NSLS-II Accelerator System Advisory Committee Review Diagnostics Design and R&D

NSLS-II ASAC Review – 7/17-18/2008 1/ 26

BROOKHAVEN SCIENCE ASSOCIATES

NSLS-II Accelerator System Advisory Committee Review Diagnostics Design and R&D

Om Singh – Group Leader July 17-18, 2008



Outline

• SR Diagnostics Hardware -- Layout & Locations

• RF BPM Resolution Requirements – Various time scale

• Standard RF BPM

• Insertion Device RF BPM

• RF BPM Electronics Evaluation

• Pin-hole Camera Resolution Simulation

• Near Term Plan

• Summary



SR Cell Diagnostics Systems – BPM & Beam Loss Monitors

3PW or BM B-Line

BPMBPM

SC FC FC FC FC SC

BPMBPM

BPMBPM

BPMBPM

BPMBPM

BPMBPM

BPMBPM

BPMBPM

A) Standard Gap RF BPM 6 per cell A) Standard Gap RF BPM 6 per cell B) Small Gap RF BPMs 2 or 3 per Cell; Button Assembly on a Stand or ID Chamber

B) Small Gap RF BPMs 2 or 3 per Cell; Button Assembly on a Stand or ID Chamber

D) Slow & Fast Correctors

C) X-ray BPMs – up to 2 / FE

ID Beamline

E) Beam Loss monitor (Location TBD) p-i-n diode detector ; 2 per cell scintillation detectors; 10 total

F) RF PUEs 2 total for top-off



SR Diagnostics Hardware Locations - Preliminary

Location Hardware

Cell 22 - 3PW Diagnostics Beamline – X-Ray pinhole

Cell 24 - BM-A Diagnostics Beamline –zone plates imaging

Cell 26 - 3PW location

1 short stripline – 0.15 m

Cell 28 -3PW location

1 short stripline – 0.15 m

Cell 30 –BM-A Source

Diagnostics Beamline –Visible Synch. imaging

Cell 30 –CH2S2A location

Vertical Scraper # 2

Cell 30 –Up of P3S4A BPM

Horizontal Scraper # 2

Location Hardware

Cell 1 (or 29) –Up of P3S4B BPM

Horizontal Scraper # 1

Cell 1 (or 29) –3PW location

Vertical Scraper # 1

Cell 7 - Upstream of ID

1 Long stripline – 0.3 m

Cell 11 -Upstream of ID

1 Long stripline – 0.3 m1 DCCT – 0.3 m

Cell 27 –3PW location

1 Short stripline

Cell 29 –3PW location

1 Short stripline

Odd Cells Even Cells


Types of source

8.6m ID

1-T 3-Pole wiggler

Bend magnet

6.6m ID

x (µm) 108 175 44.2 29.6x’ (µrad) 4.6 14 63.1 16.9y (µm) 4.8 12.4 15.7 3.1

y’ (µrad) 1.7 0.62 0.63 2.6

NSLS-II Lattice Functions & Electron Beam sizes / divergences

Lattice Functions

Electron Beam Sizes & Divergences

Most challengingBeam stabilityRequirements= ~ 0.31 μm



NSLS-II SR RF BPM System – Performance Requirements*

Parameters/ Subsystems Conditions Standard RF BPM System Resolution RequirementVertical Horizontal

Single bunch, Single turn resolution (@ 378 kHz)

0.05 nC charge 500 μm rms 500 μm rms 5.0 nC charge 20 μm rms 20 μm rms

Single bunch stored beam resolution (0.017-200 Hz BW)

0.02 mA current 10 μm rms 10 μm rms2.0 mA current 1 μm rms 1 μm rms

50 mA *** to 500 mA Stored beam resolution – 20% to 100 % duty cycle

BPM ReceiverElectronics

Assuming no contribution from bunch/ fill pattern effects

**0.017 Hz to 200 Hz 0.2 μm rms 0.3 μm rms200 Hz to 2000 Hz 0.4 μm rms 0.6 μm rms**1 min to 8 hr drift 0.2 μm pk-pk 0.5 μm pk-pk

Bunch charge/ fill pattern effects only DC to 2000 Hz 0.2 μm rms 0.3 μm rmsMechanical motion limit at Pick-up electrodes assembly (ground & support combined)

Vibrations 50 Hz to 2000 Hz 10 nm rms 10 nm rms4 Hz to 50 Hz 25 nm rms 25 nm rms0.5 Hz to 4 Hz 200 nm rms 200 nm rms

Thermal **1 min to 8 hr 200 nm pk-pk

500 nm pk-pk

* Requirement values are preliminary - work in progress** ID BPM system resolution values will be smaller ( factor of ~ 0.5) *** @ 5 mA – 50 mA stored beam, BPM receiver resolution values will be worse (factor of ~2)

(Req. met - Test Data Later)



BPM Evaluation - Baseline Design

Baseline Design (one button/flange) Consists of one 10 mm dia. button w 34 mm flanges ~ 28 mm horizontal separation & ~ 25 mm vertical aperture Matlab Simulation input power level @ 500 mA= - 2 dBm (OK)

Sx =~ 0.12 / mm ; Sy =~ 0.04 / mm (low)

Electronic Resolution in frequency band 0.017 – 200 Hz

H-Resolution =~ 100 nm ; V-Resolution =~ 300 nm

Baseline Design (28x25)

SX=~0.12 SY=~0.04



BPM Evaluation - Proposed Design

Proposed Design

(two button/flange)

Consists of two ~7 mm dia. buttons on a single 50 mm dia. Flange; with ~16 mm H-separation (vertical aperture remains same - 25mm)

Two buttons on a flange reduces total flange counts & makes survey/ alignment process easier

7 mm button (over 10 mm) is also favored for beam heating issue

50

16

25

2

A

A



BPM Evaluation - Proposed Design (cntd)

Proposed Design (two button/flange) Matlab Simulation shows

input power level @ 500 mA = -8 dBm (OK)

Sx =~ 0.09 / mm ; Sy =~ 0.09 / mm (OK)

Electronic Resolution in 0.017 – 200 Hz BW

H-Resolution =~ 135 nm

V-Resolution =~ 135 nm (200 nm reqd)

Resolution vs Input Power

-8 dBm

Res

olut

ion

SX=~0.09 SY=~0.09



Flange Layout – 7mm buttons



RF BPM Button

Findings, recommendations and comments:

Button block cooling issues should be addressed, including block distortion and the possible compromise of Helicoflex flex gasket integrity due to beam heating from trapped modes (Diamond experience). A smaller button diameter should be considered to reduce button heating and impedance (look at the ALBA paper submitted to the 2007 DIPAC).

NSLS-II Accelerator Technical Review Instrumentation and Diagnostics

August 9-10, 2007Report of the Review Committee

submitted September 28, 2007

Button Heating



RF Button Heating Mini-Workshop at EPAC (June,2008)

Organized by Soleil/NSLS-II - attended by experts from NSLS- II, KEK, Soleil, Diamond, PEP-II, ESRF, PETRA-III, SLS, SPEAR3, Bergoz & Others.

Presentations from NSLS-II, Soleil, Diamond, ESRF Measured temperatures of connector pin on ambient side

in the range of 60oC @ ESRF in the range of 100oC @Diamond suggesting buttons themselves may be considerably hotter (~ several hundred oC)

Estimated power at Diamond (from both GdfidL and temperature measurements) is ~5W/button, distortions/ position drifts are large ~10 microns

Scaling to NSLS-II parameters suggests to do initial Ansys analysis with ~3W/button



RF Button Heating mini-Workshop at EPAC (June,2008) (cntd)

Agreement on mechanism of heating – hi Q trapped mode in transmission line formed by outer circumference of button and inner surface of housing.

Diamond results suggest - do initial Ansys analysis with 3W/button to get thermal distribution/distortion – this is in progress

Soleil simulations suggest - adjust button thickness and gap to wall to change transmission line impedance

Gdfidl simulation - Kloss factor as thickness 0.012 V/pc @ 2 mm; 0.007 V/pc @ 5mm

Repeat the analysis with “Microwave Studio” simulationOngoing communication/collaboration with other labs


ID BPM Button - Baseline Design

~70 mm

~10 mm

Baseline design provides adequate sensitivity – SX=0.26; SY=0.14 Detail button heating analysis needs to be done with NSLS-II beam Two configurations of ID BPMs are proposed

Normal configuration - uses a low thermal expansion stand for stability Alternate configuration – buttons mounted on ID chamber, when adequate space is not available for bellows, transitions and stand.

Established Design – used at APS & Elettra

Two 4 mm Dia buttonsHS = 10 mm

Flanges mounted on top & bottom of Small gap

Chamber


Sensitivity Optimization – Rotated Flange

Vertical sensitivity will be further optimized by rotating the 2-button flange, if needed

Effects of longitudinal displacement of buttons needs to be analyzed

Rotated Un-Rotated

Sensitivity vs H-separation



Calibrator Set-up

Confirm transfer function calculations

Use single wire to simulate beam current; mounted on two motor controlled assemblies.

Use two 34 mm dia. flanges; mount on a large flange to adjust H-separation by rotation

Explore interaction between beampipe modes and button resonance

Evaluate BPM electronics

Develop beam simulator – Possible Collaboration with SLAC

Evaluate position and fill pattern dependencies – critical for top off operation



ID-BPM Stable Support

10” Dia Carbon fiber composite stand limits thermal expansion to 20 nm/m/0.1oC

BPM assembly – has 3 invar rods for alignment small gap vertical aperture & 4 mm dia buttons for optimizing sensitivity Standard size flange at each end

Specification Total Thermal expansion < 100 nm R. Alforque



ID BPM Support Thermal Stability

Position Stability Requirement for User BPMs is 100nm vertical

Temperature stability spec for the tunnel is +/- 0.1C

Need to verify that support post meets spec

Build a fiducial structure using additional low TEC posts (next slide)

Thermally isolate the fiducial, and give it lots of mass ( ~ 1 week)

Thermally isolate the test post, use heaters to vary temperature ( ~ 1 hour)

Use capacitive and DVRT sensors to measure length variations

Status

DAQ, some position sensors, and some temperature sensors in house

POs for remaining position and temperature sensors have been written

Shop fabrication of the test stand is underway



~4

8”

~48” Notes:

1. All components to be wrapped with insulating blankets wherever possible

2. 3/16” sstl rods in tension will support the central tube

3. All materials sstl other than the carbon fiber tubes

Indicates Pt temp sensor Indicates TC temp sensor

ID-BPM Support Test Set-up

at both ends measure relative displacement due to temperature variation



RF BPM Electronics -Proposed Studies

• Long term stability (for centered and off-centered beams)• Measure dynamic range• Dependence on ambient temperature• Fill pattern dependence (including different envelopes)• Dependence on RF frequency• Effects of cable length mismatch• Noise spectrum• Explore for “dangerous” frequencies• Signal pre-processing • Establish acceptance test requirements



Stand for Stability Test for Libera Brilliance

Libera Brilliance

Attenuator

A B C D

4-waySplitter

Gated Oscillator

Func. Generator

Attenuator

Attenuator

Attenuator

system clock

machine clock

500 MHz

Reference 10 MHz

External Clock

Repeater

• RF frequency can be modified by external clock

• Chosen configuration provides phase locking between carrier and beam envelope

• Arbitrary waveform generator - provides amplitude or phase modulation/ trigger pulse modulation

• Temperature is monitored with platinum PT-100 probe using Digital Multi-meter



First Results from the Libera Tests – Meet Drift Spec.

TEMP~ 1 oC

HOR~ 200 nm

VERT~ 100 nm

TE

MP

HO

RV

ER

T

7 Hrs

Power level 6 dBm (0 dBm at each input)

80% fill (2 μs pulse duration with 2.62 μs pulse repetition rate)

Temperature Drift 200 nm /°C



Pinhole Camera with 3PW Source

3PW has higher magnetic field (1.14 T) than dipole. Shorter critical wavelength provides better spatial resolution. Large vertical β-function (21 m) gives large beam size (12.4 μ). Horizontal beam size is defined predominantly by energy spread (σE/E·η=170μ) rather than emittance (1nm·4.1m)½=64μ. Attenuator reduces heat load on elements and serves as high pass filter for synchrotron radiation.Estimation of resolution is done using MATLAB script.

Achievable resolution of 5.2 microns is sufficient for reliable measurement of vertical beam size (12.5 microns for 8 pm emittance)

Image of the beam is magnified by factor 5 and loss of resolution due to phosphor is of less importance)

Three-polewiggler

Bending magnet Al window

Attenuator TungstenPinhole

CdWO4 scintillator

Mirror

CameraL1=3 m L2=15 m



Near Term Plan

Complete detail RF button heating analysis Prototype two-button/flange BPM & test ID-BPM support procurement in process Design & build test set-up to measure support

thermal stability Integrate & test BPM calibrator set-up with computer control Develop program to evaluate/ compare BPM electronics



Summary

Location of bpms and diagnostics hardware have been identified

SR BPM resolution requirement table vs time scale in progress

New button design in progress for standard RF BPM

Heat issues are being addressed for standard & ID BPMs (RF)

ID-BPM support design is complete; Procurement is progress

ID-BPM support thermal test set-up designs in progress

ID-BPM calibration test set-up complete; Integration to follow

Pin-hole diagnostic beamline design analysis in progress

Near term plan has been identified



Acknowledgements

R. Alforque, A. Blednykh, A. Broadbent, P. Cameron, B. Dalesio, L. Doom, R. Heese, G. Ganetis, D. Hseuh, E. Johnson, S. Kramer, F. Lincoln, R. Meier, I. Pinayev, J. Rose. S. Ozaki, S. Krinsky, B. Mullany, V. Ravindranath, S. Sharma, J. Skaritika, T. Tanabe, T. Shaftan, W. Wildes, F. Willeke, L.Y. Yu.



Backup Slides



Diagnostics System Hardware Layout

Dipole (BM-A)

QL1Q

L2QL3

SL3

SL2

e-

Dipole (BM-B)

Short straight section – 11-ID

DCCT Stripline SCW

e-

~1 m

4 diagnostics hardware slots at 3 PW locations

Cell # 26-29



courtesy Alexei Blednykh



0 5 10 15 20 25 300

1

2

3

4

5

6x 10-3

s, mm

lo

ss,

V/p

C

th=2mm

th=5mm

-40 -20 0 20 40 60-0.02

-0.01

0

0.01

0.02

s, mm

Wlo

ng,

V

th=2mm

th=5mm

Ploss, W

th=2mm th=5mm

loss, V/pCs=4.5mm

3.4 (h=1000)6.8 (h=500)

1.6 (h=1000)3.3 (h=500)

loss, V/pCs=6.5mm

1 (h=1000)2 (h=500)

0.5 (h=1000)0.9 (h=500)

loss, V/pCs=30mm

0.03 (h=1000)0.07 (h=500)

0.01 (h=1000)0.03 (h=500)

loss, V/pC

th=2mm th=5mm

s=4.5mm 5.2e-3 2.5e-3

s=6.5mm 1.5e-3 0.7e-3

s=30mm 0.05e-3 0.02e-3

Iav=500mA, T0=2.6e-6m

Loss factor and Power Loss



Partial Compilation of Relevant Parameters

color code: yellow – NSLS-II options red – danger of physical damage purple – thermal distortion due to heating

NSLS-II Accelerator System Advisory Committee Review Diagnostics Design and R&D

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