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VIBRATING WIRE SENSORS FOR BEAM INSTRUMENTATION

Suren Arutunian

Yerevan Physics Institute

Yerevan Physics Institute S.Arutunian, VIBRATING WIRE SENSORS FOR BEAM INSTRUMENTATIONBIW 2008, Lake Tahoe, USA

Conceptual idea



Vibrating wire scanner -dream of 1994

Vibrating wire scanner test in lab [Arutunian et. al., PAC (March 29 -April 2, 1999, New York City)]

Simple theory: why VWS sensitivity is extremely high?

ρσ•= lF 1

ρσl

llEFF ∆•=∆ σ2/

TEFF S∆•−=∆ ασ2/

GPaE 200=MPastrenghttensile 800500−=−<<σ

E


material densitywire strainwire lengthmodulus of elasticity

500/ ≈σE

Single wire VWS (DESY, PETRA)

1- wire2- clips3, 4 – magnet poles5 – support6, 7 – fastening details

Oscillations excitation and frequency measurement unit


Generator is assembled on the base of fast operational amplifier allows to maintain the generation just on the wire natural frequency resonance

Wire is included into positive feedback circuit

Electronic circuit test (I.Vasiniuk)

Frequency measurement algorithm

Time t1 – wire periods counting start

Time t2 – wire periods counting end

T_wire – wire oscillation periodT_q – quartz oscillation periodF_wire=F_q*N_wire/N_qt2-t1=gate in range 100 ms-30 s

0.163051500.1

Resolution, mHzgate, s

Measurement resolution at F_wire about 5000 Hz and F_q=1.0000 MHz

2 wires VWS long time run in laboratory environment

-0.15

-0.1

-0.05

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

06.10.2007 11:30 06.10.2007 17:30 06.10.2007 23:30 07.10.2007 5:30 07.10.2007 11:3029.86

29.88

29.9

29.92

29.94

29.96

29.98

30

30.02

30.04

30.06

dF_A(Hz)dF_B(Hz)T (°C)

Absolute deviations for24 hours:

dF_A0.03 Hz

dF_B0.02 Hz

T0.01 0C

10 wires VWS long time run in laboratory environment

0.008100.00690.00780.04770.00860.01350.01040.01030.03620.0171

10 wires VWM absolute deviations for 36 hours, Hz

-0.1

-0.08

-0.06

-0.04

-0.02

0

0.02

0.04

0.06

0.08

0.1

17.11.20070:00

17.11.20076:00

17.11.200712:00

17.11.200718:00

18.11.20070:00

18.11.20076:00

18.11.200712:00

Time

dF, H

z

dF_1dF_3dF_4dF_5dF_6dF_8dF_9dF_10

Thermostabilization at 30 0C with Platinum resistance thermometer

Frequencies resonant capture

3646

3648

3650

3652

3654

3656

3658

3660

3662

3664

3666

27.08.04 12:00 28.08.04 12:00 29.08.04 12:00 30.08.04 12:00 31.08.04 12:00Time

F, H

z

21

21.3

21.6

21.9

22.2

22.5

22.8

23.1

23.4

23.7

24

T_k

ty, 0

C

F1(Hz) F2(Hz) T(0C)

-0.005

-0.004

-0.003

-0.002

-0.001

0

0.001

0.002

0.003

0.004

0.005

27.08.2004 12:00 28.08.2004 12:00 29.08.2004 12:00 30.08.2004 12:00 31.08.2004 12:00

TimeF1

-F2,

Hz

-1

0

1

2

3

4

5

6

7

8

9

F1-F

2, H

z

1

2


Each frequency was measured by separate electronic unit with proper quartz oscillator.Measurement gate 30 s ( resolution 1 mHz )

Multiwire sensor wires thermal coupling in air

0.2470.0900.051-0.019

0.0900.2650.101-0.029

0.0510.0990.283-0.050

-----

0.0190.0310.052-0.255

wire 5 wire 4 wire 3 wire 2 wire 1

0

0.2

0.4

0.6

0.8

1

1.2

0 0.5 1 1.5 2distance, mm

ratio


VWS housing

VWS wires

Heat transfers

VWS wires were fed by aDC current (about 10 mA)

Wires overheatings when outermost wire was fed by DC current

Multiwire sensor wires thermal coupling in air

heat coupling equations

)52(25)42(24)32(23222)12(122 TTTTTTTTTQ −+−+−++−= ααααα

)53(35)43(34333)23(23)13(133 TTTTTTTTTQ −+−++−+−= ααααα

)54(45444)34(34)24(24)14(144 TTTTTTTTTQ −++−+−+−= ααααα

555)45(45)35(35)25(25)15(155 TTTTTTTTTQ ααααα +−+−+−+−=

)51(15)41(14)31(13)21(121111 TTTTTTTTTQ −+−+−+−+= ααααα


iT wire with index i overheating

Frequency dependence on ambient temperature

-40

-35

-30

-25

-20

-15

-10

-5

0

5

02.11.20070:00

03.11.20070:00

04.11.20070:00

05.11.20070:00

06.11.20070:00

07.11.20070:00

08.11.20070:00

Time

DF,

Hz

0

10

20

30

40

50

60

70

80

T, 0

C

DF1, HzDF2, HzDF3, HzDF4, HzDF5, HzT(0 C)

-40

-35

-30

-25

-20

-15

-10

-5

0

30 35 40 45 50 55 60 65 70

Ambient temperature, 0C

DF,

Hz

DF1, HzDF2, HzDF3, HzDF4, HzDF5, Hz

-8.35E+03-7.35E+03 -7.47E+03 -8.73E+03 -5.50E+03 dF2/dT, Hz2/K

54321

Compare with -3.38E+05 Hz^2/K for single wire


VWM005 behavior immediately after sensor assembling

Technical characteristics

0.151.80.2620.2response time, s-2.0-26.4-9.3-779.6DF/DQ, Hz/mW-8.8-8.8-40.2-40.2DF/DTmean, Hz/K at F0 = 4200 Hz0.233.00.2319.4DTmean/DQ, K/mW

TungstenAir

TungstenVacuum

A316Air

A316Vacuum

Material, conditions

Technical characteristics of 5 wire VWM in case of usage in air resolution of frequency measurement is 0.01 Hzmeasurement accuracy (1 hour) ± 0.01 Hz (± 0.00025 K)

(24 hour) ± 0.04 Hz (± 0.001 K )response time 0.26 sdeposited on the wire power ± 1 µW (1 hour) ± 4 µW (24 hour) Nonlinearity of the pickup in operational range 0-100 mW is 0.01 %


Electron beam


VWS installing in 50 MeVInjector of Yerevan Synchrotron(N.Dobrovolsky, M.Mailian)

VWM incut intovacuum chamber

Electron beam

-0,5

0,0

0,5

1,0

1,5

2,0

25 27 29 31 33 35 37

Wire horizontal position, mmB

eam

cur

rent

den

sity

in h

oriz

onta

l dire

ctio

n, n

A/m

m


Scan of the electron beam at the Injector of Yerevan Synchrotron with an average current of about 10 nA (after collimation) and an electron energy of 50 MeV

VWS mounted on the vacuum below with 1 µm step motor feed

Proton beam


VWS for PETRA experiment, one beryl bronze wire of diameter 90 µm

VWS installing into PETRA proton bypass(R.Boespflug, left and K.Wittenburg)

VWS mounted on tube with below and step motor

Proton beam

4870

4871

4872

4873

4874

4875

4876

4877

4878

4879

4880

21:59:00 22:01:00 22:03:00 22:05:00 22:07:00 22:09:00Time

Freq

uenc

y, H

z

0

10

20

30

40

50

VW

S po

sitio

n, m

m;

PM1

and

PM2

coun

tings

;B

eam

cur

rent

, mA

11

23

4

5


PETRA proton beam parameters E=15 GeV, I=15 mA sigmax = 0.6 cm, sigmaz = 0.5 cm

1- VWS frequency, 2 – proton current, 3 – VWS position, 4,5 - scintillator-photomultiplierpickup signals (PM).Full scan – 20 mmPM1 began to increase beyond the position 9.3 mm,VWS – immediately

Ion beam

5125.50

5125.55

5125.60

5125.65

5125.70

5125.75

5125.80

5125.85

5125.90

5125.95

5126.00

5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45

Time, s

Freq

uenc

y, H

z


Energo-mass-analyzer EMAL-2 a device with laser source of ions for mass-spectral analysis of solids. Fe ion beam with current about 1 nA and energy 20 keV passes through the gap with sizes 2 mm × 5.5 mm and fall on the wire

Approximately 16 pA of beam current interacted with the wire, frequency decrement about 0.15 Hz

Laser beam

Laser beam scan experiment layout. 1-Commbox measurement unit, 2 – measuring microscope, 3 – stepper motor feed system, 4 –stepper motor control board, 5 - laser, 6 - VWM


Laser beam

4212.7

4212.8

4212.9

4213

4213.1

4213.2

4213.3

0 1 2 3 4 5 6 7 8Transverse coordinate, mm

Freq

uenc

y 1,

Hz

3975.4

3975.5

3975.6

3975.7

3975.8

3975.9

3976

Freq

uenc

y 2,

Hz

F2(Hz)F1(Hz)


Sensitivity 20 Hz/K Frequency accuracy 0.01 HzTemperature resolution 5 ×1E-4 KLaser radiation power density resolution

in air 3×1E-6 W/mm^2

in vacuum 5×1E-8 W/mm^2

APS 2007

Beamline SBC-CAT-19-ID: Source Undulator AEnergy Range 6.5-19.5 keVFlux (photons/sec)1.4 x 10^13 @ 12 keV

VWS installing in vacuum test chamber of beamline(G.Rosenbaum)

APS 2007


Alignment procedure to assure that both wires were symmetrically placed above and below the midplane with a clear line of sight to the source (G.Decker)

VWS mounted on the water-cooled plates

Beryllium filter

APS 2007


Data collected at a 1-Hz sample rate during a scan of the particle beam’s vertical angle in range 100 microradians with 5 microradian steps

VWM data corrected for thermal drift and beam current decay

Plot of ∆TD shifted by 1.730 mm

APS 2007


A very successful shift (G.Rosenbaum, M.Mailinan, S.Arutunian, G.Decker)

Total of 7 mm ofBeryllium was placed in the beam path, both to limit thepower striking the wires and to assure that only hard x-rayswere being detected

Incorporation of such a device into the design of water-cooled beamline apertures ( “smart aperture”, G.Decker ) is another interesting concept

APS 2008


Five-wires VWM005 details:(1) sensor, (2) surface of the vertical plate, (3) rectangular window for synchrotron beam accept with VWM005 aperture, (4) number of the sensor, (5) numbers of the first and fifth wires, At one side of the sensor all wires are connected together (6), other wires are assembled in a harness (7). The wires are shifted along the line AA

APS 2008


Main view of VWM005 mounting on the flange

VWM is mounted on the 6 inch flange

APS 2008

1.E-121.E-111.E-101.E-091.E-081.E-071.E-061.E-051.E-041.E-031.E-021.E-011.E+00

0.E+00 1.E+05 2.E+05 3.E+05 4.E+05 5.E+05 6.E+05

Photon Energy, eV

Nor

mal

ized

spec

tral

dis

trib

utio

n

Y Y_Cu Y_wire

Integral=1Integral=4.24E-3Integral=1.14E-5

P_initial=99.1 WNormalized spectral distribution of initial synchrotron radiation (Y), passed through the Cu flange (Y_Cu) and deposited into the wire (Y_wire). Spectral maximums for Y_Cu and Y_wire are about 100 keV

APS 2008

-0.6-0.4-0.20.00.20.40.60.81.01.21.41.6

24.01.2008 9:00 24.01.200815:00

24.01.200821:00

25.01.2008 3:00 25.01.2008 9:00

Time

DT

1, K

-0.2

0.0

0.2

0.4

0.6

13:30 14:00

VWM data dependence on the ambient T. Synchrotron radiation do not touch the wires of VWM. Data show the change of the flange temperature during APS operation

APS 2008

0

0.02

0.04

0.06

0.08

0.1

0.12

82 84 86 88 90 92 94 96

Time, min

Wir

es o

verh

eatin

g, K

d T_1d T_2d T_3d T_4d T_5


Scan result presented by wire overheating temperatures.Electron beam was scanned vertically through a range of 300 microradians with 125 steps

VWM when the electron beam angle was scanned vertically through a range of 300 microradians with 125 stepsElectron beam scanned vertically from minus 350 to minus 650 microradian angle with 125 steps

Profiles asymmetries arise from mentioned above wires thermal coupling and some inequality placement of wires relative to sensor housing

APS 2008

-0.05

0

0.05

0.1

0.15

0.2

380 430 480 530 580

Steering angle, microrad

SR b

eam

pro

file,

arb

itrar

y un

its

Q1Q2Q3Q4Q5

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0.18

-60 -50 -40 -30 -20 -10 0 10 20 30 40 50 60

Steering angle, microradSR

bea

m p

rofil

e, a

rbitr

ary

units


United profile from all wires (curves are shifted according to value of maximum)

Using a statistical data treatment, the heat coupling coefficients were found and accordingly the profiles of the source were recovered

Discussion1. Vibrating wire sensors can be used for many types of beam

diagnostics because only a small amount of heat transfer from the measured object to wire is needed. VWS can be successfully applied to electron, proton, ion, photon and neutron beam monitoring

2. Special tasks: weak beam instrumentation, beam halo and tails monitoring

3. Property to measure very hard spectral component permits to separate the radiation from insertion devices and to cut unwanted contributions from other accelerator sources

4. Recent application of the VWS in air has allowed a dramatic reduction in response time, together with a reduction in system cost by a large factor

5. So called “smart aperture” concept (G.Decker)

Acknowlegments

Author is grateful to all his co-authors with whom he worked many years. Many thanks to the YerPhI, PETRA and APS ANL stuff for their friendly help during the experiments. Special thanks to R.Reetz and J.Bergoz for permanent interest and essential support

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