Download A new italian test facility for accelerator magnets

SIF, 22/09/2015
A new italian test facility for accelerator
magnets
Umberto Gambardella
G. Iannone, A. Saggese, A. Ferrentino, N. Califano
INFN Sezione di Napoli,
Gruppo Collegato di Salerno
CNR-INFM
SUPERMAT
Regional Laboratory INFM
SIF, 22/09/2015
Overview
• INFN motivation for new infrastructure
• Joining different needs to make a strong
proposal
• The infrastructure potentials
• INFN targets and equipment
• Conclusion
SIF, 22/09/2015
INFN motivations
In the recent past the the DISCORAP project
(a prototype dipole for the FAIR SIS300
machine) made it clear there was not a
laboratory where to perform a full test of such
advanced magnet, so we just performed
limited tests at our LASA laboratory.
DISCORAP prototype:
4.5 T bended dipole
4 m long, 6 tons weight
ramp rate 1 T/s
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• We did not have available any cryogenic
plant providing supercritical He.
• We did not have available a suitable Power
Converter to run the magnet at 1 T/s.
Actually the study of losses in power
superconductivity is of primary interest. The easiest
way to procure these (expensive) equipment is to
use special funds available for underdeveloped
areas. The drawback is that the infrastructure must
be installed in the underdeveloped regions.
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A wider approach
To strengthen the proposal we take the
opportunity that also ENEA was looking for
support to its high current CICC cable test
facility. Finally, due to long and withstanding
cooperation with University of Salerno, it
became a natural host institution where to
realize a new infrastructure for power
superconductivity (NAFASSY). A joint
proposal was submitted on Aug. 2011, and
funded with 10.8 M€ in Dec. 2011.
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PON a3_0007 rafforzamento strutturale
Realizzazione di una facility di test per magneti superconduttori e misure di corrente critica
Università di Salerno, € 2.375.634,34 (+ 700 k€ per la formazione)
ENEA, € 2.541.903,50
INFN, Sezione di Napoli, € 3.472.586,20
CRdC scarl, Napoli, € 1.709.875,96
CNR-INFM
SUPERMAT
Regional Laboratory INFM
SIF, 22/09/2015
The infrastructure potentials
The laboratory is provided with
• A large refrigeration system, able to provide
cold He stream, either supercritical or two
phase, up to 15 g/s at 4.6K, additional
refrigeration power of 500 W at 60-80K,
and 1.5 g/s at 4.6K for superconducting
current leads
• A Power Converter able to provide up to
20kA +/- 25V (or 10kA +/-50V) at 2500A/s
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• A large bore (1150 mm) Nb3Sn CICC
solenoid able to achieve a central field of
7 T at 20 kA, the ENFASI magnet
• A 50 kA Power Converter (+10V)
With such equipment the laboratory can perform several
activities in the field of power superconductivity, ranging from
critical current measurements of CICC power cables (e.g.
fusion magnets cables) to a test facility of magnets (e.g.
accelerator magnets), including several services related to
cryogenic technologies.
Our target is the self sustainability of the laboratory,
according to the funding rules
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INFN targets and equipment
In this joint program INFN defined as its
target the superconducting magnet test
facility, thus INFN has procured and manage:
• the cryogenic plant
• the fast ramped Power Converter
• the superconducting HTS current leads
Of course all these items had also to serve the
ENFASI facility for critical current test.
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Cooling Tower: 20m3/h of
water at 25ºC, 300kW
He gas storage:
V=30m3, P=12bar
Power supply for
magnet biasing:
20kA, +25V/-20V
10kA, +50V/-40V
20kA Current
leads
Gas management
skid
DC Power supply
for samples:
50kA, +12V
Cold Box
200W @4.5K
500W @60K
Connection box
Connection
cryostat
ENFASI magnet:
7 T, 1150 mm
bore
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The cryogenic plant
The minimum ideal
power to be used at RT
for extracting power at
4.6 K is 70 W (RT)/1 W
(4 K). Actually this
figure is much worse,
depending mostly on the
size of the plant: from
8kW/W
for
small
cryocoolers to 300W/W
for large (kW order)
cryogenic plants.
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Actually two preset
refrigeration modes have
been implemented in the
refrigerator
control
system:
1) accelerator dipole;
2) ENFASI magnet;
Either modes foresee the
use of supercritical He
stream at 4.6 K
An additional liquefier mode is also available, as well as a full
manual control of the cold box parameters.
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The power converter
Producer: DANFYSIK A/S
DK-2630 Taastrup, DK
Outputs: 20 kA - 25 Volts
10 kA - 50 Volts
Main Input is 400 Volts ac 3 Phase
Water cooled
The power converter is made of two 10 kA converters that can be
switched in series/parallel to achieve either high voltages (for
SIS300 dipoles) or high currents (e.g. for the ENFASI solenoid).
The controller is able to provide custom current profiles as well as
subsequent cycles of a customized profile for specific applications.
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The current leads: introducing new flexibility
A current lead has the special function to
deliver the power from the room temperature
side to the cryogenic environment. It has great
influence on the cryogenic losses of devices,
and has to be designed carefully. In recent
years the use of HTS have been pursued to
reduce the heat load at low temperature.
It can be found that exists a fixed ratio among the length L and the cross sectional
area S for a current lead connecting two temperatures TH (hot) and TC (cold):
æLö
1
ç ÷ =
è SøOPT I 0 2
ò
l (T)
TH
dT
ò l (T)r (T) dT
being (T) the electrical resistivity of the lead, (T) its thermal conductivity, and
I0 the current flowing into the lead.
TC
2
TH
T
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Combining the Joule effect dissipation QJ and the Fourier heat conduction QF we
have:
T
dT
QF   S
dx
dx 2
QJ   I
S
Q Q 2 I
2
C
Most metals obey to the Wiedemann-Franz law :
QC  I 0

2
H
2

H
TC
 dT
 (T )  (T )  L0 T
L0 TH2  TC2

Vapor cooled leads steady state equation

d 
dT 
dT
I   S
0
  m C P
S
dx 
dx 
dx
2
0
where dm/dt is the cooling gas mass flow rate to be optimized
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Thermal map of the current lead: Left I = 12 kA - Right I = 20 kA +
LN2
Liquid Nitrogen Consumption
10
LN2 Rate (L / h)
8
6
4
20 cm
25 cm
2
14
16
18
Current (kA)
20
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Conclusion
• A large investment for power superconductivity has been
done at University of Salerno site, pushed from ENEA and
INFN needs.
• The new facility can perform accelerator magnet cryogenic
tests, widening the possibilities of the infrastructures
already working in INFN laboratories (Genova and
Milano). It will be ready for magnet test by 2016, and in
2017 the facility for critical current measurement will be
also operational.
• This new laboratory has a self sustainability target, which
means no extra charge for the partners which realized it.
SIF, 22/09/2015