# Presentation: 759108

## NSLS-II Injection System

- T. Shaftan
- Accelerator Physicist
- NSLS-II Accelerator Systems Advisory Committee
- July 17-18, 2008

- DOE Review of NSLS-II Project, Dec. 12-14, 2006

## Acknowledgements

- 	R. Heese, J. Rose, N. Tsoupas, I. Pinayev, S. Ozaki, F. Willeke, E. Weihreter, Y. Li, W. Guo, B. Nash,
-     M. Fallier, M. Ferreira, R. Alforque, S. Krinsky,
- E. Johnson, A. Blednykh, O. Dyling, R. Meier, S. Sharma, D. Hseuh, G. Ganetis, T. Shaftan, O. Singh, J. Skaritka, M. Rehak, J. O’Connor, C. Lavelle,
- P.K. Job, B. Casey, T. Mennona

- DOE Review of NSLS-II Project, Dec. 12-14, 2006

## Outline

- Introduction
- Injector design specifications and main parameters
- Injector layout
- Linac
- Booster
- Transport lines
- Storage Ring injection straight section
- Summary
- Future plans

- DOE Review of NSLS-II Project, Dec. 12-14, 2006

## Introduction

- NSLS-II requires reliable injector capable of filling and maintaining storage ring current
- Top-off mode of injection is required
- More detailed design has been developed on preliminary design of 200 MeV linac and 158 m 3 GeV booster presented at the ASAC in Oct. 2008
- Linac and booster are envisioned as semi-turnkey procurements
- Transport lines and ring injection straight are going to be built by BNL

- DOE Review of NSLS-II Project, Dec. 12-14, 2006

## Storage Ring Parameters Related to Injection

| Parameters | Value |
| --- | --- |
| Energy, GeV | 3 |
| Circulating current, A | 0.5 |
| Circumference, m | 792 |
| Revolution period, s | 2.6 |
| RF frequency, MHz  | 500 |
| Circulating charge, C | 1.3 |
| Total number of RF-buckets | 1320 |
| Number of filled buckets | 13204/51080 |
| Charge per bunch, nC | 1.25 |
| Beam lifetime, hours | 3 |
| Top-up cycle time, min | 1 |
| Beam current change between top-ups, % | 0.55% |
| Charge variation between top-up cycles, nC | 7.3 |

- DOE Review of NSLS-II Project, Dec. 12-14, 2006

## Requirements for NSLS-II Injection

- Discussed with users on their desired bunch patterns and top-off formats
- Two bunch patterns are in NSLS-II baseline:
- 4 or 5 bunch trains with shorter gaps totaling about 80% of the full buckets
- uniform fill with 20% ion-clearing gap
- Complex bunch patterns (camshaft bunches or 100% uniform fill) are not precluded and foreseen as future upgrades.
- Current stability and purity
- Relative current stability of 1% is the baseline number.
- Charge in empty bucket <10-4 x nominal charge
- Minimum interval between two consecutive top-off is 1 min.
- Gating signal to users is to be provided.

- NSLS-II bunch patterns

- 1 turn

- DOE Review of NSLS-II Project, Dec. 12-14, 2006

**Notes:**
Building in enough flexibility
Second gun

## Top-Off Injection Scenario

- NM bunches in the injected train
- Filling NM consecutive buckets in the ring
- Sequentially shift the injection timing
- 1 Hz injector rep rate suffices with pulse train injection
- 1 minute between injector cycles for top-off
- Interacting with users on the requirements for top-off and complex bunch patterns
- Developed simulation on SR pattern non-uniformity
- Evaluated rate of contamination of “empty” buckets by Touschek-scattered particles

**Top-Off Injection Scenario**

- 80 bunches in injected train
- 150 bunches in injected train

- DOE Review of NSLS-II Project, Dec. 12-14, 2006

## NSLS-II Injector Complex Overview

**NSLS-II Injector Complex Overview**

- 200-MeV linac

- 3-GeV booster

- LB TL

- B-SR TL

- Injection straight

- DOE Review of NSLS-II Project, Dec. 12-14, 2006

**Notes:**
Update picture

## Linac

- SR injection: 7.3 nC/min
- 	10% loss at SR injection
- 	20% loss at booster extraction
-       30% beam loss at booster injection
- 	 15 nC per pulse
- _NSLS-II: 200 MeV, 15 nC/train, ~0.5% energy spread_
- Linac can be procured turn-key
- January 2008 we visited SOLEIL and THALES
- Acquired information regarding linac hardware, utilities and performance
- Acquired information on beam measurement data
- Participated in linac studies

- SOLEIL measurement of injected bunch train

- SOLEIL linac

- J. Rose

- DOE Review of NSLS-II Project, Dec. 12-14, 2006

## Linac Configuration

**Linac Configuration**

- 3 GHz, 100 MeV linac is in operations at ASP (ACCEL)
- 3 GHz, 100 MeV linac is in operations at SOLEIL (THALES)
- Achieved parameters:
-  4/0.25 nC/pulse in LPM/SPM at ASP
-  10/0.5 nC/pulse in LPM/SPM at SOLEIL
- Close to NSLS-II requirements
- Linac Front-End funding is planned in FY09 to procure and establish gun performance

- Thales linac

- J. Rose, R. Meier

- DOE Review of NSLS-II Project, Dec. 12-14, 2006

## Booster

**Booster**

- Booster accelerates beam from            200 MeV  3 GeV
- Tracking studies have been carried out with nearly complete ring model: booster emittance of ~30 nm is adequate for low-loss injection
- Compact (158.4 m) and low-emittance (30 nm at 3 GeV) lattice
- Accelerates bunch trains
- Repetition rate of 1 Hz
- Charge per train 10 nC
- RF system (by BNL): PETRA cavity and IOT
- Optimized injection and extraction systems: DC septa
- Semi turn-key procurement that is close to existing solution

- Lattice

-      Similar to Australian Synchrotron Project booster

- Structure

- Acknowledge work of W. Guo, Y. Li, B. Nash

- DOE Review of NSLS-II Project, Dec. 12-14, 2006

## Progress on booster lattice

- CD2  New lattice version
- Similar magnet parameters as in CD2 lattice
- Straight section length increased 7.05  7.7 m
- Vertical tune (and chromaticity) is decreased
- DA (on- and off-energy) is increased to larger than vacuum chamber aperture
- Dispersion in straight decreased to 10 cm
- Emittance is 33 nm at 3 GeV – needs more work
- Orbit correction scheme is adequate
- 20 mA in the booster: study of collective effects is under way

- Y. Li

- DOE Review of NSLS-II Project, Dec. 12-14, 2006

## Optimization of booster extraction and injection systems

- CD-2
- A single pulsed septum 150 mrad
- Assume beam divergence of 80 urad (horizontal) at extraction
- RMS beam divergence = error at:
- Kicker stability (flatness) of 1.6%
- Septum stability (flatness) of 0.05%

-  Reducing sensitivity to waveform jitter and noise
- CD-3
-  Combination of weak pulsed septum (47 mrad) and DC septum (96 mrad)
-  Kicker stability (flatness) of 1.6%
-  Septum stability (flatness) of 0.2%

- QF

- QG

- QG

- QF

- B

- B

- B

- B

- DC septum

- kicker

- pulsed
- septum

- B

- B

- B

- B

- kicker

- pulsed
- septum

- QF

- QG

- QG

- QF

- DOE Review of NSLS-II Project, Dec. 12-14, 2006

## Magnet design

- DC extraction septum

- Transport line quadrupole

- M. Rehak, R. Heese

- Magnet definition is in progress for injector:
- LB TL: 4 dipoles, 14 quadrupoles
- Booster injection and extraction system
- BSR TL: 4 dipoles, 16 quadrupoles
- Injection straight: pulsed magnets
- Transport lines:
- Quadrupoles: 2 type  of yokes, 3 types of different coils
- Dipoles: 3 types of yokes, 3 types of coils
- Correctors: 2 types of yokes, 2 types of coils
- Complex magnets: DC extraction and SR injection septa
- Soon start magnetic design of pulsed magnets

- DOE Review of NSLS-II Project, Dec. 12-14, 2006

## Layout of LB TL

- DOE Review of NSLS-II Project, Dec. 12-14, 2006

**Notes:**
Completely rework

## Booster to Storage Ring Transport Line

- DOE Review of NSLS-II Project, Dec. 12-14, 2006

**Notes:**
Diagnostics line
 BSR TL design: critically important to preserve high beam quality
 BSR TL requires flexible design sufficient for booster commissioning and setting up SR injection 

## Storage ring injection straight

- Quad-to-quad distance is 9.3 m
- Combination of strong DC pre-septum with pulsed septum
- Closed bump of 15 mm
- Kickers with 5.2 μs long pulse powered separately
- Pulsed magnets (3.15 GeV max) are within vendors capabilities

-      Magnet and PS design is under way
-      Development and optimization of pulsed magnets and PS (total of 13 magnets of 7 types for NSLS-II) in-house: Pulsed Magnet Lab in FY09

- R. Heese, M. Ferreira, D. Hseuh

- DOE Review of NSLS-II Project, Dec. 12-14, 2006

## Pulsed magnet tolerance analysis

- Study of the residual field errors in closed bump (for the maximum stored beam displacement)
- Vertical error: random kicker roll of 0.5 mrad (3.75 μrad angular vertical kick)
- Horizontal error: 0.1% kicker-to-kicker random amplitude mismatch
- Consider combination of 4 kickers and scale total to the Source Points of Short and Long Straight sections
- Compare with RMS beam size and divergence at the Source Points
- Horizontal error is of order of RMS beam parameters
- Vertical error exceeds RMS parameters
- Need set-up of Pulsed Magnet Lab to develop methods of error reduction
- Tolerance analysis is ongoing

- Horizontal error scaling for kicker mismatch

- Vertical error scaling for residual kicker roll

- Orbit angle at SP (μrad)

- Orbit angle at SP (μrad)

- Orbit shift at SP (μm)

- Orbit shift at SP (μm)

- DOE Review of NSLS-II Project, Dec. 12-14, 2006

## Injector building

- DOE Review of NSLS-II Project, Dec. 12-14, 2006

## Utilities, injector components, safety

- Multiple iterations on building layout
- 80% Title II Design complete
- Injector utilities (electric power, water, compressed gas) are specified
- Injector components
- Booster Power Supplies performance specs established
- Injector element specification is in progress
- Injector magnet design and PS specs are in progress
- Cable/signal list is compiled
- Component naming convention to be discussed
- Safety review took place
- Assessed beam parameters envelope
- Assessed beam confinement system
- Design of safety devices is under way

- NSLS-II beam
- dump design

- APS safety shutter

- R. Alforque

- DOE Review of NSLS-II Project, Dec. 12-14, 2006

## Procurements

**Procurements**

- Linac: visited THALES and SOLEIL in January
- Linac Front-End to be procured in FY09
- Booster RF: visited DESY in July
- Booster: two potential vendors visited NSLS-II in January and March
- Booster Statement of Work completed in April
- Information on:
- Scope of delivery
- Timeline
- Performance specifications
- Acceptance testing
- Conventional constructions
- Mechanical and Electrical utilities
- Diagnostics and Controls
- Norms and Standards
- Booster SOW was sent to three potential vendors for budgetary quotes and schedules
- Expecting information from two vendors in August

- DOE Review of NSLS-II Project, Dec. 12-14, 2006

## Summary

- NSLS-II full energy injector will support top-off operations in presence of limited beam lifetime
- Multi-bunch injection with high charge per bunch train
- Linac and booster are envisioned as major procurements
- NSLS-II booster is based on existing design (low-emittance cost-effective solution) with modifications
- We are moving forward with design of injection straight section and transport lines
- In the design process we use experience from other state-of-art light sources
- In the past months injector development was focused on:
- Finalizing injector building specifications
- Setting specifications on utilities, safety systems, interfaces with NSLS-II subsystems
- Optimization of the booster lattice, injection/extraction systems
- Transport line design and specification of components
- Design of the storage ring injection straight
- Interaction with vendors
- Draft of CD-3 Design Report is nearly ready

- DOE Review of NSLS-II Project, Dec. 12-14, 2006

## Important dates for NSLS-II injector

- CD-2: injection system baseline design is developed
- During FY08-FY09 we are refining design and perform value engineering effort, prepare specs for procurements
- Specifications are ready for procurement:
- Linac		Oct 09
- Booster 		Aug 09
- Booster RF		Aug 11
- Utilities		Dec 10
- TL			Mar 10
- At this point the design and specs by BNL are finalized
- Procurement begins:
- Linac		Oct 10
- Booster 		Mar 10
- TL			Apr 10
- Utilities		Nov 09
- Injector Building BOD end Nov 11

- DOE Review of NSLS-II Project, Dec. 12-14, 2006

## Extra

- DOE Review of NSLS-II Project, Dec. 12-14, 2006

## Uniformity of bunch pattern

- Requirement on SR bunch pattern uniformity is 20%
- Can we preserve the uniformity while executing top-off with bunch trains?
- “Hunt&Peck” mode of injection at SLS
- Simulation with assumptions:
- Touschek-limited lifetime
- Phase transient induced by harmonic cavity
- Noisy (20%) injected bunch train
- Filling consecutive N=80...150 buckets in one top-off cycle
- Results after 2 days of continuous top-off show no deterioration of bunch pattern
- “Hunt&Peck” mode with bunch trains to be studied

- 80 bunches in injected train
- 150 bunches in injected train

- DOE Review of NSLS-II Project, Dec. 12-14, 2006

## Maintaining purity of “empty” RF buckets

- To maintain the purity of empty buckets on 1E-4 level we will need to do cleaning ~every 3 min
- Very first energy band is located at 4.3% off the nominal energy.
- This is a pessimistic estimate assuming no limits on machine energy acceptance. Real energy acceptance (limited by a scraper) will reduce migration rate.
- This analysis includes only Touschek-scattered particles migrating from full to empty buckets. In reality there will be additional particles coming from injected beam every top-off cycle.
- Needs an analysis of the bunch cleaner in the booster.

- DOE Review of NSLS-II Project, Dec. 12-14, 2006

## Booster RF System

- Signed MOU with DESY for two 5-cell PETRA cavities, to be delivered in early FY2009
- Need to work out coupler interface

- DOE Review of NSLS-II Project, Dec. 12-14, 2006