/21/2015Keith Gollwitzer | Booster Losses20 Neutralize portion of the 750 keV beam using a pulsed laser –Create laser pulse pattern for 200 MHz and 450 kHz –Amplify pulse using a three-stage fiber amplifier –Create spatial uniform photon beam –Insert laser into a zig-zag interaction cavity 200 MHz pulses 450 kHz “notch” spacing RFQ Quad H-H- Laser beam into page (not shown) Flange-cavity located between RFQ and MEBT Quad

Linac Notch System – Preliminary Results 01/21/2015Keith Gollwitzer | Booster Losses21 Wall current monitor Neutralization of a single bunch by a laser done earlier this month. Continuing effort towards an operational laser notch system.

Additional Cavities and Harmonic Cavity (CY Tan talk) Harmonic cavity will help with beam capture. Increasing the number of cavities from 19 to 22 will allow for a larger bucket. 55 KV,15Hz Thermal Profile Magnetic loss density (100 kV) 01/21/2015Keith Gollwitzer | Booster Losses22

Uncontrolled Beam Loss Power Discussion Administrative Limit was set when the Notching system did not have a dedicated absorber; all losses were uncontrolled The dedicated Booster Notching system absorber has reduced the activation of components –Administrative Limit can be re-evaluated Notching in the Linac (some clean-up in Booster) reduces the total Uncontrolled Beam Loss Power by ~27% Activation is limited by individual loss monitors –Controls activation of local components 01/21/2015Keith Gollwitzer | Booster Losses23 15 Hz scaling of Beam Loss Power 960 W Notching 700 MeV to Linac 700 W Collimation Additional RF Harmonic RF Tuning

PIP Future Work to Reduce Losses Near Term –Magnetic Cogging: make operational –Update damper systems –Upgrade Booster BPM system –Linac Notch system: complete, test & commission Booster system will be used to clean gap after beam capture Longer Term –Booster RF Additional RF cavities Harmonic cavities –Booster Collimator After Magnetic Cogging system is operational, do thorough testing of current set of collimators –Use or possibly design an appropriate collimation system 01/21/2015Keith Gollwitzer | Booster Losses24

Summary As PIP realizes 15 Hz capability, –Proton flux will increase to meet the demands of the Fermilab program –With increases of the flux, we will need to keep losses/activation at the same level or less than now Will continue to work on decreasing inefficiency Notching requires beam loss –Notch at lower beam energy to reduce power loss –Notched beam is controlled/contained Magnetic Cogging allows notching to occur at lower energies Collimation to be implemented to control losses 01/21/2015Keith Gollwitzer | Booster Losses25