# Presentation: 801597

## BNL Diagnostics Meeting

**BNL Diagnostics Meeting**
**Feb. 5-6, 2004**
**Held at BNL **
**Mike Plum**

## The HEBT, Ring, and RTBT

**Ring Service Building**

**RTBT Service Building**

**HEBT Service Building**

**HEBT**

**Ring**

**RTBT**

**The HEBT, Ring, and RTBT**

## HEBT/Ring/RTBT Commissioning Schedule

- Jan/05

- Jan/06

- Jan/07

**Linac, to linac dump**
**11/Mar – 31/May/05**

**HEBT/Ring/RTBT, to extr. dump**
**6/Jul – 18/Nov/05**

**RTBT, to target**
**1/Feb – 28/Feb/06**

**CD-4 deadline**
**1/Jun/06**

## High level commissioning plan

- HEBT beam line up to arc, then on to linac dump, commissioned as part of linac commissioning (start 11/Mar/05 – 31/May/05).
- Beam current limited (by linac dump) to 7.5 kW avg. One full pulse (24 kJ) at very low rep rates is also OK.
- Start with low current beam (1 − 4 Hz, 1 − 100 us) (note: 1 ea. 38 mA, 690 ns minipulse = 26 J, and1Hz, 100 us, 26 mA avg (38 mA chopped) = 2.4 kW)
- Should be able to use single mini pulse beam to steer beam to dump.
- Steer beam through collimators using BPMs and loss monitors.
- Check that BPM’s, BLM’s, BCM’s, WS’s all functioning.
- Check beam emittance and match to HEBT using the four wire scanners at the beginning of the HEBT (WS01-04).

## High level commissioning plan (cont.)

- Commission up to ring extraction dump (6/Jul/05 – 18/Nov/05).
- First commission HEBT up to injection dump.
- Current limit to injection dump is about 150 uA.
- Start with low current beam (1 − 4 Hz, 1 − 100 us).
- Should be able to use single mini pulse beam to steer beam to dump.
- Check that BPM’s, BLM’s, BCM’s, WS’s all functioning.
- Check HEBT optics: Beam parameters at foil (position, emittance, Twiss parameters, achromat); beam stability at foil.
- Measure beam emittance and Twiss parameters using WS20-23, WS32). Extrapolate to ring and verify correct. Adjust if not.
- Check beam position and position stability at foil, using HEBT/IDump BPMs upstream and downstream of foil, and phosphor screen / video.
- Measure dispersion in HEBT arc, using BPMs and varying beam energy. At same time check for achromat at end of arc and at stripper foil, using BPMs and foil video.
- May want to check halo scrapers. Insert until see beam loss increase.

## High level commissioning plan (cont.)

- Next commission ring.
- Current limit to extraction dump is 7.5 uA avg. Not necessary to extract beam if power is less than a few kW (2 kW/collimator).
- Verify correct beam parameters at stripper foil using WS20-23, WS32, foil video, and BPMs.
- Verify stripper foils are in place and in good shape using foil video cameras.
- Single shot injection into ring, 1 – 4 Hz. Bump magnets off; rf off; trim, sextupole, octupole magnets off, scrapers at out limits.
- Correct closed orbit using BPM system.
- Measure betatron tune and position/angle of injected beam at foil using BPM system in ring.
*Very important: Need BPM system that works well with single shot injection (~20 mA pk, ~500 ns, ~1 mm resolution). Note: Model calculations predict that 402.5 MHz structure will dissolve after about 10 turns. Need good baseband system. *

## High level commissioning plan (cont.)

- Ring commissioning (cont.)
- Measure ring revolution frequency and check MEBT chopper period. Necessary for multi-turn injection. Use BPM and/or WCM.
- Next commission up to extraction dump.
- Keep beam current low – 1 to 10 turn accumulation, 1 – 4 Hz.
- Extract beam at about 50 us from start of injection, before beam has time to debunch.
- May need to flat-top injection bump magnets to get small beam size.
- Steer beam using BLM’s and BPM’s.
- Check for good beam transport to extraction dump.
- Check RTBT BLM’s, BCM’s, BPM’s, WS’s.

## High level commissioning plan (cont.)

- Commission up to ring extraction dump (cont.)
- Ramp beam current to 1013 ppp (CD-4 requirement).
- To get 1013 ppp, need 75 turns at 38 mA peak, but OK to inject for longer at lower peak currents (~15 - 20 mA)
- 1013 ppp at 1 Hz = 1.6 kW. Limit is 7.5 kW avg to ext. dump.
- Check injection bump magnet system using BPM’s and IPM.
- Check ring rf system using BCM and wall current monitor.
- Check that beam losses remain below operational limits.
*This is the minimum needed for CD-4.*

## High level commissioning plan (cont.)

- Commission RTBT to target (1/Feb – 28/Feb/06).
- Verify 1013 ppp to extraction dump.
- Reduce beam current to 1 – 10 turns accumulation, 1 Hz.
- Steer beam to target.
- Verify beam size and position on target, using harp and halo monitor (thermocouples downstream of proton beam window).
- We are working on a temporary phosphor screen that can be used to qualify and tune up the beam at the target.
- Check RTBT BLM’s, BCM’s, BPM’s, WS’s.
- Ramp beam current up to 1 Hz, 1013 ppp, and declare success in meeting CD-4!

## Ramp up to high power operations 

- After CD-4 need to ramp up to high power operations.
- 3 kW in ’06, 50 & 150 kW in ’07, 300 & 800 kW in ’08, 1200 & 1400 kW in ’09.
- Primary goals: run ring with acceptable beam loss* *(1 W/m of uncontrolled loss)* *and deliver beam to target with correct size and position.
- Tools needed to achieve these goals:
- Diagnostics to measure beam loss, beam lifetime.
- Fast and slow BLM system.

## Ramp up to high power operations (cont.)

- Diagnostics to measure lattice functions (betatron functions, dispersion functions, chromaticity). Needed to fine-tune ring lattice.
- BPM system, single shot and multi-turn accumulation.
- Kicker system would allow more accurate measurements and lattice function measurements at higher beam powers.
- Measure orbit response matrix (closed orbit, phase, tune, betatron amplitude vs. steering magnet and quad magnet variation).
- With ~200 turns can get good measurement of phase advance, used to verify/optimize quad settings.

## Ramp up to high power operations (cont.)

- Diagnostics to measure chromaticity (& magnets to control it). Needed to adjust chromaticity toward zero.
- BPM system.
- Kicker system would allow more accurate measurements at higher beam powers.
- Measure tune vs. injection energy.
- Diagnostics to measure beam energy.
- Fast BCM and/or wall current monitor.
- Measure revolution period for a few hundred turns after end of injection, with rf off.
- Diagnostics to measure beam halo.
- Halo scrapers.
- Beam losses caused by halo will likely be the ground on which we spend most of our time fighting.

## Ramp up to high power operations (cont.)

- Diagnostics to measure structure resonances (& magnets to control them).
- Loss monitor system.
- BPM system (and kicker system preferred).
- Measure beam loss (and tune) as move low-intensity tune across resonance line.
- Diagnostics to measure longitudinal profile.
- Needed to verify MEBT chopper frequency.
- Needed to set up 1st harmonic rf system and 2nd harmonic rf.
- Fast BCM and/or wall current monitor.
- Tune phase to get symmetric bunch shape.
- Tune amplitude to keep gap clear of beam.

## Ramp up to high power operations (cont.)

- Diagnostics to measure evolution of beam profile.
- WS in extraction line, or non-intercepting beam profile monitor, e.g. IPM (preferred).
- Verify that injection painting is working as planned.
- Diagnostics to measure coherent space charge tune shift.
- Coherent tune kicker.
- Measure tune as a function of beam intensity.
- Diagnostics to measure beam in gap.
- Halo scrapers & BIG kicker.
- Diagnostics needed to address electron cloud issues.
- Electron probes.
- Wide bandwidth BPM.

## Ramp up to high power operations (cont.)

- Diagnostics to estimate incoherent tune, tune spread.
- 50 MHz dipole kicker/pickup.
- Quadrupole kicker/pickup.
- Diagnostics to measure beam transfer function
- 50 MHz dipole kicer/pickup.

## HEBT/Ring/RTBT diagnostics risk table

| Diagnostic | Risk if don’t have |
| --- | --- |
| BPM | Can’t steer beam. Can’t deliver beam. Can’t set ring injection and tune. Can’t meet CD-4. |
| Loss Monitor | Damage to equipment. |
| Current monitor | Unable to verify beam delivery.
Cannot prove that meet CD-4.  |
| Wire scanners | Unable to verify beam optics. 
Longer (and maybe impossible) commissioning.  |
| Foil video | Unable to determine condition of foils. Long downtimes when foil deteriorates. Longer ring tune-up time. Use more foils faster. Personnel radiation exposure when replace/troubleshoot foil problems. |

## HEBT/Ring/RTBT diagnostics risk table (cont.)

| Diagnostic | Risk if don’t have |
| --- | --- |
| Coherent tune kicker | Unable to measure tunes above single-shot intensities. Unable to measure tune shift. More difficult to quantify space charge effects. More difficult to reach high beam power.  |
| Ring halo scraper | Unable to measure beam halo. Difficult to set up and use beam-in-gap clearing system. Beam halo will likely create the performance-limiting beam losses. Longer time to reach high beam power. |
| IPM | Unable to easily measure evolution of beam profile in ring. More difficult to reach high beam power. More difficult to verify injection painting. Longer down time when troubleshoot problems. |

## HEBT/Ring/RTBT diagnostics risk table (cont.)

| Diagnostic | Risk if don’t have |
| --- | --- |
| Electron detectors | Makes troubleshooting electron cloud effects difficult. Longer time to reach high beam power. |
| 50 MHz dipole kicker / pickup. | Eliminates one method to measure beam transfer function & tune spread. Longer time to reach high beam power.  |
| Beam-in-gap kicker | Unable to clear beam in gap. May have high losses at extraction septum. May have lower threshold for electron-cloud instability. Longer time to reach high beam power. |
| Quadrupole kicker / pickup  | Eliminates one method to estimate incoherent tune. Longer time to reach high beam power. |
| Wideband BPM | More difficult to identify and characterize beam instabilities, e.g. e-p instability. Longer time to reach high beam power. |

## Conclusion

- Minimal set of diagnostics needed to reach CD-4:
- BPM, BCM, BLM, WS, foil video.
- Diagnostics that would reduce the risk associated with meeting CD-4:
- Coherent tune, IPM, WCM.
- Diagnostics that would reduce the risk associated with achieving high power operations:
- 50 MHz dipole kicker & pickup, quadrupole kicker & pickup, electron probe, halo scraper/detector, beam-in-gap kicker, wideband BPM.

## Slide 20

## HEBT

## Ring

## RTBT

## Slide 24