# Presentation: 352902

## Proton Plan

- Eric Prebys
- FNAL Accelerator Division

## “Proton Plan”

- The details of proton demand and issues can be found in an official report to the director at:
-   www.fnal.gov/directorate/program_planning/studies/ProtonReport.pdf
- Working assumptions:
- Existing proton source must last at least another 10 years or so in more or less it’s current configuration.
- During that time, a new “proton driver” will be built, which will ultimately replace the existing proton source.
- Proton source improvements should require no significant downtimes beyond those needed for other reasons.
- The maximum total funding for proton source improvements will be of the order of $18M over the next few years.
- Near term projects most important to performance

## Scope of Improvements

- The level of funding *precludes* some things which have been discussed:
- Replacement or major upgrade of 200 MHz linac
- Official policy on 7835 PA’s: keep fingers crossed.
- Decrease of Main Injector ramp time
- Unless it is done as part of Proton Driver
- For this reason, the proton plan focuses primarily on the Booster
- Decreasing uncontrolled losses.
- Increasing reliable average repetition rate.
- Biggest decisions involve plan for RF system.

## What Limits Total Proton Intensity?

- Maximum number of Protons the Booster can stably accelerate: 5E12
- Maximum average Booster rep. Rate:  currently 7.5 Hz, may have to go to 10 Hz for NuMI+ *(full)* MiniBooNE
- (NUMI only) Maximum number of booster batches the Main Injector can hold: currently 6 *in principle*, possibly go to 11 with fancy loading schemes in the future
- (NUMI only) Minimum Main Injector ramp cycle time (NUMI only): 1.4s+loading time (at least 1/15s**nbatches*)
- Losses in the Booster:
- Above ground radiation
- Damage and/or activation of tunnel components

*Our biggest worry at the moment!!!!*

## Early Efforts

- Shielding and reclassifying Booster towers.
- More sophisticated loss monitoring methods.
- Extraction notch:
- Kick notch in beam early in cycle to reduce loss at extraction.
- Install ramped corrector system.
- Used to reduce losses at specific locations.
- Ultimately limited by corrector strength.
- Replace Long 3 extraction septum and power supply:
- Increase maximum average rep. rate.
- Increase efforts to understand the physics of the Booster.

## Booster Modeling Efforts

- At the beginning of 2001:
- The transverse lattice model for the Booster was the ideal lattice of TM-405:
- No correctors
- No injection or extraction elements
- No higher order moments
- Etc.
- There was no realistic longitudinal model.
- It was believed that space charge at injection was a significant problem.  A group formed to study...
- Now:
- Transverse model includes
- All correctors
- All injection and extraction elements
- Body multipoles
- Alignment data
- Detailed longitudinal model, verified by measurement.
- Believable space charge simulations, verified by measurements.

## Results of Modeling Efforts

- Space charge effects, while present, do not appear to be a huge effect.
- Larger Issues:
- Dogleg effect.
- Distortion at injection cause by extraction doglegs.
- Major discovery. Became focus of our efforts.
- Beam motion:
- Misalignment
- Limited correctors
- Horizontal slewing due to underpowered injection bump magnets (ORBUMP).
- RF Power limitations:
- Existing RF marginal to get beam through transition.

## Big Improvements in the Last Year

- Primary extraction “dogleg fix”
- Increase spacing between magnets in chicane system
- Reduces distortion to injection lattice by ~40%
- Vertical alignment
- Eliminate 1⁄4” misalignment at collimator region
- Improve high field orbit
- 400 MeV line work
- Better understanding
- Improved stability and repeatability
- Injection bump (ORBUMP) improvements
- Improved water flow
- New, lower resistance capacitors
- Much more reliable
- Collimator installation and commissioning

## Proton Demand

- Have now exceeded initial NuMI needs!!!!

- 7.5 Hz

## How far have we come?

- Typical:
- 5.5E12 protons/batch to stacking (Run II handbook = 5E12)
- >7E16 pph to MiniBooNE (MiniBooNE goal 9E16)
- Records:
- 6E12 protons/batch to stacking
- 8E16 pph to MiniBooNE

- Time (s)

- Oct. 2002 (MB turn-on)

- Jan. 2004

- Energy Lost

- Charge through Booster cycle

- Now

## Effect of increased intensity (recent running)

- Energy Lost per proton

- Protons per pulse

- 4E12

- 5E12

- ~5% more losses (activation) at 5E12

- Can really deliver 5E12 efficiently for the first time!!!!!

## Activation History In Booster

- MiniBooNE

- 16x proton increase

- x2~3 activation

- Collimators

## Effect of Collimators

## Effect of Collimators by Region

## Change In Activation Since Collimators

- Collimatorregion

- RF Region

- L13Extraction

- L3 Extraction

## Activation in RF Cavities – Big Success!!

- MiniBooNE

- Collimators

- Pre-MiniBooNE levels!!

## Basis of activation assessment - Dose to Workers

- Administrative limit at 300 mRem/qtr
- This is “ok”, but we don’t want to get any worse

- MiniBooNE

## Status before shutdown

- Exceeding Run II intensity goals
- Can deliver 5E12 protons per batch with good efficiency
- Regularly delivering ~80% of MiniBooNE goal
- Demonstrated NuMI intensities.
- Headroom left for at least some 8 GeV line operation.

## Major Performance-related Shutdown Projects

- Modify L13 extraction region:
- Overall ~5 reduction in original “dogleg effect”
- Factor of 3 reduction over present effect
- Adding 19th RF cavity:
- Use large aperture prototype
- Increase maximum batch size (~6.5E12)
- Increase reliability (can run with one failure)
- Prep. for 20th  cavity next year
- Complete modern laser tracker 3D network and as-found in the Booster and 400 MeV line:
- Will be used to fully align the Booster next year
- Move “pinger” girder to period 5:
- Extraction pre-notch will now fire into collimators
- Phased to aid extraction at *both* extraction regions!

## Issues for the Longer Term

- Linac
- Quad supplies very old, reliability concern.
- Unstable filament current has been a recurring problem.
- In general, instrumentation is inadequate, particularly in the Low Energy Linac (LEL).
- LEL LLRF in need of an upgrade.
- Nothing planned which will dramatically increase *peak* performance.

## Issues (cont’d)

- Booster
- Injection bump system (ORBUMP) must be replaced (discussed shortly).
- Will affect both rep. rate and performance
- Alignment
- RF
- Reliabilty
- Power
- Instrumentation
- Existing system limited, inconsistent, and not compatible with 15 Hz operation

## Issues (cont’d)

- Main Injector
- Aperture
- RF
- Existing RF not powerful enough for potential protons from Booster

## ORBUMP Replacement

- The existing injection bump (ORBUMP) system has several major problems:
- Magnet and power supply heating limit the average rep. rate to ~7.5 Hz.
- The system is not powerful enough to bump the beam the required amount, resulting in close to a *centimeter* of horizontal beam slewing at injection!
- Power supply switch network based on a large number (48) of obsolete SCR’s.  Maintenance an issue.
- Working on a new magnet and power supply:
- Magnets based on ferrite. Heating not an issue.
- New power supply.
- Higher rate capacitors
- Modern SCR network
- Modern charging controller
- Entire system good for full 15 Hz
- Powerful enough to eliminate injection slewing.
- Hope to be ready to install early to mid 2005.

## Booster Alignment

- It has long been realized that there are significant alignment problems in the Booster.
- These cause losses both through aperture reduction and beam motion.
- Last year’s vertical as-found uncovered significant problems, which were addressed.
- Over the shutdown, we are in the process of a full laser-tracker 3D network and as-found of the Booster.
- We will use that information over the next year to come up with an optimum set of horizontal moves.

## Booster RF Cavity Options Considered

- Move forward with 5” prototype design?
- Design complete and tested
- Could begin procurement and construction immediately in FY05.
- Aggressive schedule could have cavities in place by 2007
- Cost: ~6M
- Completely new design?
- Could be designed with higher GE voltage and reduced HOM.
- Frequency range a challenge
- Could have design by end of 2005, cavities in place by 2008
- Control losses with alignment and collimators?
- Based on our successes to date, it appears we can
- Don’t replace

- This is my preliminary recommendation

## Solid State RF drivers

- Existing system is by far our biggest maintenance item.
- Usually the older PA’s
- Average 11⁄2 per month out of 17 cavities -> MTBF of 1 year.
- >$400K just for replacement cascode tubes.
*The technicians who service these tubes receive some of the highest average radiation doses at the lab.*
- Newer solid state tubes much more reliable
- MTBF of at least 3 years.
- More or less identical to MI
- Prototype running in Booster for three years.
- Upgrade can be combined with necessary Main Injector Upgrade.

## Corrector Packages

- The Booster contains corrector packages at each of the 48 sub-periods.
- Horizontal trim
- Vertical trim
- Quad
- Skew quad
- The trims are not powerful enough to control the orbit throughout the cycle
- The quads are not powerful enough to fully control the tune/coupling throughout the cycle

## Corrector Package Specifications – Position Control

- Observed Beam Motion and Slew Rate
- Specification:
- Motion: +- 1 cm of motion at all fields
- Slew rate: 1 mm/ms at all fields

## Corrector Specifications – Tune Control

- Observed tune variation:
- Specification:
- Tune: +- .1 unit of tune at all energies
- Slew rate: .01 unit/ms at all energies

## Corrector Specifications

- Field specifications:
- Roughly 3-4 times present system

| Type | Max. Field | Max. Slew Rate |
| --- | --- | --- |
| Horizontal Trim | .009 T-m | .5 T-m/s |
| Vertical Trim | .015 T-m | .8 T-m/s |
| Quadrupole | .08 T-m/m | 8 (T-m/m)/s |
| Skew Quadrupole | Same as now | Same as now |

## Booster Instrumentation

- The existing Booster instrumentation is a mish-mash of different technologies
- Most devices are read out through MADC channels
- Limited by C190 multiplexing
- Not capable of reliable 15 Hz operation.
- The BPM’s are read out through a dedicated digitization system;
- Capable of turn-by-turn readout of the entire system, BUT
- Very slow to read out entire system.
- Non-standard data interface complicates analysis.
- Existing digitizers no longer available.
- BLM system read out by IRM system:
- Good to full 15 Hz.
- No channel limit.
- Is there something better now?
- Plan
- Work with instrumentation this year to determine the best solution for Booster readout, capable of snapshotting the entire Booster on and event-by-event basis.

## Higher Harmonic Operation

- By adding a 30 Hz compononent to the Booster magnetic lattice, we could reduce the maximum dp/dt by ~35%, effectively increasing the RF power.
- Pursue prototype in 2005
- If successful, implement in 2006

## Main Injector RF Power Issues

## Booster/MI RF Upgrade Project

- Goals:
- Replace Booster PA’s with solid state versions, of the type used in the Main Injector.
- Add a second PA to each Main Injector cavity.
- Plan:
- Construct new PA’s and solid state drivers
- 20 for Booster
- 20 for second MI port.
- Build new modulators for MI dual PA cavities:
- Move old MI modulators to Booster.

## Money – Combined RF Upgrade

| Element | Unit Cost | Total | Max FY05 Procurement |
| --- | --- | --- | --- |
| Solid State Drivers (40) | 110 | 4400 | 3200 |
| PA's (40) | 100 | 4000 | 4000 |
| Modulator (20) | 125 | 2500 | 1740 |
| Totals: |  | 10900 | 8940 |

- Solid State RF Upgrade (Main Injector + Booster)
- These are the projected total costs, and the maximum useful procurement money in FY05.
- This spending profile could have a complete system in place in both machines at the end of FY06.

## Other Projects

- Linac
- Quad Supplies:                    	250K
- Improved Instrumentation: 	100K
- Filament Stabilization:		100K
- Laser chopping R&D:		100K
- Source R&D:			 50K
- Subtotal:				600K
- Booster
- ORBUMP Power Supply:		200K
- 30Hz Harmonic prototype:	  50K
- Corrector Upgrade:		200K
- New Pinger System:		100K
- Instrumentation R&D:		100K
- Subtotal					  650K
- Total:				         	1250K
- Proposal:  Fund these projects and as much of the RF Upgrade as we can.

## Approximate Timeline

- 2004
- Collimators commissioned and fully operational
- L13 Modification
- Vertical and RF cavity alignment
- Complete alignment network and as-found
- 19th RF cavity added to Booster
- 2005
- New ORBUMP magnets and Power supplies.
- Horizontal alignment
- Procurement for solid state PA’s
- Design and procurement for new corrector system
- Begin new quad supplies for linac
- Design and procurement for new Booster instrumentation
- 2006
- Complete installation of solid state PA’s (fast track)
- Fabricate new corrector system
- Install 30 Hz harmonic, if recommended
- 2007
- Complete new corrector system

## High Rate Booster Operation

- Once the ORBUMP is upgraded, the entire Booster will be capable of running at 15Hz, with the exception of the RF system.
- Drift tube cooling and general maintenance should allow the RF system to reach 10 Hz.
- This is enough for:
- 2 pBar batches + 5 NuMI batches every 2 seconds +
- FULL 5Hz MiniBooNE operation.
- After that, we become limited by power from the mains, so if we decide to address it, it would naturally become part of the overall feeder upgrade plan.

## Proton Projections - Booster

- Losses in the Booster continue to be the major limitation to total proton throughput.
- It is extremely difficult to make quantitative projections, so most projections are based on historical performance.
- We have now come to a point where we believe we understand the performance well enough that quantitative projections will be possible in the not-too-distant future.
- A lot of ground work has been done:
- In particular, the work to correlate activation to beam loss.

## Completion of Dogleg Work

- Caused by parasitic focusing of dogleg magnet
- Goes like square of bend angle.
- Both extraction regions ~ add.
- Original magnitude:
- Max horizontal beta goes from 33 -> 47 m
- Max horizontal dispersion goes from 3.1 -> 6m
- Solution
- Spread out dogleg magnets separation by >2.
- Effect of L3 fix
- Decrease distortion from *that* side by ~5.
- Total distortion 60% of original (50% + 50%/5)
- Effect of L13 fix
- Decrease remaining distortion by ~5
- Total effect 20% of original.
- Factor of three better than prior to shutdown.
- Conclusion: After this shutdown, the Booster will be much closer to an ideal machine.

## Understanding Booster Losses

## Understanding Booster Losses

- Misalignment
- Will align this year
- Lattice slewing
- Will improve after L13 work
- Intentional L13 scraping
- Will move to collimators after lattice is improved

- Misalignment
- Will align this year
- Injection mismatch:
- 400 MeV line work
- Lattice distortion
- Improved after L13 work
- Horizontal Slewing
- Eliminated with new ORBUMP
- Notch
- Will move to collimators after shutdown

## Quantifying Booster Loss

- Main areas to understand:
- Operation of the collimators
- Helping, but still at least a factor of five away from initial predictions.
- It’s clear that up until now,  the Long 13 aperture has complicated collimator operation.
- We are working to model this.
- Beam loss related to beam position and size.
- Because we don’t have a good model of Booster beam halo, it’s difficult to quantitatively relate beam loss to things like beam position and beam size.
- Now that the loss pattern has become simplified, we should be able to quantify this through a series of straightforward aperture studies, beginning with the end of the shutdown.
- Potential for 30Hz harmonic:
- Can study by running at a lower energy.
- Planned for shutdown.

## Summary and Conclusions

- The Proton Source has made remarkable progress thanks to the work of countless people.
- We believe we have a realistic plan to optimize the reliability and performance of the system over the next few years.
- The main part of this plan involves the RF systems of the Booster and Main Injector, and the timescale of these projects is completely determined by how fast we spend money on them.