# Presentation: 540483

## NSLS-II Injection System

- T. Shaftan
- NSLS-II Accelerator Systems
- Advisory Committee
- October 11, 2006

## Contributors

- I. Pinayev,
- J. Rose,
- J. Skaritka,
- R. Heese,
- C. Stelmach,
- S. Pjerov
- S. Sharma,
- L.H. Yu
- T. Shaftan

- G. Ganetis,
- D. Hseuh,
- N. Tsoupas,
- W. Meng,
- J. Beebe-Wang,
- A. Luccio,
- D. Raparia
- D. Wang

-  J. Safranek,
-  L. Emery,
-  W. Joho

## Outline

- NSLS-II injection requirements
- Considerations for injection system
- Injection straight arrangement and simulations
- Low energy accelerator
- Booster
- Transport lines
- Concluding remarks

## Requirements for NSLS-II Injection

- High reliability
- Reasonable fill speed
- Low losses
- Low power consumption
- Lifetime 3 hours (with 3rd HC)
- Top-up
- Stability of current <1 %
- Time between top-up injections >1 min
- Bunch-to-bunch variations of charge <20%

## Ring parameters related to injection

| Parameter | Value |
| --- | --- |
| Energy, GeV | 3 |
| Circulating current, A | 0.5 |
| Circumference, m | 780 |
| Revolution period, s | 2.6 |
| RF frequency, MHz (wavelength, m) | 500(0.6)	 |
| Circulating charge, C | 1.3 |
| Total number of buckets | 1300 |
| Number of filled buckets | 13004/51040 |
| Charge per bucket, nC | 1.25 |
| Lifetime, hours | 3 |
| Interval between top-up cycles, min | 1 |
| Current variation between top-up cycles, % | 0.55% |
| Charge variation between top-up cycles, nC | 7.15 |

## Injection Scenario

- NM=20-100

- Injected bunch train

- #

- Ring bunch pattern

- t

- t

- 1st turn

- 2nd turn

- 3rd turn

- Ib

- kicker

- Many (~1000) bunches in the ring  multi-bunch injection
- NM bunches in injected train
- Filling NM consecutive buckets in the ring
- Sequentially shift injection timing
- 1 Hz repetition rate suffices with pulse train injection
- 1 minute between top-up cycles
- Kickers duration can be 2 turns long (5 sec) or even longer
- Considered in ALS top-up (10 bunches)

## Injection straight design

| Ring Injection Kickers (4) |  |   |
| --- | --- | --- |
| Field, T | 0.193 |  |
| Length, m | 0.75 |  |
| Angle, mrad | 14.4 |  |
| Current Amplitude, kA | 5.34 |  |
| Voltage, V | 4500 |  |
| Temporal shape | 5 μsec 1⁄2 sine wave |  |

| Pre-septum magnet |  |   |
| --- | --- | --- |
| Field, T | 1.1 |  |
| Length / Angle, m / mrad | 0.75 / 83 |  |
| Peak current/voltage, kA/kV | 12/0.6 |  |
| Pulse shape | 100 μsec 1⁄2 sine wave |  |
| Final Injection Septum |  |   |
| Field, T | 0.9 |  |
| Length / Angle, m / mrad | 0.5 / 45 |  |
| Peak current/voltage, kA/kV | 10/0.6 |  |
| Pulse shape | 60 μsec full sine wave |  |

- I. Pinayev and R. Heese

## Requirements on Ring Stay-Clear

- Tracking is done with TRACY-2
- Tracking a set of particles corresponding to injected beam
- Tracking for 500 turns
- Beam envelope is recorded at every ring turn on every element
- Tracking for 10, 50, 100 nm
- Black envelope: scaled septum aperture for horizontal
- Scaled undulator gap for vertical
- Conclusion: stay-clear required for injection can be easily met

- J. Rose, I. Pinayev and J. Bengtsson

## NSLS-II injector

## Low-energy accelerator

- Specifications for NSLS-II linac:
- Energy 200 MeV,
-      energy spread <0.5% RMS, emittance ~100 nm at 200 MeV
- Defined by small vacuum chamber in the booster
- Soleil linac:
- 10 nC in 300 ns at 100 MeV
- Energy spread <0.5% RMS
- Emittance ~40 mm mrad
- Beam loading compensation
- Fits NSLS-II requirements
- Turn-key system

- Soleil linac

- Measured bunch train along the linac

- from: A. Setty et al., Commissioning of the
- 100 MEV ...

## Layout of 200 MeV linac

-  5 linac sections
-  3 klystrons
-  With loss of one klystron: 177 MeV

- J. Rose

## Linac-to-booster Transport Line

- Length: 19 meters
- 2 dipoles, 8 quadrupoles,
-     4 correctors
- Energy spectrometer
- Safety shutter
- Flags, BPMs
- Loss monitors
- Diagnostics set-up sufficient for commissioning of the linac

- I. Pinayev

## Booster: design considerations

| “Compact” booster | “Same tunnel” booster |
| --- | --- |
| Building and shielding are very expensive | Higher cost for vacuum, diagnostics |
| Ability to commission booster in advance | OK, based on the SLS experience |
| Ability to service and troubleshoot without beam interruption | Lifetime is 3 hours  Average hardware failure leads to stop anyway  |
| “Conventional” design | Higher beam quality, relaxed tolerances |

## Booster location

- Mounting on the ceiling
- No expanding tunnel
- No transport lines blocking tunnel pathway
- No magnets above ring straights
- No water-cooling for magnets
- Cross-talks?

**Notes:**
Replace the picture

## Booster parameters

| Parameter | NSLS-II | SLS |
| --- | --- | --- |
| Energy range [GeV] | 0.2 – 3.0 | 0.1 – 2.4 |
| Circumference,[ m] | 780 | 270 |
| Emittance [nm] | 11.5 | 9 |
| Repetition rate [Hz] | 1 | 3 |
| Radiation loss per turn [keV] | 500 | 233 |
| RF frequency [MHz] | 500 | 500 |
| Magnet power [kW] | 75.3 | 150 |
| RF voltage [MV] | 1.0 | 0.5 |
| RF acceptance [%] | 1 | 0.43 |
| Beam current [mA] | 3 | 1 |
| Momentum compaction | 5.7·10-4 | 5·10-3 |
| Tunes [x / y] | 19.19 / 10.73 | 12.41 / 8.38 |
| Chromaticity [x/y] | –21.7 / –21.7 | –15 / –12 |
| Damping times [ms] (x / y / E)  | 22 / 31 / 19 | 11 / 19 / 14 |

## Booster lattice

- Dynamic Aperture

- Modified NSLS booster lattice
- 60 combined function dipoles
- 90+6 quadrupoles
- 15+15 sextupoles
- 60 X-Y correctors
- 75 BMPs for orbit correction, rms orbit < 1mm
- Dipole field 0.7 T at 3 GeV
- Large dynamic aperture
- Negligible eddy current effect at 1Hz

## Booster magnets

- Magnets are located above storage ring
- Use of air-cooled coils
- Small size of vacuum chamber  small magnet size and weight
- Small power consumption
- Relaxed tolerances on magnet alignment and field errors
- Simple design of support hangers
- Quadrupoles and sextupoles: standard and compact design

## Booster Magnet Power Supplies and RF

- _In series circuits:_
- B-PS – 60 dipoles
- Q1-PS – 60 quadrupoles
- Q2-PS – 30 quadrupoles
- SF-PS – 15 sextupoles
- SD-PS – 15 sextupoles

- _ __Separate circuits:_
-  60 horizontal trims
-  60 vertical trims
-  3 x 2 quadrupole trims

-  All power supplies can operate at 1 Hz
-  Programmable ramping profiles
-  Synchronization from line voltage

- G. Ganetis

- J. Rose

- RF voltage ramps to 1 MV
- Energy acceptance 1% at 3 GeV
- Total RF power 37 kW
- Single 5-cell PETRA cavity
- Capable of delivering 1.5 MV
- IOT transmitter 80 kW at 500 MHz

## Booster vacuum

- Target average value 1E-7
- Gas-scattering losses throughout energy ramp 0.5%
- Vacuum chamber provides with > 10xRMS beam sizes in both planes
- 2 sizes of vacuum chamber:
- 20x30mm2 in dipoles
- 25x40mm2 in dispersive straights
- 5 pumps per superperiod = 150 pumps total
- Pumps in RF and injection/extraction straights

- D. Hseuh

## Booster-to-Storage ring Transport Line

- Consists of 3 parts
- Horizontal achromat
- Vertical dogleg
- Horizontal achromat
- Doublets for optimizing -functions without disturbing -functions
- Maintain small beam size along the transport line
- Magnets / diagnostics:
- 4 dipoles,
- 17 quadrupoles,
- 6 trims,
- 6 BPMs, 6 flags, 2 ICTs

- C. Stelmach, S. Pjerov

**Notes:**
6 flags

## Concluding Remarks

- We designed reliable and robust NSLS-II injection system
- Conceptual design of NSLS-II injector
- Linac will be purchased, turn-key + some R&D?
- “Same tunnel” booster
- Transport lines: sufficient diagnostics for step-by step commissioning
- Storage ring:
- Sufficient dynamic aperture for injection
- Sufficient stay-clear for injection
- Injection kicker system will be purchased, turn-key
- Future work:
- Optimization of injector design/cost
- tracking in realistic scenario,
- injection tolerances
- Consider Lambertson septum