lcls magnet damage management heinz-dieter nuhn, slac / lcls june 19, 2008
DESCRIPTION
LCLS Magnet Damage Management Heinz-Dieter Nuhn, SLAC / LCLS June 19, 2008. Present Strategies for LCLS Beam Loss Monitoring Review of the Individual Magnet Irradiation Test T-493 Results of Damage Measurements Plans for follow-up Mini-Undulator Irradiation Test. - PowerPoint PPT PresentationTRANSCRIPT
1June 19, 2008 Heinz-Dieter Nuhn, SLAC / LCLSLCLS Magnet Damage Management [email protected]
LCLS Magnet Damage ManagementHeinz-Dieter Nuhn, SLAC / LCLS
June 19, 2008
Present Strategies for LCLS Beam Loss Monitoring Review of the Individual Magnet Irradiation Test T-493 Results of Damage Measurements Plans for follow-up Mini-Undulator Irradiation Test
Present Strategies for LCLS Beam Loss Monitoring Review of the Individual Magnet Irradiation Test T-493 Results of Damage Measurements Plans for follow-up Mini-Undulator Irradiation Test
2June 19, 2008 Heinz-Dieter Nuhn, SLAC / LCLSLCLS Magnet Damage Management [email protected]
LCLS Beam Loss Monitors (BLMs) Strategies
Radiation protection of the permanent magnet blocks is very important.
Funds have been limited and efforts needed to be focused to minimize costs.
A Physics Requirement Document, PRD 1.4-005 exists, defining the minimum requirements for the Beam Loss Monitors.
The damage estimates are based on published measurement results and a in-house simulations.
Radiation protection of the permanent magnet blocks is very important.
Funds have been limited and efforts needed to be focused to minimize costs.
A Physics Requirement Document, PRD 1.4-005 exists, defining the minimum requirements for the Beam Loss Monitors.
The damage estimates are based on published measurement results and a in-house simulations.
3June 19, 2008 Heinz-Dieter Nuhn, SLAC / LCLSLCLS Magnet Damage Management [email protected]
Estimated Radiation-Based Magnet Damage
The loss of magnetization caused by a given amount of deposited radiation has been estimated by Alderman et al. [i] in 2000. Their results imply that a 0.01% loss in magnetization occurs after exposure to a fast-neutron fluence of 1011 n/cm2.A more recent report by Sasaki et al. [ii] challenges fast neutron fluence as damaging factor and, instead, proposes photons and electrons but does not provide a relation between integrated dose and damage.
[i] J. Alderman, et. A., Radiation Induced Demagnetization of Nd-Fe-B Permanent Magnets, Advanced Photon Source Report LS-290 (2001)
[ii] S. Sasaki, et al, Radiation Damage to Advanced Photon Source Undulators, Proceedings PAC2005.
The loss of magnetization caused by a given amount of deposited radiation has been estimated by Alderman et al. [i] in 2000. Their results imply that a 0.01% loss in magnetization occurs after exposure to a fast-neutron fluence of 1011 n/cm2.A more recent report by Sasaki et al. [ii] challenges fast neutron fluence as damaging factor and, instead, proposes photons and electrons but does not provide a relation between integrated dose and damage.
[i] J. Alderman, et. A., Radiation Induced Demagnetization of Nd-Fe-B Permanent Magnets, Advanced Photon Source Report LS-290 (2001)
[ii] S. Sasaki, et al, Radiation Damage to Advanced Photon Source Undulators, Proceedings PAC2005.
4June 19, 2008 Heinz-Dieter Nuhn, SLAC / LCLSLCLS Magnet Damage Management [email protected]
Estimate of Neutron Fluences from LCLS e- Beam
The radiation deposited in the permanent magnets blocks of the LCLS undulator, when a single electron (e-) strikes a 100-µm carbon foil upstream of the first undulator, has been simulated by A. Fasso [iii].The simulations predict a peak total dose of 1.0×10-9 rad/e- including a neutron (n) fluence of 1.8×10-4 n/cm2/e-, which translates into 1.8×105 n/cm2 for each rad of absorbed energy.These numbers are based on peak damage results and should therefore be considered as worst case estimates.
[iii] A. Fasso, Dose Absorbed in LCLS Undulator Magnets, I. Effect of a 100 µm Diamond Profile Monitor, RP-05-05, May 2005.
The radiation deposited in the permanent magnets blocks of the LCLS undulator, when a single electron (e-) strikes a 100-µm carbon foil upstream of the first undulator, has been simulated by A. Fasso [iii].The simulations predict a peak total dose of 1.0×10-9 rad/e- including a neutron (n) fluence of 1.8×10-4 n/cm2/e-, which translates into 1.8×105 n/cm2 for each rad of absorbed energy.These numbers are based on peak damage results and should therefore be considered as worst case estimates.
[iii] A. Fasso, Dose Absorbed in LCLS Undulator Magnets, I. Effect of a 100 µm Diamond Profile Monitor, RP-05-05, May 2005.
5June 19, 2008 Heinz-Dieter Nuhn, SLAC / LCLSLCLS Magnet Damage Management [email protected]
Simulated Neutron Fluences for LCLS e- Beam on C Foil
Simulated neutron fluences in the LCLS undulator magnets (upper jaw) from a single electron hitting a 100-µm-thick carbon foil upstream of the first undulator.
Maximum Level is
1.8×10-4 n/cm2/e-
Simulated neutron fluences in the LCLS undulator magnets (upper jaw) from a single electron hitting a 100-µm-thick carbon foil upstream of the first undulator.
Maximum Level is
1.8×10-4 n/cm2/e-
6June 19, 2008 Heinz-Dieter Nuhn, SLAC / LCLSLCLS Magnet Damage Management [email protected]
Total Dose from LCLS e- Beam on C Foil
Corresponding maximum deposited dose.
Maximum Level is
1.0×10-9 rad/e-
Corresponding maximum deposited dose.
Maximum Level is
1.0×10-9 rad/e-
7June 19, 2008 Heinz-Dieter Nuhn, SLAC / LCLSLCLS Magnet Damage Management [email protected]
Radiation Limit Estimates
Neutron Fluence for 0.01 % magnet damage from Alderman et al. 1011 n/cm2
Maximum neutron fluence in LCLS magnets from hit on 100 micron C foil from Fasso 1.8×10-4 n/cm2/e-
Maximum total dose in LCLS magnets from hit on 100 micron C foil from Fasso 1.0×10-9 rad/e-
Ratio of neutron fluence per total dose 1.8×105 n/cm2/rad
Maximum total dose in LCLS magnets for 0.01 % damage 5.5×105 rad
Nominal LCLS lifetime 20 years
Number of seconds in 20 years 6.3×108 s
Maximum average permissible energy deposit per magnet 0.88 mrad/s
Corresponding per pulse dose limit during 120 Hz operation 7.3 µrad/pulse
~0.01 mrad/pulse @ 120 Hz; ~1 mrad/s
8June 19, 2008 Heinz-Dieter Nuhn, SLAC / LCLSLCLS Magnet Damage Management [email protected]
Neutral; K=3.4881; x= 0.0 mm Neutral; K=3.4881; x= 0.0 mmNeutral; K=3.4881; x= 0.0 mm
Undulator Roll-Away and K Adjustment Function
First; K=3.5000; x=-4.0 mm Roll-Out; K=0.0000; x=+80.0 mm
Horizontal SlideHorizontal Slide
Pole Center LinePole Center Line Vacuum ChamberVacuum Chamber
9June 19, 2008 Heinz-Dieter Nuhn, SLAC / LCLSLCLS Magnet Damage Management [email protected]
Maximum Estimated Radiation Dose from BFW Operation
Maximum neutron fluence in magnets of the last undulator due to BFW hit;
based on Fasso simulations; scaled to
Total Charge: 1 nC; Wire Material: C; Wire Diameter 40 µm; RMS Beam radius 37 µm;
1.5×105 n/cm2/pulse
Corresponding radiation dose 1 rad/pulse
Ratio of peak BFW dose to maximum average dose limit 105
Radiation dose received by last undulator by 33 full x and y scans 100 rad
Maximum number of full BFW scans to reach 20 % a maximum dose budget 103
All
Un
du
lato
rs R
oll
ed
-In
Maximum neutron fluence in magnets of an undulator on same girder due to BFW hit;
based on Fasso simulations; scaled to
Total Charge: 1 nC; Wire Material: C; Wire Diameter 40 µm; RMS Beam radius 37 µm;
1.5×103 n/cm2/pulse
Corresponding radiation dose 10 mrad/pulse
Ratio of peak BFW dose to maximum average dose limit 103
Radiation dose received by last undulator by 33 full x and y scans 1 rad
Maximum number of full BFW scans to reach 20 % a maximum dose budget 105
Un
du
lato
rs o
n D
S G
ird
ers
Ro
lle
d-O
ut
(
1/1
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)
The small amount of scans expected, can be ignored for damage purposes; but might require MPS exception.
10June 19, 2008 Heinz-Dieter Nuhn, SLAC / LCLSLCLS Magnet Damage Management [email protected]
Radiation Sources
Possible reasons for generating elevated levels of radiation areElectron Beam Steering Errors
Will be caught and will lead to beam abort.Unintentional Insertion of Material into Beam Path
Will be caught and will lead to beam abort.Intentional Insertion of Material into Beam Path
BFW operationIs expected to produce the highest levels. May only be allowable when all down-stream undulators are rolled-out and beam charge is reduced to minimum.
Screen insertionMay only be allowable when all undulators are rolled-out and beam charge is reduced to minimum.
Background Radiation from Upstream Sources including Tune-Up DumpExpected to be sufficiently suppressed by PCMUON collimator.
Beam HaloExpected to be sufficiently suppressed through upstream collimation system.May require halo detection system.
11June 19, 2008 Heinz-Dieter Nuhn, SLAC / LCLSLCLS Magnet Damage Management [email protected]
General Requirements
One BLM device will be mounted upstream of each Undulator Segment The BLM will provide a digital value proportional to the amount of energy deposited in the device for each electron bunch.The monitor shall be able to detect and measure (with a precision of better than 25%) radiation levels corresponding to magnet dose levels as low as 10 µrad/pulse [0.1 µGy/pulse] and up to the maximum expected level of 10 mrad/pulse [100 µGy/pulse].The monitor needs to be designed to withstand the highest expected radiation levels of 1 rad/pulse without damage. The radiation level received from each individual electron bunch needs to be reported after the passage of that bunch to allow the MPS to trip the beam before the next bunch at 120 Hz.
NOT FULLY REALIZED
12June 19, 2008 Heinz-Dieter Nuhn, SLAC / LCLSLCLS Magnet Damage Management [email protected]
Monitor Requirements
Each BLM device will be able to measure the total amount of absorbed dose covering the full area in front of the undulator magnets.
Each BLM device will be calibrated based on the radiation generated by the interaction of a well known beam with the BFW devices.
The calibration geometry will be simulated using FLUKA and MARS to obtain the calibration factors, i.e., the ratio between the maximum estimated damage in a magnet and the voltage produced by each BLM device.
NOT FULLY REALIZED
13June 19, 2008 Heinz-Dieter Nuhn, SLAC / LCLSLCLS Magnet Damage Management [email protected]
Beam Loss Monitor Area Coverage
Main purpose of BLM is the protection of undulator magnet blocks. Less damage expected when segments are rolled-out.One BLM will be positioned in front of each segment.Its active area will be able to cover the full horizontal width of the magnet blocksTwo options for BLM x positions will be implemented to be activated by a local hardware switch:
(a) The BLM will be moved with the segment to keep the active BLM area at a fixed relation to the magnet blocks.(b) The BLM will stay centered on the beam axis to allow radiation level estimates in roll-out position.
Main purpose of BLM is the protection of undulator magnet blocks. Less damage expected when segments are rolled-out.One BLM will be positioned in front of each segment.Its active area will be able to cover the full horizontal width of the magnet blocksTwo options for BLM x positions will be implemented to be activated by a local hardware switch:
(a) The BLM will be moved with the segment to keep the active BLM area at a fixed relation to the magnet blocks.(b) The BLM will stay centered on the beam axis to allow radiation level estimates in roll-out position.
NOT FULLY REALIZED
14June 19, 2008 Heinz-Dieter Nuhn, SLAC / LCLSLCLS Magnet Damage Management [email protected]
BLM Purpose
The BLM will be used for two purposesA: Inhibit bunches following an “above-threshold” radiation event.
B: Keep track of the accumulated exposure of the magnets in each undulator.
Purpose A is of highest priority. It will be integrated into the Machine Protection System (MPS) and requires only limited dynamic range from the detectors.
Purpose B is desirable for understanding long-term magnet damage in combination with the undulator exchange program but requires a large dynamic range for the radiation detectors (order 106) and much more sophisticated diagnostics hard and software.
The BLM will be used for two purposesA: Inhibit bunches following an “above-threshold” radiation event.
B: Keep track of the accumulated exposure of the magnets in each undulator.
Purpose A is of highest priority. It will be integrated into the Machine Protection System (MPS) and requires only limited dynamic range from the detectors.
Purpose B is desirable for understanding long-term magnet damage in combination with the undulator exchange program but requires a large dynamic range for the radiation detectors (order 106) and much more sophisticated diagnostics hard and software.
15June 19, 2008 Heinz-Dieter Nuhn, SLAC / LCLSLCLS Magnet Damage Management [email protected]
ANL Beam Loss Monitor Design
Courtesy of W. Berg, ANLCourtesy of W. Berg, ANL
Rendering of DetectorRendering of Detector
BLM Mounted on BFW in Front of Undulator SegmentBLM Mounted on BFW in Front of Undulator Segment
Beam
A total of 5 BLM deviceswill be installed.
16June 19, 2008 Heinz-Dieter Nuhn, SLAC / LCLSLCLS Magnet Damage Management [email protected]
Plan View of Short Drift
Beam Loss MonitorBeam Loss Monitor
Undulators SegmentsUndulators Segments
QuadrupoleQuadrupole
BPMBPM
BFWBFW
Beam Direction
17June 19, 2008 Heinz-Dieter Nuhn, SLAC / LCLSLCLS Magnet Damage Management [email protected]
Additional Loss Monitors
Other Radiation Monitoring DevicesDosimeters
Located at each undulator. Routinely replaced and evaluated.
Segmented Long Ion ChambersInvestigated
(Quartz)-FibersInvestigated
Non-Radiative Loss DetectorsPair of Charge Monitors (Toroids)
One upstream and one downstream of the undulator lineUsed in comparator arrangement to detect losses of a few percent
Electron Beam Position Monitors (BPMs)Continuously calculate trajectory and detect out-of-range situations
Quadrupole Positions and Corrector Power Supply ReadbacksUse deviation from setpointsEstimate accumulated kicks to backup calculations based on BPMs.
18June 19, 2008 Heinz-Dieter Nuhn, SLAC / LCLSLCLS Magnet Damage Management [email protected]
LCLS Undulator Irradiation Experiment (T-493)
The LCLS electron beam is stopped in a copper dump, and 9 samples of magnet material are positioned at different distances from the dump.
The layout to achieve a range of doses is calculated using FLUKA.
The radiation absorbed will be measured by dosimeters.
Magnetization will be measured before and after exposure.
The integrated beam current will be needed to be recorded to 10%.
The LCLS electron beam is stopped in a copper dump, and 9 samples of magnet material are positioned at different distances from the dump.
The layout to achieve a range of doses is calculated using FLUKA.
The radiation absorbed will be measured by dosimeters.
Magnetization will be measured before and after exposure.
The integrated beam current will be needed to be recorded to 10%.
19June 19, 2008 Heinz-Dieter Nuhn, SLAC / LCLSLCLS Magnet Damage Management [email protected]
Linac Coherent Light Source
Near Hall
Far Hall
SLAC LINAC
Undulator Tunnel
Injector
Endstation A
T-493T-493
20June 19, 2008 Heinz-Dieter Nuhn, SLAC / LCLSLCLS Magnet Damage Management [email protected]
T-493 Components installed
ESA Beamline with copper cylinder and magnet blocks.
Copper target for 13.7 GeV e- Beam.
Diameter: 4 inches
Length: 10 inches
Dosimeters positioned at in the vicinity of each block.
[See presentation by Johannes Bauer]
ESA Beamline with copper cylinder and magnet blocks.
Copper target for 13.7 GeV e- Beam.
Diameter: 4 inches
Length: 10 inches
Dosimeters positioned at in the vicinity of each block.
[See presentation by Johannes Bauer]
Photo courtesy of J. BauerPhoto courtesy of J. Bauer
BEAM
21June 19, 2008 Heinz-Dieter Nuhn, SLAC / LCLSLCLS Magnet Damage Management [email protected]
Magnet Block Assembly
Straight-ahead mounting fixture on work bench with four magnet blocks (viewed in the direction of the beam.)
Straight-ahead mounting fixture on work bench with four magnet blocks (viewed in the direction of the beam.)
22June 19, 2008 Heinz-Dieter Nuhn, SLAC / LCLSLCLS Magnet Damage Management [email protected]
Mounted Magnet Block Next to Heat Shield
Magnet block mounted next to heat shield.Magnet block mounted next to heat shield.Mounting fixture with magnet for first forward position with heat shield.
Mounting fixture with magnet for first forward position with heat shield.
23June 19, 2008 Heinz-Dieter Nuhn, SLAC / LCLSLCLS Magnet Damage Management [email protected]
ANL Delivery of 12 LCLS Undulator Magnet Blocks
Photo courtesy of S. AndersonPhoto courtesy of S. Anderson
Material: Ne2Fe14B
Block Thickness: 9 mm
Block Height: 56.5 mm
Block Width: 66 mm
Material Density: 7.4 g/cm3
Block Volume: 33.6 cm3
Block Mass: 248.4 g
Curie Point: 310 °C
Material: Ne2Fe14B
Block Thickness: 9 mm
Block Height: 56.5 mm
Block Width: 66 mm
Material Density: 7.4 g/cm3
Block Volume: 33.6 cm3
Block Mass: 248.4 g
Curie Point: 310 °C
24June 19, 2008 Heinz-Dieter Nuhn, SLAC / LCLSLCLS Magnet Damage Management [email protected]
Pre-Irradiation Magnetic Moment Measurements
The table shows the results of the measurement of magnetic moments for one of the magnet blocks (Serial No. 00659) as an example.
The Magnetic Moments are measured with a Helmholtz-Coil.
All magnetic measurements have been carried out by Scott Anderson.
The table shows the results of the measurement of magnetic moments for one of the magnet blocks (Serial No. 00659) as an example.
The Magnetic Moments are measured with a Helmholtz-Coil.
All magnetic measurements have been carried out by Scott Anderson.
25June 19, 2008 Heinz-Dieter Nuhn, SLAC / LCLSLCLS Magnet Damage Management [email protected]
Magnet Block Assembly (Top View)
Beam Direction
Copper Cylinder
Magnet Blocks
rz
Top View
Heat Shield
4 Magnet blocks in forward direction5 Magnet blocks in transverse direction
3 Magnet blocks kept for reference
M4M3M2M1
M8
M5
M6
M7
M9
26June 19, 2008 Heinz-Dieter Nuhn, SLAC / LCLSLCLS Magnet Damage Management [email protected]
Magnet Block Assembly (View in Beam Directions)
yr
View in Beam Direction
Heat Shield
Copper Cylinder
Magnet Blocks
M1-M4M7M8 M6M9
M5
27June 19, 2008 Heinz-Dieter Nuhn, SLAC / LCLSLCLS Magnet Damage Management [email protected]
Experiment T-493 Shift Records
Magnet Irradiation Experiment T-493 ran for 38 shifts from7/27-8/09/2007
Magnet Irradiation Experiment T-493 ran for 38 shifts from7/27-8/09/2007
28June 19, 2008 Heinz-Dieter Nuhn, SLAC / LCLSLCLS Magnet Damage Management [email protected]
Delivered Power
Delivered power levels alternated between about 125 W during Day and Swing Shifts and 185 W during Owl Shifts.During Day and Swing Shifts the experiment ran parasitically with LCLS commissioning.
Delivered power levels alternated between about 125 W during Day and Swing Shifts and 185 W during Owl Shifts.During Day and Swing Shifts the experiment ran parasitically with LCLS commissioning.
29June 19, 2008 Heinz-Dieter Nuhn, SLAC / LCLSLCLS Magnet Damage Management [email protected]
Tunnel Temperature Profile
The temperature in the ESA tunnel stayed between 23-24.6°C during the entire 12-day data collection period.The plot shows diurnal cycle fluctuations.
The temperature in the ESA tunnel stayed between 23-24.6°C during the entire 12-day data collection period.The plot shows diurnal cycle fluctuations.
30June 19, 2008 Heinz-Dieter Nuhn, SLAC / LCLSLCLS Magnet Damage Management [email protected]
Magnetic Moment Evaluations: Results Summary
Shown are parameters for the 9 irradiated magnets and the Cu targetthe estimated neutron fluence and dose levelspeak power levelstemperature estimates
The last two columns contain the results of the magnets’ demagnetization measurements.
Shown are parameters for the 9 irradiated magnets and the Cu targetthe estimated neutron fluence and dose levelspeak power levelstemperature estimates
The last two columns contain the results of the magnets’ demagnetization measurements.
31June 19, 2008 Heinz-Dieter Nuhn, SLAC / LCLSLCLS Magnet Damage Management [email protected]
Detailed FLUKA model of the experiment
13.7 GeV electron beam impinging on the copper dump
Computation of total dose, electromagnetic dose, neutron energy spectra
Quantity scored using a binning identical to the one used for the mapping of the magnetization loss
BeamM3 M2
M5
M4
M6M7
M1
M8M9
Courtesy of J. Vollaire, SLAC Courtesy of J. Vollaire, SLAC
32June 19, 2008 Heinz-Dieter Nuhn, SLAC / LCLSLCLS Magnet Damage Management [email protected]
Damage Gradients
M3
M1
M2
M4 M3
M1
M2
M4
Threshold Estimates for 0.01 % Damage
Source Deposited Energy Dose Dose Neutron Fluence
T-493 0.17 kJ 0.70 kGy 0.070 MRad 0.64×1011 n/cm2
TTF-2 (Lars Fröhlich) 0.5 kGy 0.05 MRad
Previous Estimate 1.4 kJ 5.5 kGy 0.55 MRad 1×1011 n/cm2
FLUKA Simulations by J. Vollaire, SLAC
33June 19, 2008 Heinz-Dieter Nuhn, SLAC / LCLSLCLS Magnet Damage Management [email protected]
Additional Evaluation: Field Map Measurements
Grid Size: 26 x 31 Points = 806 Points; Point Spacing: 2 mm; Method: Hall Probe
Reference Magnet SN16673
34June 19, 2008 Heinz-Dieter Nuhn, SLAC / LCLSLCLS Magnet Damage Management [email protected]
Field Map Measurements for M1
Absolute Magnetic Field Amplitudes [T]
Reference Magnet Fields subtracted [T]
35June 19, 2008 Heinz-Dieter Nuhn, SLAC / LCLSLCLS Magnet Damage Management [email protected]
Field Map Measurements for M2
Absolute Magnetic Field Amplitudes [T]
Reference Magnet Fields subtracted [T]
36June 19, 2008 Heinz-Dieter Nuhn, SLAC / LCLSLCLS Magnet Damage Management [email protected]
Field Map Measurements for M3
Absolute Magnetic Field Amplitudes [T]
Reference Magnet Fields subtracted [T]
37June 19, 2008 Heinz-Dieter Nuhn, SLAC / LCLSLCLS Magnet Damage Management [email protected]
Field Map Measurements for M5
Absolute Magnetic Field Amplitudes [T]
Reference Magnet Fields subtracted [T]
38June 19, 2008 Heinz-Dieter Nuhn, SLAC / LCLSLCLS Magnet Damage Management [email protected]
Example of Dose Mapping for the Four Downstream Samples
Courtesy of J. Vollaire, SLAC Courtesy of J. Vollaire, SLAC
Fluence [cm-2] Total Dose [J cm-3]
39June 19, 2008 Heinz-Dieter Nuhn, SLAC / LCLSLCLS Magnet Damage Management [email protected]
Dose Profile versus Magnetization Loss Profile
Courtesy of J. Vollaire, SLAC Courtesy of J. Vollaire, SLAC
40June 19, 2008 Heinz-Dieter Nuhn, SLAC / LCLSLCLS Magnet Damage Management [email protected]
Next Experiments
T-493 was a measurement of the demagnetization of stand-alone magnets with no significant demagnetizing fields present.Inside an undulator, the magnet blocks will be tightly packaged next to one another and magnet blocks might experience the magnetic fields of the neighboring magnets.This scenario will be covered by the “Mini – Undulator Irradiation Test”.Ben Poling, SLAC, has designed and built a Mini-Undulator from spare LCLS Undulator magnet and pole pieces. A second Mini-Undulator (for reference) will be built before the first irradiation run.The magnetization of individual magnet pieces as well as the on-axis magnetic field of the assembled Mini-Undulators will be measured before and after the irradiation processes. Irradiation will be done similar to T-493: A radiation field will be generated by the LCLS electron beam hitting a copper target in ESA.This time, irradiation will be done in phases.
41June 19, 2008 Heinz-Dieter Nuhn, SLAC / LCLSLCLS Magnet Damage Management [email protected]
Courtesy of B. Poling, SLACCourtesy of B. Poling, SLAC
Mini-Undulator Design by Ben Poling
42June 19, 2008 Heinz-Dieter Nuhn, SLAC / LCLSLCLS Magnet Damage Management [email protected]
Mini-Undulator Design by Ben Poling
Courtesy of B. Poling, SLACCourtesy of B. Poling, SLAC
Made from spare LCLS undulator magnet blocks (2 x 2 x 3) and pole pieces (2 x 2 x 5).
Total number of periods: 3.
Gap height and period length identical to LCLS undulator.
Made from spare LCLS undulator magnet blocks (2 x 2 x 3) and pole pieces (2 x 2 x 5).
Total number of periods: 3.
Gap height and period length identical to LCLS undulator.
43June 19, 2008 Heinz-Dieter Nuhn, SLAC / LCLSLCLS Magnet Damage Management [email protected]
Schedule for Test Sequence
Friday, May 16, 2008 20:00- Monday, May 19, 2008 07:00 First irradiation run.
Thursday, June 19, 2008 Irradiation Collaboration Meeting
Friday, June 27, 2008 20:00- Monday, June 30, 2008 07:00 Second irradiation run.
Friday, July 11, 2008 20:00- Monday, July 14, 2008 07:00 Third irradiation run.
Friday, August 1, 2008 20:00- Monday, August 4, 2008 07:00 Fourth irradiation run.
May 2008May 2008Sun Mon Tue Wed Thu Fri Sat
27 28 29 30 1 2 3
4 5 6 7 8 9 10
11 12 13 14 15 16 17
18 19 20 21 22 23 24
25 26 27 28 29 30 31
1 2 3 4 5 6 7
June 2008June 2008Sun Mon Tue Wed Thu Fri Sat
25 26 27 28 29 30 31
1 2 3 4 5 6 7
8 9 10 11 12 13 14
15 16 17 18 19 20 21
22 23 24 25 26 27 28
29 30 1 2 3 4 5
July 2008July 2008Sun Mon Tue Wed Thu Fri Sat
29 30 1 2 3 4 5
6 7 8 9 10 11 12
13 14 15 16 17 18 19
20 21 22 23 24 25 26
27 28 29 30 31 1 2
3 4 5 6 7 8 9
August 2008August 2008Sun Mon Tue Wed Thu Fri Sat
27 28 29 30 31 1 2
3 4 5 6 7 8 9
10 11 12 13 14 15 16
17 18 19 20 21 22 23
24 25 26 27 28 29 30
31 1 2 3 4 5 6
MINI-UND RUN 1 MINI-UND RUN 2 MINI-UND RUN 4MINI-UND RUN 3
CANCELED
44June 19, 2008 Heinz-Dieter Nuhn, SLAC / LCLSLCLS Magnet Damage Management [email protected]
Summary
The plan for monitoring and protecting the LCLS undulators from radiation was presented.Irradiation test at SLAC have been carried out in August 2007:
Nine of the spare Nd2Fe14B permanent magnet pieces for the LCLS undulators have been exposed to radiation fields of various intensities under conditions that can be precisely calculated by FLUKA simulations.The total exposure time was 12.5 days during which a copper target was hit by the 13.7 GeV LCLS electron beam. The total energy of the 36.8x1015 electrons that hit the target was 80 MJ.After a cool-down period, the magnetization levels of the magnets have been measured and compared with the pre-irradiation values. The difference is being compared to the (FLUKA) estimated radiation levels received.In addition, Mini-Undulators (3 periods, each) have been prepared for testing. The magnetic moments of each of the magnets as well as the on-axis magnetic fields after assembly will be measured and recorded. The plan is to irradiate one of them in up to four periods.The present plan to do the irradiation before the August shutdown will probably not work out.
45June 19, 2008 Heinz-Dieter Nuhn, SLAC / LCLSLCLS Magnet Damage Management [email protected]
End of Presentation