superconducting rf accelerators: why all the...
TRANSCRIPT
![Page 1: Superconducting RF Accelerators: Why all the interest?physics.bu.edu/NEPPSR/2007/TALKS-2007/Accelerators_Barletta.pdf · US Particle Accelerator School RF Resistance in Superconductors](https://reader034.vdocument.in/reader034/viewer/2022042805/5f664b621516b9748411eddb/html5/thumbnails/1.jpg)
US Particle Accelerator School
Superconducting RF Accelerators:
Why all the interest?
William A. Barletta
Director, United States Particle Accelerator School
Dept. of Physics, MIT
![Page 2: Superconducting RF Accelerators: Why all the interest?physics.bu.edu/NEPPSR/2007/TALKS-2007/Accelerators_Barletta.pdf · US Particle Accelerator School RF Resistance in Superconductors](https://reader034.vdocument.in/reader034/viewer/2022042805/5f664b621516b9748411eddb/html5/thumbnails/2.jpg)
US Particle Accelerator School
The HEP prespective
ILC
PROJECT X
![Page 3: Superconducting RF Accelerators: Why all the interest?physics.bu.edu/NEPPSR/2007/TALKS-2007/Accelerators_Barletta.pdf · US Particle Accelerator School RF Resistance in Superconductors](https://reader034.vdocument.in/reader034/viewer/2022042805/5f664b621516b9748411eddb/html5/thumbnails/3.jpg)
US Particle Accelerator School
Why do we need RF structures & fields?
![Page 4: Superconducting RF Accelerators: Why all the interest?physics.bu.edu/NEPPSR/2007/TALKS-2007/Accelerators_Barletta.pdf · US Particle Accelerator School RF Resistance in Superconductors](https://reader034.vdocument.in/reader034/viewer/2022042805/5f664b621516b9748411eddb/html5/thumbnails/4.jpg)
US Particle Accelerator School
Possible DC accelerator?
+ V -
B
C
![Page 5: Superconducting RF Accelerators: Why all the interest?physics.bu.edu/NEPPSR/2007/TALKS-2007/Accelerators_Barletta.pdf · US Particle Accelerator School RF Resistance in Superconductors](https://reader034.vdocument.in/reader034/viewer/2022042805/5f664b621516b9748411eddb/html5/thumbnails/5.jpg)
US Particle Accelerator School
Maxwell forbids this!
+ V -
B or in integral form
E =dBdt
EC
ds =tBS
n da
There is no acceleration
without time-varying magnetic flux
C
![Page 6: Superconducting RF Accelerators: Why all the interest?physics.bu.edu/NEPPSR/2007/TALKS-2007/Accelerators_Barletta.pdf · US Particle Accelerator School RF Resistance in Superconductors](https://reader034.vdocument.in/reader034/viewer/2022042805/5f664b621516b9748411eddb/html5/thumbnails/6.jpg)
US Particle Accelerator School
Will this work?
RF-cavity
B
![Page 7: Superconducting RF Accelerators: Why all the interest?physics.bu.edu/NEPPSR/2007/TALKS-2007/Accelerators_Barletta.pdf · US Particle Accelerator School RF Resistance in Superconductors](https://reader034.vdocument.in/reader034/viewer/2022042805/5f664b621516b9748411eddb/html5/thumbnails/7.jpg)
US Particle Accelerator School
We can vary B in an RF cavity
However,
Synchronism condition:
rev = N/frf
RF-cavity
Note that inside the cavity
dB/dt 0
B
![Page 8: Superconducting RF Accelerators: Why all the interest?physics.bu.edu/NEPPSR/2007/TALKS-2007/Accelerators_Barletta.pdf · US Particle Accelerator School RF Resistance in Superconductors](https://reader034.vdocument.in/reader034/viewer/2022042805/5f664b621516b9748411eddb/html5/thumbnails/8.jpg)
US Particle Accelerator School
We can arrange rf-cavities in many ways
Microtron Synchrotron
Linac
![Page 9: Superconducting RF Accelerators: Why all the interest?physics.bu.edu/NEPPSR/2007/TALKS-2007/Accelerators_Barletta.pdf · US Particle Accelerator School RF Resistance in Superconductors](https://reader034.vdocument.in/reader034/viewer/2022042805/5f664b621516b9748411eddb/html5/thumbnails/9.jpg)
US Particle Accelerator School
RF cavities: Basic concepts
Fields and voltages are complex quantities
˜ V = Vei t + o
Zo is the reference plane
At t = 0 particle receives
maximum voltage gain
![Page 10: Superconducting RF Accelerators: Why all the interest?physics.bu.edu/NEPPSR/2007/TALKS-2007/Accelerators_Barletta.pdf · US Particle Accelerator School RF Resistance in Superconductors](https://reader034.vdocument.in/reader034/viewer/2022042805/5f664b621516b9748411eddb/html5/thumbnails/10.jpg)
US Particle Accelerator School
Basic principles:Reciprocity & superposition
If you can kick the beam, the beam can kick you
==>
Total cavity voltage = Vgenerator+ Vbeam-induced
Fields in cavity = Egenerator+ Ebeam-induced
![Page 11: Superconducting RF Accelerators: Why all the interest?physics.bu.edu/NEPPSR/2007/TALKS-2007/Accelerators_Barletta.pdf · US Particle Accelerator School RF Resistance in Superconductors](https://reader034.vdocument.in/reader034/viewer/2022042805/5f664b621516b9748411eddb/html5/thumbnails/11.jpg)
US Particle Accelerator School
Basic principles: Energy conservation
Total energy in the particles and the cavity is conserved
Beam loading
Ui Uf
Wc
Wc = Ui - Uf
![Page 12: Superconducting RF Accelerators: Why all the interest?physics.bu.edu/NEPPSR/2007/TALKS-2007/Accelerators_Barletta.pdf · US Particle Accelerator School RF Resistance in Superconductors](https://reader034.vdocument.in/reader034/viewer/2022042805/5f664b621516b9748411eddb/html5/thumbnails/12.jpg)
US Particle Accelerator School
Basic components of an RF cavity
Outer region: Large, single turn Inductor
Central region: Large plate Capacitor
Beam (Load) current
I
B
EDisplacement current
Wall current
a
RdPower feed from rf - generator
![Page 13: Superconducting RF Accelerators: Why all the interest?physics.bu.edu/NEPPSR/2007/TALKS-2007/Accelerators_Barletta.pdf · US Particle Accelerator School RF Resistance in Superconductors](https://reader034.vdocument.in/reader034/viewer/2022042805/5f664b621516b9748411eddb/html5/thumbnails/13.jpg)
US Particle Accelerator School
Lumped circuit analogy of resonant cavity
V(t)
I(t)
C
L
R Z( ) = j C + ( j L + R) 1[ ]1
Z( ) ~ 1+2
o2
+ ( RC)2
1
The resonant frequency is o = 1LC
Width to reduce
Z by e2
0
=R
LC=1
Q
![Page 14: Superconducting RF Accelerators: Why all the interest?physics.bu.edu/NEPPSR/2007/TALKS-2007/Accelerators_Barletta.pdf · US Particle Accelerator School RF Resistance in Superconductors](https://reader034.vdocument.in/reader034/viewer/2022042805/5f664b621516b9748411eddb/html5/thumbnails/14.jpg)
US Particle Accelerator School
Figure of Merit: Accelerating voltage
The voltage varies during the time that bunch takes to cross the gap
reduction of the peak voltage by
d
=sin 2( )
2 where = d
c
Vt
2
TrfFor maximum acceleration ==> = 2/
Epk
![Page 15: Superconducting RF Accelerators: Why all the interest?physics.bu.edu/NEPPSR/2007/TALKS-2007/Accelerators_Barletta.pdf · US Particle Accelerator School RF Resistance in Superconductors](https://reader034.vdocument.in/reader034/viewer/2022042805/5f664b621516b9748411eddb/html5/thumbnails/15.jpg)
US Particle Accelerator School
Figure of merit from circuits - Q
E =μo2
Hv
2dv =
1
2L IoIo
*
P = Rsurf
2H
s
2ds =
1
2IoIo
*Rsurf
Q = LC
Rsurf
= o
1
Q = o o Energy stored
Time average power loss=
2 o Energy stored
Energy lost per cycle
Rsurf =1
Conductivity o Skin depth~ 1/ 2
![Page 16: Superconducting RF Accelerators: Why all the interest?physics.bu.edu/NEPPSR/2007/TALKS-2007/Accelerators_Barletta.pdf · US Particle Accelerator School RF Resistance in Superconductors](https://reader034.vdocument.in/reader034/viewer/2022042805/5f664b621516b9748411eddb/html5/thumbnails/16.jpg)
US Particle Accelerator School
What makes SC RF attractive?
![Page 17: Superconducting RF Accelerators: Why all the interest?physics.bu.edu/NEPPSR/2007/TALKS-2007/Accelerators_Barletta.pdf · US Particle Accelerator School RF Resistance in Superconductors](https://reader034.vdocument.in/reader034/viewer/2022042805/5f664b621516b9748411eddb/html5/thumbnails/17.jpg)
US Particle Accelerator School
Recall the circuit analog
V(t)
I(t)
C
L
Rsurf
As Rsurf ==> 0, the Q ==>
In practice,
Qnc ~ 104 Qsc ~ 1011
![Page 18: Superconducting RF Accelerators: Why all the interest?physics.bu.edu/NEPPSR/2007/TALKS-2007/Accelerators_Barletta.pdf · US Particle Accelerator School RF Resistance in Superconductors](https://reader034.vdocument.in/reader034/viewer/2022042805/5f664b621516b9748411eddb/html5/thumbnails/18.jpg)
US Particle Accelerator School
Figure of merit for accelerating cavity:power to produce the accelerating field
Resistive input (shunt) impedance at relates power dissipated in walls to
accelerating voltage
Linac literature more commonly defines “shunt impedance” without the “2”
For SC-rf P is reduced by orders of magnitude
BUT, it is deposited @ 2K
Rin = V 2(t)
P =
Vo2
2P = Q L
C
Rin = Vo
2
P ~
1
Rsurf
![Page 19: Superconducting RF Accelerators: Why all the interest?physics.bu.edu/NEPPSR/2007/TALKS-2007/Accelerators_Barletta.pdf · US Particle Accelerator School RF Resistance in Superconductors](https://reader034.vdocument.in/reader034/viewer/2022042805/5f664b621516b9748411eddb/html5/thumbnails/19.jpg)
US Particle Accelerator School
Translate circuit model back to directly
driven, re-entrant RF cavity model
Outer region: Large, single turn Inductor
Central region: Large plate Capacitor
Beam (Load) current
Displacement current
I
B
E
Wall current
a
Rd
L =μo a
2
2 (R + a)
C = o
R2
d
o = 1LC
= c2((R + a)d
R2a2
12
Q – set by resistance in outer region
Q =LC
R surface= L
R surface
Expanding outer region
raises Q
Narrowing gap
raises shunt impedance
![Page 20: Superconducting RF Accelerators: Why all the interest?physics.bu.edu/NEPPSR/2007/TALKS-2007/Accelerators_Barletta.pdf · US Particle Accelerator School RF Resistance in Superconductors](https://reader034.vdocument.in/reader034/viewer/2022042805/5f664b621516b9748411eddb/html5/thumbnails/20.jpg)
US Particle Accelerator School
In an ideal pillbox, is independent of L
L
Ez
R
B
Ez
B
Rela
tive inte
nsity
r/R
T010
CL
= 2.405c
REz (r) = Eo Jo c
r
==>==>
![Page 21: Superconducting RF Accelerators: Why all the interest?physics.bu.edu/NEPPSR/2007/TALKS-2007/Accelerators_Barletta.pdf · US Particle Accelerator School RF Resistance in Superconductors](https://reader034.vdocument.in/reader034/viewer/2022042805/5f664b621516b9748411eddb/html5/thumbnails/21.jpg)
US Particle Accelerator School
Simple consequences of pillbox model
L
Ez
R
B
Increasing R lowers frequency
==> Stored Energy, E ~ -2
E ~ Ez2
Beam loading lowers Ez for the
next bunch
Lowering lowers the fractional
beam loading
Raising lowers Q ~ -1/2
If time between beam pulses,
Ts ~ Q/
almost all E is lost in the walls
![Page 22: Superconducting RF Accelerators: Why all the interest?physics.bu.edu/NEPPSR/2007/TALKS-2007/Accelerators_Barletta.pdf · US Particle Accelerator School RF Resistance in Superconductors](https://reader034.vdocument.in/reader034/viewer/2022042805/5f664b621516b9748411eddb/html5/thumbnails/22.jpg)
US Particle Accelerator School
The beam tube makes the field modes(& cell design) more complicated
Ez
B
Peak E no longer on axis
Epk ~ 2 - 3 x Eacc
FOM = Epk/Eacc
o sensitive to cavity length
Mechanical tuning & detuning
Beam tubes add length & $’s
w/o acceleration
Beam induced voltages ~ a-3
Instabilities
a
![Page 23: Superconducting RF Accelerators: Why all the interest?physics.bu.edu/NEPPSR/2007/TALKS-2007/Accelerators_Barletta.pdf · US Particle Accelerator School RF Resistance in Superconductors](https://reader034.vdocument.in/reader034/viewer/2022042805/5f664b621516b9748411eddb/html5/thumbnails/23.jpg)
US Particle Accelerator School
Comparison of SC and NC RF
Superconducting RF
High gradient
==> 1 GHz, meticulous care
Mid-frequencies
==> Large stored energy, Es
Large Es
==> very small E/E
Large Q
==> high efficiency
Normal Conductivity RF
High gradient
==> high frequency (5 - 17 GHz)
High frequency
==> low stored energy
Low Es
==> ~10x larger E/E
Low Q
==> reduced efficiency
![Page 24: Superconducting RF Accelerators: Why all the interest?physics.bu.edu/NEPPSR/2007/TALKS-2007/Accelerators_Barletta.pdf · US Particle Accelerator School RF Resistance in Superconductors](https://reader034.vdocument.in/reader034/viewer/2022042805/5f664b621516b9748411eddb/html5/thumbnails/24.jpg)
US Particle Accelerator School
Rf-power in
In warm linacs “nose cones” optimize the voltage
per cell with respect to resistive dissipation
Linacs can be considered as a series of
distorted pillbox cavities…
Q =LC
R surface
a
![Page 25: Superconducting RF Accelerators: Why all the interest?physics.bu.edu/NEPPSR/2007/TALKS-2007/Accelerators_Barletta.pdf · US Particle Accelerator School RF Resistance in Superconductors](https://reader034.vdocument.in/reader034/viewer/2022042805/5f664b621516b9748411eddb/html5/thumbnails/25.jpg)
US Particle Accelerator School
Linacs cells are linked to minimize cost
==> coupled oscillators ==>multiple modes
Zero mode mode
![Page 26: Superconducting RF Accelerators: Why all the interest?physics.bu.edu/NEPPSR/2007/TALKS-2007/Accelerators_Barletta.pdf · US Particle Accelerator School RF Resistance in Superconductors](https://reader034.vdocument.in/reader034/viewer/2022042805/5f664b621516b9748411eddb/html5/thumbnails/26.jpg)
US Particle Accelerator School
Modes of a two-cell cavity
![Page 27: Superconducting RF Accelerators: Why all the interest?physics.bu.edu/NEPPSR/2007/TALKS-2007/Accelerators_Barletta.pdf · US Particle Accelerator School RF Resistance in Superconductors](https://reader034.vdocument.in/reader034/viewer/2022042805/5f664b621516b9748411eddb/html5/thumbnails/27.jpg)
US Particle Accelerator School
9-cavity TESLA cell
![Page 28: Superconducting RF Accelerators: Why all the interest?physics.bu.edu/NEPPSR/2007/TALKS-2007/Accelerators_Barletta.pdf · US Particle Accelerator School RF Resistance in Superconductors](https://reader034.vdocument.in/reader034/viewer/2022042805/5f664b621516b9748411eddb/html5/thumbnails/28.jpg)
US Particle Accelerator School
Enter Superconductivity
1911
![Page 29: Superconducting RF Accelerators: Why all the interest?physics.bu.edu/NEPPSR/2007/TALKS-2007/Accelerators_Barletta.pdf · US Particle Accelerator School RF Resistance in Superconductors](https://reader034.vdocument.in/reader034/viewer/2022042805/5f664b621516b9748411eddb/html5/thumbnails/29.jpg)
US Particle Accelerator School
Electrons in Solids - naïve picture
![Page 30: Superconducting RF Accelerators: Why all the interest?physics.bu.edu/NEPPSR/2007/TALKS-2007/Accelerators_Barletta.pdf · US Particle Accelerator School RF Resistance in Superconductors](https://reader034.vdocument.in/reader034/viewer/2022042805/5f664b621516b9748411eddb/html5/thumbnails/30.jpg)
US Particle Accelerator School
Energy distribution of electrons in
normal conductors
EFermi level
T = 0 T > 0
![Page 31: Superconducting RF Accelerators: Why all the interest?physics.bu.edu/NEPPSR/2007/TALKS-2007/Accelerators_Barletta.pdf · US Particle Accelerator School RF Resistance in Superconductors](https://reader034.vdocument.in/reader034/viewer/2022042805/5f664b621516b9748411eddb/html5/thumbnails/31.jpg)
US Particle Accelerator School
Electron-Phonon interaction ==>electron pairs - BCS theory
An e- moving thru a conductor attracts
nearby ions. The lattice deformation
causes another e-, with opposite "spin",
to move into region of higher + charge
density.
The two e- are held together with a
binding energy, 2
![Page 32: Superconducting RF Accelerators: Why all the interest?physics.bu.edu/NEPPSR/2007/TALKS-2007/Accelerators_Barletta.pdf · US Particle Accelerator School RF Resistance in Superconductors](https://reader034.vdocument.in/reader034/viewer/2022042805/5f664b621516b9748411eddb/html5/thumbnails/32.jpg)
US Particle Accelerator School
In superconductors interaction of electrons
with lattice phonons ==> pairs (bosons)
Possibility of Bose condensate at Tcritical
T = 0
E Energy gap -
Two fluid model:
For Tc >T > 0, excitation of unpaired
electrons
where 2 is the energy to break apart the
Cooper pairs, until no electrons are paired
above Tc
![Page 33: Superconducting RF Accelerators: Why all the interest?physics.bu.edu/NEPPSR/2007/TALKS-2007/Accelerators_Barletta.pdf · US Particle Accelerator School RF Resistance in Superconductors](https://reader034.vdocument.in/reader034/viewer/2022042805/5f664b621516b9748411eddb/html5/thumbnails/33.jpg)
US Particle Accelerator School
DC conductivity in superconductors
DC resistance = 0
because unpaired electrons
are shorted out by Cooper
pairs.
dc
![Page 34: Superconducting RF Accelerators: Why all the interest?physics.bu.edu/NEPPSR/2007/TALKS-2007/Accelerators_Barletta.pdf · US Particle Accelerator School RF Resistance in Superconductors](https://reader034.vdocument.in/reader034/viewer/2022042805/5f664b621516b9748411eddb/html5/thumbnails/34.jpg)
US Particle Accelerator School
RF Resistance in Superconductors
RF resistance is finite because
Cooper pairs have inertia
unpaied electrons “see” an
electric field.
More resistance the more the
sc pairs are jiggled around
1.5 GHz
Residual resistance
Exponential drop
Compare with Cu: Rs ~ 10 m
More resistance the more
unpaired electrons are excited
![Page 35: Superconducting RF Accelerators: Why all the interest?physics.bu.edu/NEPPSR/2007/TALKS-2007/Accelerators_Barletta.pdf · US Particle Accelerator School RF Resistance in Superconductors](https://reader034.vdocument.in/reader034/viewer/2022042805/5f664b621516b9748411eddb/html5/thumbnails/35.jpg)
US Particle Accelerator School
In practice several effects limit the mostimportant measure of cell performance
11
10
9
8
0 25 50 MV/m
Accelerating Field
Residual losses
Multipacting
Field emission
Thermal breakdown
Quench
Ideal
10
10
10
10
Q
Grain boundaries
Oxide interface
![Page 36: Superconducting RF Accelerators: Why all the interest?physics.bu.edu/NEPPSR/2007/TALKS-2007/Accelerators_Barletta.pdf · US Particle Accelerator School RF Resistance in Superconductors](https://reader034.vdocument.in/reader034/viewer/2022042805/5f664b621516b9748411eddb/html5/thumbnails/36.jpg)
US Particle Accelerator School
Multipacting Solution
First spherical, later elliptical
shape cells.
Electrons drift to equator
Electric field at equator is 0
MP electrons don’t gain energy
MP stops350-MHz LEP-II cavity (CERN)
![Page 37: Superconducting RF Accelerators: Why all the interest?physics.bu.edu/NEPPSR/2007/TALKS-2007/Accelerators_Barletta.pdf · US Particle Accelerator School RF Resistance in Superconductors](https://reader034.vdocument.in/reader034/viewer/2022042805/5f664b621516b9748411eddb/html5/thumbnails/37.jpg)
US Particle Accelerator School
Thermometry at a quench point
![Page 38: Superconducting RF Accelerators: Why all the interest?physics.bu.edu/NEPPSR/2007/TALKS-2007/Accelerators_Barletta.pdf · US Particle Accelerator School RF Resistance in Superconductors](https://reader034.vdocument.in/reader034/viewer/2022042805/5f664b621516b9748411eddb/html5/thumbnails/38.jpg)
US Particle Accelerator School
Why do we need beams?
Collide beams
FOMs: Collision rate, energy
stability, Accelerating field
Examples: LHC, ILC, RHIC
![Page 39: Superconducting RF Accelerators: Why all the interest?physics.bu.edu/NEPPSR/2007/TALKS-2007/Accelerators_Barletta.pdf · US Particle Accelerator School RF Resistance in Superconductors](https://reader034.vdocument.in/reader034/viewer/2022042805/5f664b621516b9748411eddb/html5/thumbnails/39.jpg)
US Particle Accelerator School
In LHC storage rings…
Limited space & Large rf trapping of particles
V/cavity must be high
Bunch length must be large ( 1 event/cm in luminous region)
RF frequency must be low
Energy lost in walls must be small
Rsurf must be small
SC cavities were the only practical choiceSC cavities were the only practical choice
![Page 40: Superconducting RF Accelerators: Why all the interest?physics.bu.edu/NEPPSR/2007/TALKS-2007/Accelerators_Barletta.pdf · US Particle Accelerator School RF Resistance in Superconductors](https://reader034.vdocument.in/reader034/viewer/2022042805/5f664b621516b9748411eddb/html5/thumbnails/40.jpg)
US Particle Accelerator School
For ILC SC rf provides high power, highquality beams at high efficiency
~4.5 km ~13 km~13 km
• To deliver required luminosity (500 fb-1 in 4 years) ==>
– powerful polarized electron & positron beams (11 MW /beam)
– tiny beams at collision point ==> minimizing beam-structure interaction
• To limit power consumption ==> high “wall plug” to beam power efficiency
– Even with SC rf, the site power is still 230 MW !
![Page 41: Superconducting RF Accelerators: Why all the interest?physics.bu.edu/NEPPSR/2007/TALKS-2007/Accelerators_Barletta.pdf · US Particle Accelerator School RF Resistance in Superconductors](https://reader034.vdocument.in/reader034/viewer/2022042805/5f664b621516b9748411eddb/html5/thumbnails/41.jpg)
US Particle Accelerator School
Why do we need beams?
Intense secondary beams
FOM: Secondaries/primary
Examples: spallation neutrons,
neutrino beams
1 MW target at SNS1 MW target at SNS
![Page 42: Superconducting RF Accelerators: Why all the interest?physics.bu.edu/NEPPSR/2007/TALKS-2007/Accelerators_Barletta.pdf · US Particle Accelerator School RF Resistance in Superconductors](https://reader034.vdocument.in/reader034/viewer/2022042805/5f664b621516b9748411eddb/html5/thumbnails/42.jpg)
US Particle Accelerator School
The Spallation Neutron Source
1 MW @ 1GeV (compare with ILC 11 MW at 500 GeV
(upgradeable to 4 MW)
==> miniscule beam loss into accelerator
==> large aperture in cavities ==> large cavities
==> low frequency
==> high energy stability
==>large stored energy
==> high efficiency at Ez
==> SC RF SNS
![Page 43: Superconducting RF Accelerators: Why all the interest?physics.bu.edu/NEPPSR/2007/TALKS-2007/Accelerators_Barletta.pdf · US Particle Accelerator School RF Resistance in Superconductors](https://reader034.vdocument.in/reader034/viewer/2022042805/5f664b621516b9748411eddb/html5/thumbnails/43.jpg)
US Particle Accelerator School
Proton Intensity Frontier Option:Project X
ILC-style 8 GeV H- Linac
9mA x 1 msec x 5 Hz
200 kW
at 8 GeV
Stripping Foil
Recycler3 linac pulses / fill
Main Injector1.4 sec cycle
>2 MW
at 120 GeV
Initially NOvA
Possibly DUSEL later
![Page 44: Superconducting RF Accelerators: Why all the interest?physics.bu.edu/NEPPSR/2007/TALKS-2007/Accelerators_Barletta.pdf · US Particle Accelerator School RF Resistance in Superconductors](https://reader034.vdocument.in/reader034/viewer/2022042805/5f664b621516b9748411eddb/html5/thumbnails/44.jpg)
US Particle Accelerator School
Matter to energy:Synchrotron radiation science
Synchrotron light source
(pulsed incoherent X-ray emission)
FOM: Brilliance v.
B = ph/s/mm2/mrad2/0.1%BW
Pulse duration
Science with X-rays Imaging
Spectroscopy
ERLsERLs
FELs
3rd Generation Sources
![Page 45: Superconducting RF Accelerators: Why all the interest?physics.bu.edu/NEPPSR/2007/TALKS-2007/Accelerators_Barletta.pdf · US Particle Accelerator School RF Resistance in Superconductors](https://reader034.vdocument.in/reader034/viewer/2022042805/5f664b621516b9748411eddb/html5/thumbnails/45.jpg)
US Particle Accelerator School
Matter to energy: Energy Recovery Linacs Hard X-rays ==> ~5 Hard X-rays ==> ~5 GeVGeV
Synchrotron light source
(pulsed incoherent X-ray emission)
Pulse rates Pulse rates –– kHz => MHz kHz => MHz
X-ray pulse durationX-ray pulse duration 1 1 psps
High average High average e-beam e-beam brilliancebrilliance
&& e-beam e-beam duration duration 1 1 psps
One pass throughOne pass through ringring
Recover beam energyRecover beam energy
High efficiencyHigh efficiency
SC RFSC RF
![Page 46: Superconducting RF Accelerators: Why all the interest?physics.bu.edu/NEPPSR/2007/TALKS-2007/Accelerators_Barletta.pdf · US Particle Accelerator School RF Resistance in Superconductors](https://reader034.vdocument.in/reader034/viewer/2022042805/5f664b621516b9748411eddb/html5/thumbnails/46.jpg)
US Particle Accelerator School
Even higher brightness requires
coherent emission ==> FEL
Free electron laser
FOM: Brightness v.
Time structure
![Page 47: Superconducting RF Accelerators: Why all the interest?physics.bu.edu/NEPPSR/2007/TALKS-2007/Accelerators_Barletta.pdf · US Particle Accelerator School RF Resistance in Superconductors](https://reader034.vdocument.in/reader034/viewer/2022042805/5f664b621516b9748411eddb/html5/thumbnails/47.jpg)
US Particle Accelerator School
Full range of FEL-based science requires…
Pulses rates 10 Hz to 10 MHz (NC limited to ~ 100 Hz)
High efficiency
Pulse duration 10 fs - 1 ps
High gain
Excellent beam emittance
==> Minimize wakefield effect
==> large aperture
==> low frequency
Stable beam energy & intensity
==> large stored energy in cavities
==> high Q
===> SC RF
![Page 48: Superconducting RF Accelerators: Why all the interest?physics.bu.edu/NEPPSR/2007/TALKS-2007/Accelerators_Barletta.pdf · US Particle Accelerator School RF Resistance in Superconductors](https://reader034.vdocument.in/reader034/viewer/2022042805/5f664b621516b9748411eddb/html5/thumbnails/48.jpg)
US Particle Accelerator School
8 GeV Superconducting LinacWith X-Ray FEL, 8 GeV & Spallation Sources, ILC & -factory
Hegemony in accelerator-based physics
![Page 49: Superconducting RF Accelerators: Why all the interest?physics.bu.edu/NEPPSR/2007/TALKS-2007/Accelerators_Barletta.pdf · US Particle Accelerator School RF Resistance in Superconductors](https://reader034.vdocument.in/reader034/viewer/2022042805/5f664b621516b9748411eddb/html5/thumbnails/49.jpg)
US Particle Accelerator School