1/18 the distribution of synchrotron radiation power in the ir c. h. yu ir overview sr distribution...
TRANSCRIPT
11/18/18
The Distribution of The Distribution of Synchrotron Radiation Synchrotron Radiation
Power in the IRPower in the IR
C. H. YuC. H. Yu
• IR Overview
• SR Distribution in the IR
• The Protection of SR Power
22/18/18
IR OverviewIR Overview
Top view of IR vacuum chamberTop view of IR vacuum chamber
The central part is Be pipe with the length of The central part is Be pipe with the length of 0.3m and inner diameter of 63mm. 0.3m and inner diameter of 63mm.
The Be pipe is welded to a copper cylinder with The Be pipe is welded to a copper cylinder with the length of 0.55m and inner diameter of 63mm. the length of 0.55m and inner diameter of 63mm.
33/18/18
SR Distribution in the IR1. Formula for the SR Calculation
Synchrotron radiation is produced when an Synchrotron radiation is produced when an electron (or positron) trajectory curves in the electron (or positron) trajectory curves in the magnetic field of a dipole or quadrupole. magnetic field of a dipole or quadrupole. Photons are emitted in a direction tangential Photons are emitted in a direction tangential to the particle instantaneous trajectory with to the particle instantaneous trajectory with differential power: differential power:
]m[/]A[I]GeV[E.[kW] beam
447882
ddP
Where is the local radius of curvature and d is the deflection angle.
44/18/18
Since the BEPCII will be operated with Since the BEPCII will be operated with colliding mode and SR mode, which have colliding mode and SR mode, which have different synchrotron radiation sources different synchrotron radiation sources and synchrotron radiation fan and synchrotron radiation fan distributions, the situation of SR must be distributions, the situation of SR must be studied separately.studied separately.
55/18/18
SR Distribution in the IR2. Colliding Mode
The colliding mode will be operated at energy The colliding mode will be operated at energy range 1.0GeV to 2.1GeV. However the case range 1.0GeV to 2.1GeV. However the case with maximum SR power distribution is with maximum SR power distribution is 1.89GeV as well as beam current of 0.91A.1.89GeV as well as beam current of 0.91A.
For the e- beam, synchrotron radiation fans in For the e- beam, synchrotron radiation fans in the IR are mainly generated from the final the IR are mainly generated from the final bending magnet R4OWB and from the IR bending magnet R4OWB and from the IR quadrupoles due to the crossing angle quadrupoles due to the crossing angle trajectory. trajectory. The synchrotron radiation generated by e+ The synchrotron radiation generated by e+ beam is symmetrical with e- beambeam is symmetrical with e- beam..
66/18/18
SR Distribution in the IR2. Colliding Mode (Continued)
The SR fans in the IR produced by e- beam.The SR fans in the IR produced by e- beam.
The shading density indicates the relative power of each fan. The darker shading means higher power density.
77/18/18
SR Distribution in the IR2. Colliding Mode (Continued)
As the e- beam travels through the final bending mAs the e- beam travels through the final bending magnet R4OWB (13.4m from the IP) and enters the IR,agnet R4OWB (13.4m from the IP) and enters the IR, it generates SR fan with the total power it generates SR fan with the total power 396W396W ( (EEcc==0.7keV0.7keV). The SR fan of center beam passes through ). The SR fan of center beam passes through the IP and spreads horizontally up to 0.5m from ththe IP and spreads horizontally up to 0.5m from the IP. It contributes about e IP. It contributes about 3.0W3.0W of SR power on the of SR power on the 0.5m~0.7m beam pipe from the IP. 0.5m~0.7m beam pipe from the IP.
88/18/18
SR Distribution in the IR2. Colliding Mode (Continued)
There are 6 quadrupoles between R4OWB and the There are 6 quadrupoles between R4OWB and the IP. Among them R4SCQ magnet is the largest radiaIP. Among them R4SCQ magnet is the largest radiation source due to its off-axis installation. The total tion source due to its off-axis installation. The total SR power generated by the R4SCQ magnet is SR power generated by the R4SCQ magnet is 95.295.2WW ( (EEcc<0.7keV<0.7keV). The SR fan of center beam also can r). The SR fan of center beam also can reach 0.5m from the IP. About each 0.5m from the IP. About 19.2W19.2W of SR power fr of SR power from R4SCQ can strike on the 0.5m~0.7m beam pipe om R4SCQ can strike on the 0.5m~0.7m beam pipe from the IP. The rest of SR fans travels out of the nfrom the IP. The rest of SR fans travels out of the near IR and is absorbed on the surface at 3m~4m froear IR and is absorbed on the surface at 3m~4m from the IP. m the IP.
99/18/18
SR Distribution in the IR2. Colliding Mode (Continued)
Most of the synchrotron radiation power (521.3W) gMost of the synchrotron radiation power (521.3W) generated by R3SCQ and ISPBenerated by R3SCQ and ISPB((EEcc=1.0keV=1.0keV).). magnets hi magnets hits the beam pipe at 3.0m~4.4m from the IP.ts the beam pipe at 3.0m~4.4m from the IP.
In the proposed design, the photons with In the proposed design, the photons with about 0.5W of SR power contributed by both about 0.5W of SR power contributed by both e+ & e-beams within 10e+ & e-beams within 10xx of beam size will hit of beam size will hit directly on the detector beryllium pipe. directly on the detector beryllium pipe.
1010/18/18
SR Distribution in the IR2. Colliding Mode (Continued)
During the operation if there is extreme case During the operation if there is extreme case such as 5mm orbit and 2mrad angle distortion. such as 5mm orbit and 2mrad angle distortion. The SR power on beam pipe beside Be pipe is The SR power on beam pipe beside Be pipe is 61W and Be pipe is 10.1W. 61W and Be pipe is 10.1W.
The SR distribution caused by the final bending The SR distribution caused by the final bending magnet R4OWB and R3OWB are sensitive to magnet R4OWB and R3OWB are sensitive to the beam orbit distortion. They are the only SR the beam orbit distortion. They are the only SR source which is sensitive to orbit distortion.source which is sensitive to orbit distortion.
1111/18/18
SR Distribution in the IR3. SR Mode
The SR mode will be operated at energy of 2.5GeV. The SR mode will be operated at energy of 2.5GeV. The maximum beam current is 250mA.The maximum beam current is 250mA.
The SR power in the IR mainly generated by The SR power in the IR mainly generated by the final bending magnet R4OWB and the the final bending magnet R4OWB and the superconducting bending magnet superconducting bending magnet R4SCB/R3SCB nearby the IP. R4SCB/R3SCB nearby the IP.
For the SR mode, only e- beam is employed. For the SR mode, only e- beam is employed.
1212/18/18
SR Distribution in the IR3. SR Mode (Continued)
The SR fans in the IR produced by e- beam.The SR fans in the IR produced by e- beam.
The shading density indicates the relative power of each fan. The darker shading means higher power density.
1313/18/18
SR Distribution in the IR3. SR Mode (Continued)
As the e- beam travels through the final bending mAs the e- beam travels through the final bending magnet R4OWB and enters the IR, it generates SR faagnet R4OWB and enters the IR, it generates SR fan with the total power n with the total power 333W333W ( (EEcc=1.7keV=1.7keV). The SR fa). The SR fan of center beam passes through the IP and spreadn of center beam passes through the IP and spreads horizontally up to 0.5m from the IP. It contributes horizontally up to 0.5m from the IP. It contributes about s about 2.5W2.5W of SR power on the 0.5m~0.7m beam of SR power on the 0.5m~0.7m beam pipe from the IP. pipe from the IP.
1414/18/18
SR Distribution in the IR3. SR Mode (Continued)
The total power of the SR fan generated by R4SCB The total power of the SR fan generated by R4SCB is is 223W223W ( (EEcc=2.3keV=2.3keV). The SR fan of center beam als). The SR fan of center beam also can reach 0.5m from the IP. About o can reach 0.5m from the IP. About 25.3W25.3W of SR p of SR power from R4SCB can strike on the 0.5m~0.7m beaower from R4SCB can strike on the 0.5m~0.7m beam pipe from the IP. The rest of SR fan from R4SCB tm pipe from the IP. The rest of SR fan from R4SCB travels out of the near IR and is absorbed on two suravels out of the near IR and is absorbed on two surfaces, one is a mask placed in front of the ISPB serfaces, one is a mask placed in front of the ISPB septum, the other is the beam pipe at 3m~4m from tptum, the other is the beam pipe at 3m~4m from the IP. he IP.
1515/18/18
SR Distribution in the IR3. SR Mode (Continued)
About half of the SR power 223W generated About half of the SR power 223W generated from R3SCB hits the mask placed in front of the from R3SCB hits the mask placed in front of the ISPB septum. The remainder mainly strikes the ISPB septum. The remainder mainly strikes the beam pipe between the R3Q1a and R3Q1b. beam pipe between the R3Q1a and R3Q1b.
In the proposed design, the photons with about In the proposed design, the photons with about 0.2W of SR power within 100.2W of SR power within 10xx of beam size will of beam size will hit directly on the detector beryllium pipe. hit directly on the detector beryllium pipe.
1616/18/18
SR Distribution in the IR3. SR Mode (Continued)
During the operation if there is extreme case During the operation if there is extreme case such as 5mm orbit and 2mrad angle distortion. such as 5mm orbit and 2mrad angle distortion. The SR power on beam pipe beside Be pipe is The SR power on beam pipe beside Be pipe is 59W and Be pipe is 4.3W. 59W and Be pipe is 4.3W.
Final bending magnet is the only SR source Final bending magnet is the only SR source which is sensitive to orbit distortion.which is sensitive to orbit distortion.
1717/18/18
The Protection of SR Power
We have designed the water cooling structure in We have designed the water cooling structure in the beam pipe 0.5~0.7mthe beam pipe 0.5~0.7m from the IP, from the IP, the crotch the crotch beam pipe beam pipe and and the beam pipe 3.0~4.0mthe beam pipe 3.0~4.0m from the from the IP to avoid the heat problem in these region .IP to avoid the heat problem in these region .
Except Be pipe, the material of vacuum Except Be pipe, the material of vacuum chamber within chamber within 3.5m is chosen as 3.5m is chosen as coppercopper for for its low coefficient of photon-induced gas its low coefficient of photon-induced gas desorption, high thermal conductivity and desorption, high thermal conductivity and large photon absorption coefficient.large photon absorption coefficient.
1818/18/18
Summary
The SR power distribution of colliding The SR power distribution of colliding mode and SR mode have been estimated. mode and SR mode have been estimated. The water cooling structure has been The water cooling structure has been designed in the region with heat problem.designed in the region with heat problem.
It’s difficult to stop both direct and once-It’s difficult to stop both direct and once-scattering photons emitted within 10scattering photons emitted within 10xx of beam of beam size at all magnets hitting on the Be pipe. size at all magnets hitting on the Be pipe.