# Presentation: 210384

## AP2 & Debuncher Acceptance

- Keith Gollwitzer
- Dept. of Energy Review
- February 25, 2004

## Outline

- Overview of Goal
- Plan and Status
- What is new
- Near completion of aperture documentation
- Survey as found been performed
- LBNL study of AP2 and chromatic effects
- AP2 BPM characterization and studies
- New Debuncher BPM Data Acquisition
- Moved DRF3 cavity from dispersion region
- Change of D4Q4 from build to use existing spares
- Debuncher extraction kicker as limitation
- Additional motorized Debuncher quad stands installed
- Developing “Paint the Aperture” procedure
- Developed new combined AP2+Deb admittance measurements performed during stacking.
- Overview of Beam Studies & Schedule

## Goal: Lots of Pbars to Circulate in Deb.

- < 20 mm-mrad
- 20-40 mm-mrad
- > 40 mm-mrad

- Simulation of pbar transverse phase space (both planes) out of a 750 T/m lens.
- {2 entries for each pbar that traverses only Lithium part of lens}
* *
- Collect as much as possible for Debuncher Cooling Systems

-  *35**** mm-mrad aperture allows 320**** mm-mrad beam emittance*

## Realization of 35 mm-mrad

- 	Identify & Understand Restrictions
- 		Documentation Research
- 		Optical Survey
- 		Lattice Modeling
- 			LBNL study of AP2 chromaticity
- 		Instrumentation
- 		Beam Studies
- 	Mitigate
- 		Redesign/modify/rebuild specific elements
- 		Align/relocate specific elements
- 	Beam Based Alignment
- 		Lattice Model
- 		Instrumentation
- 		Orbit control
- 		Beam Studies

## Identifying Limitations
and Lattice Models

- and Lattice Models

## Identify Restrictions

**Building detailed lattice models**
**	**Tech Div has performed documentation research
- 		Verifying drawings with components
- 		Produced tables of all apertures
- 	Optical Survey
- 		Determine alignment of AP2 & Debuncher components
- 		Determine alignment of AP1, target hall & AP2
- 	Verify lattice parameters
- 		Beam studies using upgraded instrumentation** **
**Models (OptiM & MAD)**
**	**Local & LBNL investigations
- 		Identify restrictions and orbit control tolerances
- 		Propose resolutions

- Final Checkout

- Data 90% taken

- Crunch numbers

- Continue to feed into models

- Preparing to perform

## MAD Model and Studies by LBNL

- LBNL: I. Reichel, M. Placidi & M. Zisman

## MAD Simulations and Studies by LBNL

## Instrumentation

## Instrumentation Upgrades

**Debuncher BPM system**
- Old original electronics and Data Acquisition.
- Reliability, maintenance and ease of use were issues
- New Electronics and Data Acquisition installed
- 2.5MHz Closed Orbit system
- (~50m resolution)

- Commissioned
- Making application user friendly
- Example of difference orbit from local bump

## Instrumentation Upgrades

**AP2 BPM system**
- Want to make measurements using reverse protons
- Old original electronics and Data Acquisition.
- Reliability, maintenance and ease of use are issues
- Desire <100m resolution (53MHz)
- Minimum is DAQ and software replacement
*Still*  need to see if RF electronics are sufficient
**Other**
- Re-install AP2 709 horizontal collimator
- Was re-installed; no beam studies yet
- AP2 large aperture Toroid(s)
- Beam intensity measurement along beam line
- Started discussions with vendor
- Study of whether to move SEMs

## AP2 BPM Beam Studies

- Observation of 53 MHz modulated reverse proton beam on AP2 BPMs
- Good signal (~5 mV) on upstream (F27) BPMs
- Injection kicker noise on downstream (AP50) BPMs

## Existing AP2 Instrumentation

| System | Stacking | Rev. prot | Fwd. prot | Comment |
| --- | --- | --- | --- | --- |
| BPMs
(34) |  | Trying | Yes | Orig AM/PM Mod & DAQ
1/2 of system see kicker  |
| BLMs
(0) |  |  |  | System removed several years ago |
| SEMs
(9) | Yes | Yes | Yes | Non-optimal phase advance between SEMs |
| Intensity
(1) | Ion Chamber | Ion Chamber | Ion Chamber | Removed 3inch toroids from 6inch beam pipe |
| Collim.
(5x2) | Yes | Yes | Yes | 2 per transverse plane & 1 longitudinal sets |
| RF for BPMs | From MI | Commis.
DRF1 53MHz | From MI | DRF1: Reverse adiabatic cavities curves to “bunch” beam  |

## Existing Debuncher Instrumentation

| System | Stacking | Rev. prot | Fwd. prot | Comment |
| --- | --- | --- | --- | --- |
| BPMs
(120) |  | Yes
Yes | Yes | Orig AM/PM Mod & DAQ
Hard to maintain & use |
| BLMs
(62) | Not really | Yes | Yes |  |
| Intensity
(1) |  | DCCT | DCCT | Measures circulating current |
| Pickups
(5) | Yes | Yes | Yes | 2 are used for  stacking TBT or studies “heater” |
| Collim. | Yes | Yes | Yes | 1 scraper per plane |
| RF for BPMs |  | Re-comm. DRF3 2.5MHz | To be used | Studies RF system; new controls |

***New System commissioned***

## Known Restrictions &
Steering Hazards

- Steering Hazards

## Known Restrictions

**Band 4 cooling tanks arrays**
**	**Vertical array gaps were designed for ~30 mm-mrad
- 		Determined that increasing the gap by 3.1mm can be done.
- 			Will decrease frequencies of upper band of system to
- 			overlap with lower band; _not_ affect overall cooling.**  **
**Move DRF2 & DRF3 to low/zero dispersion region(s)**** **
**	**** **Radiation surveys show activation
- 		-DRF3 has been re-located to low dispersion.
- 		-Looking into different schemes of where to
- 		  re-locate DRF2 and essential electronics.
**Other restrictions**
**	***Identification and solutions may have to wait for modeling, beam studies and/or mitigation of other restrictions.*
**	**Identified that the extraction kicker’s elliptical pipe is 22 mm-mrad aperture for off momentum particles.
**	****	**Appears that inserting a rectangular beam pipe will
- 		be sufficient.

**Recently Identified**

## Debuncher Extraction Kicker

**Upstream End** – Beam Profile First Turn in Debuncher– **Downstream End**
- 82% of tracked beam particles inside of current beam pipe (ellipse).
- Rectangle of same inner dimensions accepts 91%.
- Increase horizontal dimension will accept 95%: Looking into offsetting pipe in kicker, but beam fairly small when extracting (good field region?)
- Will also motorize kicker stand to center beam pipe about beam.

## Limiting Apertures

| Device | Horizontal |  | Vertical |
| --- | --- | --- | --- |
|  |  |  |  |
| Band 4 Hor. pickup | 36.8  | 36.3  | 48.7  |
| Band 4 Ver. pickup | 40.5  | 39.0  | 29.9  |
| Band 4 Hor. kicker | 36.0  | 35.5  | 48.7  |
| Band 4 Ver. kicker | 41.2  | 41.1  | 30.1  |
| Deb Extr. kicker | 109.1  | 21.9  | 35.8  |

## Steering Restrictions

**Motorize stands for septum & kickers**
- 	 Tolerances are small; desire to center devices
- 		Engineering will start by looking at existing
- 		tank motorized stands.
**Injection septum (common vacuum chamber)**
- 	 Desire injected beam to be close to closed orbit
- 		Investigating whether spare can be reworked
- 		to minimize material at down stream end.
**	**
**D4Q4 replacement & BPM removal/relocation**
- 	~No vertical tolerance for injected beam
- 		2 large spare quad LQBs will replace quad;
- 		same integrated field and fits into space.
- 		Need stand work;  have existing power supply.

- Change from build to using existing spares

##               D4Q4 Aperture         

-               D4Q4 Aperture

- No tolerance for injected beam.
- Will replace with two **large quad LQBs (pole tips drawn)**;
- increase vacuum chamber.
- Move BPM from upstream area.

## Orbit Control

## Orbit Control

_**AP2 Beam Line**_
***Started*** with 4H+4V trims
- Have ***added*** 1H+3V trims. ***Installed*** shunts on all dipoles of left bend
- Can add more trims as needed

- Vertical orbit control

- Horizontal orbit control

- Shunts

- Septum & Kicker

## Orbit Control

** ****Debuncher**
- 	Started with 13H+7V trims & a vert. plane motorized quad
- 	Have added 5 two plane motorized quads (99)
- 	Added 10 two plane motorized quad stands (03)
- 	Adding 20 two plane motorized quad stands (04)

**Where the orbit control exists**
**No available space for trims; the ring is packed**
*Yellow: Dipole Trims*
*Blue: Motorized Quads*

## Shutdown Work – Quad Stands

## Beam Based Alignment &
Beam Based Determination of Apertures

- Beam Based Determination of Apertures

## Beam Based Alignment

**Basic BBA Procedure **
- 	Excite a quad
- 		Most quads have shunts
- 	Measure response
- 		BPM systems for proton studies
- 		A Debuncher pickup for AP2 during stacking
- 	Correct Orbit
- 		Trims, shunts, motorized quad stands

## Debuncher Turn-By-Turn Instrumentation

- _Change Q731 from 350A to 375A_
- Position and Intensity Signals
- Adjusted position for injection
- Phase and Amplitude of fit of many injections

- Normally use Debuncher TBT with AP2 dipole trims and Injection elements to minimize injection oscillations

## Other Study Programs

- Heat protons in Deb and watch BLMs
-  Paint the Debuncher aperture
- Prepare known emittance/momentum
- 	reverse proton beam & kick beam up

## Paint the Aperture

- Not Fully debugged- commissioned in 1999-2000 for Debuncher.
- For each corrector, kick until beam is extinguished: then have “painted” the aperture.

- Program has no assumptions about beam emittance and distribution, so need to extinguish beam  each corrector reach is then only about ~4
- Possible Solutions:
- 	1) Be able to prepare beam to known emittance & distribution 	    consistently before exciting any trim.
- 	2) Use combinations of trims to map out more of the aperture.
- The former needs much study time to see if possible;
- 	the latter we have been pursuing....

## Admittance Measurement Methods

## Admittance Measurements

- Schottky power (log scale)

- Schottky power (linear scale)

- Loss monitors

- Extinction

- Extinction

- Beam Edge

- Beam Edge

- Debuncher horizontal scraper position (mm)

- _Circulating_ Admittance
- done by scraping heated
- reverse proton beam:
- Well defined edge and extinction (p/p ~ 0)

- _Operational_ Admittance
- done by scraping while
- stacking: Hard to define Beam edge & extinction
- (p/p is full mom. spread)

*Takes many stacking cycles; >0.5hr*

- Debuncher horizontal scraper position (mm)

## Admittance Measurements

- Schottky power (log scale)

- Schottky power (linear scale)

- Loss monitors

- Extinction

- Extinction

- Beam Edge

- Beam Edge

- Debuncher horizontal scraper position (mm)

- _Circulating_ Admittance
- done by scraping heated
- reverse proton beam:
- Well defined edge and extinction (p/p ~ 0)

- _Operational_ Admittance
- done by scraping while
- stacking: Hard to define Beam edge & extinction
- (p/p is full mom. spread)

*Takes many stacking cycles; >0.5hr*

- Debuncher horizontal scraper position (mm)

**Old Method**

## Operational Admittance Measurements

- Make separate (few minute setup) measurements of the beam edge and extinction point
- lengthen the production cycle time to 10’s seconds
- Cooling turned OFF

- Beam Edge

- Extinction Point: Schottkey power sampled seconds after injection versus Debuncher scraper; Spectrum Analyzer goes from flat line to small step in the 0.1box of left plot above

- Extinction

- Schottky power

- Spectrum Analyzer for
- several scraper positions

- Beam edge: Run scraper into beam between cycles starting a few seconds after injection; record loss monitors as function of scraper position

- Deb Hor scraper position (mm)

- scraper (mm)

- Loss Monitors (counts)

## Momentum Acceptance

- Longitudinal Schottky profile of*******p’*s filling the momentum aperture of the Debuncher.
- Bunch rotation and stochastic cooling are off.

- _NOTE_: An earlier (11/2002) measurement gives
- *p*/*p* = 4.6%

## Acceptance

|  | Measured AP2 + Debuncher (stacking) | Measured Debuncher (rev. prot.) | Smallest Aperture (lit. search) | Goal |
| --- | --- | --- | --- | --- |
| Horizontal 
(mm-mrad) | 24 ± 3  | 28 ± 3  | 35.5 
22 for off mom. | 35  |
| Vertical 
(mm-mrad) | 18 ± 2  | 20 ± 2  | 30  | 35  |
| Momentum | ±2.15% | ±2.30% | -- | ±2.25% |

## Beam Studies & Schedule

## Near Term Studies List

- _Not_ _comprehensive_. Written early Nov03, planned to complete within 6 months.

## Beam Studies Aug03-Feb04

| Commission Debuncher BPM System | 15hr |
| --- | --- |
| Commission Motorized Quad Stands | 9hr |
| Commission Debuncher Local Bumps | 36hr |
| Debuncher Orbit Correction | 7hr |
| Paint the Aperture development | 5hr |
| Reverse Protons into AP2, AP2 BPMs | 6hr |

| Aug-Sep | Nov | Dec | Jan | Feb |
| --- | --- | --- | --- | --- |
| 10hr | 20hr | 48hr | 10hr | 20hr |

| AP2  bumps | 8hr |
| --- | --- |
| Debuncher Turn-By-Turn  | 4hr |
| Admittance Measurement development | 18hr |

**Reverse Proton Studies**: majority done during down periods or (recently) when have large stacks  (4-6hr block of time).
**Stacking Studies**:           depending upon study, 5% to 100% effect on stacking for short periods of time

- Total amount of time does not include end effects (reverse proton setup and recovery)

## Major Shutdown Work

**Shutdown 2004**
- Install additional 20 motorized quad stands
- Replace D4Q4
- DRF2 Move
**Shutdown 2005**
- Wider Band 4 vertical cooling arrays
- Upgraded Debuncher Injection Septum (SD2004 ? )
- Motorized stands for Debuncher injection & extraction kickers
- Possible modifications to Debuncher extraction kicker (SD2004 ? )
- Possible implementation of AP2 chromatic correction
**Shutdown 2006**
- New Debuncher extraction kicker (if not modified during SD2005)
- Implement of AP2 chromatic correction (if not implemented during SD 2005)

## Summary

**Beam Based Alignment** will do the job:
- 	Upgrade instrumentation
- 	Better orbit control
- 		AP2 beam line
- 			Had 13 knobs, have added 10, can add a few more
- 		Debuncher ring
- 			Had 21 knobs, have added 30, will add 40 more
- 	As understanding of the lattices improve
- 	     so do the physical apertures & tolerances
- 	Upgrade/new software applications
- Will mitigate limiting apertures
- 	Redesign/modify/rebuild/relocate