1. Superconductive
Radiation Space
Shielding
for Exploration Missions
R. Battiston
INFN-TIFPA and University of Trento
Italian Space Agency
COSPAR 2014 Moscow
Friday 15 August 14

2. The Consortium
SPA 2012 2.2.02 Key technologies for in-space activities
Friday 15 August 14

3. 3
FP7
SR2S
program
(2013-­‐15)
3
Friday 15 August 14

4. 4
Radia7on
effects
on
biological
7ssues
4
Friday 15 August 14

5. 55
Friday 15 August 14

6. 6
The
interplanetary
travel
case
6
•
The
evidence
for
cancer
risks
from
humans
who
are
exposed
to
low-­‐LET
radia:on
is
extensive
for
doses
above
100
mSv
(10
rem).
•
The
doses
that
are
to
be
expected
on
space
missions,
as
well
as
the
nuclear
type
and
energies,
are
quite
well
understood.
•
The
main
contribu:on
to
the
ionizing
radia:on
encountered
in
space
are
• Solar
Par:cle
Events
(SPE)
• Galac:c
Cosmic
Rays
(GCR)
•
Friday 15 August 14

7. Distribu=on
of
energies
of
GCR.
This
is
a
graph
of
the
more
abundant
nuclear
species
in
CR
as
measured
near
Earth.
Below
a
few
GeV/nucleon
these
spectra
are
strongly
influenced
by
the
Sun.
The
different
curves
for
the
same
species
represent
measurement
extremes
resul=ng
from
varying
solar
ac=vity
(Physics
Today,
Oct.
1974,
p.
25)
Par=cle
spectra
observed
in
SPE
compared
with
the
GCR
spectrum
Friday 15 August 14

8. 8
Galac7c
cosmic
radia7on
8
Friday 15 August 14

9. 9
%
of
death
due
to
cancer
-­‐
95%
CL
9
Durante
&
CucinoUa,
Nat.
2008
Friday 15 August 14

10. 10
Doses
for
explora7on
missions.....
10
• FREE
SPACE:
equivalent
doses
in
excess
of
1.2
Sv
/yr
(∼120
rem/yr)
• SPACECRAFT
(thin)
SHIELDING:
about
700-­‐800
mSv/yr
(70-­‐80
rem/yr)
• ON
THE
MARS
SURFACE:
between
100
and
200
mSv/yr
(10
and
20
rem/yr),
depending
on
the
loca:on
• ON
THE
MOON
SURFACE
:
223
mSv/yr
(22,3
rem/yr)
with
oscilla:ons
of
±
10
rem/yr
as
a
func:on
of
solar
ac:vity
–for
comparison:
ISS
about
18
rem/yr
-­‐-­‐>
6
month
expedi7ons
•
Friday 15 August 14

11. 11
Projec7on
of
risk
of
radia7on
on
11
95%
CL
Friday 15 August 14

12. 12
3%
REID
limit
=>increase
of
P(cancer
death)
12
Friday 15 August 14

13. 13
Mars
Mission
1000
days
in
space
13
Friday 15 August 14

14. 14
SR2S
mission
scenarios
14
Friday 15 August 14

15. 14
SR2S
mission
scenarios
14
Friday 15 August 14

16. 15
Shield
in
space
if
it
is
“thin”
...
.......then
it
“adds”
dose
15
Friday 15 August 14

17. 15
Shield
in
space
if
it
is
“thin”
...
.......then
it
“adds”
dose
15
Friday 15 August 14

18. 15
Shield
in
space
if
it
is
“thin”
...
.......then
it
“adds”
dose
15
Spacecrafts
structures
2 - 6 cm
Al eq
Friday 15 August 14

19. 16
Advanced
materials
can
help
SPE
not
GCR
16
Friday 15 August 14

20. 16
Advanced
materials
can
help
SPE
not
GCR
16
Spacecrafts
structures
2 - 6 cm Al eq
Friday 15 August 14

21. 17
So
we
turn
to
ac7ve
radia7on
shields
17
Friday 15 August 14

22. 18
Ac7ve
magne7c
shielding
18
Friday 15 August 14

23. 19
Magne7c
shield
configura7ons
• The
angular
deflec:on
in
the
magne:c
field
may
be
compared
to
the
kine:c
energy
lost
by
ioniza:on,
where
BL
replace
the
electromagne:c
and
nuclear
radia:on
length
to
characterizing
the
shielding
performance
of
the
material
• Unconfined
Field
(e.g.
Earth’s
field),
very
large
volume
(L),
lower
field
strength
(B)
• Confined
field:
small
volume
(L),
higher
field
(B)
and
larger
mass
19
Friday 15 August 14

24. 20
The
ATLAS
superconduc7ng
toroid
20
Friday 15 August 14

25. 21
Previous
Monte
Carlo
Studies
21
Friday 15 August 14

26. 2222
Ac7ve
magne7c
shielding
• Principle
of
opera=on
• B
field
tangent
to
the
shielded
volume
bends
par7cle
away
• 1)
toroidal
B
field,
orthogonal
to
Hab
axis
• 2)
solenoidal
B
field,
parallel
to
Hab
axis
Friday 15 August 14

27. 23
1)
TOROIDAL-­‐ORTHOGONAL
FIELD
23
eg.
racetracks
toroid
Friday 15 August 14

28. 24
...but
also
24
double
helix donut
double
handle
Friday 15 August 14

29. 2525
2)
SOLENOIDAL-­‐PARALLEL
FIELD
eg.
coaxial
solenoids
Friday 15 August 14

30. 26
...but
also
26
mul:solenoid axial
mul:donut
Friday 15 August 14

31. 27
Shielding
power
:
∫BdL
Re
Ri
For
an
ideal
toroid,
the
shielding
power
is
defined
as
-­‐-­‐>
large
radius
-­‐-­‐>
large
B
we
would
reach
effec:ve
shielding
with
∫BdL≈15
Tm
Friday 15 August 14

32. 28
Magnet
mechanical
structure
28
•
•
P(Pa)
=
B2/
2μo
(T2)
Toroidal field !B non uniform!
1-large inward pressure !structural mass
2-low leakage field
Solenoidal
field
!
B
is
uniform
!
1-­‐large
outward
forces
2-­‐large
leakage
field!
compensaNon
coil
Avoid
stresses
on
superconducNng
cable
!coil
support
Friday 15 August 14

33. 29
SRS2
tradeoff
-­‐>
racetrack
toroid
system
Friday 15 August 14

34. 30
Magnet
mechanical
structure
•
Magnet
design
iteraNons
in
SR2S
•
Structure
design
opNmizaNon:
–minimize
the
material
traversed
by
GCR
to
avoid
secondary
producNon
–maximize
the
BdL
to
deflect
away
Z<3
parNcles
–exploit
the
passive
material
to
absorb
Z>2
parNcles
(stopping
power)
•
Perform
Monte
Carlo
calculaNons
of
the
dose
reducNon
factor
for
GCR
and
SPE
•
Improve
the
use
advanced
materials
and
mechanical
soluNons
to
reduce
mass.
•
Current
design
configuraNon:
BdL
≈
8
Tm
30
Friday 15 August 14

35. 31
Superconduc7ng
cable
for
space
applica7ons
31
Friday 15 August 14

36. 32
Superconductors
for
space
32
Friday 15 August 14

37. 33
Columbus
cable
for
SPACE
applica7ons
FROM
17
TO
10.2
grams,
40%
weight
reducNon
FROM:
3x0,5
nickel
clad
wire
3x0,2
copper
stabiliza:on
TO:
3x0,5
:tanium
clad
wire
3x0,5
alluminium
stabiliza:on
Friday 15 August 14

38. 34
Example
of
mass
op7miza7on
First
Design:
•24
Coils
!
High
loads
on
the
racetrack
! Concentrated
Loads
on
the
Tube
" ! High
Local
DeformaNon
! More
sensiNve
at
mechanical
tolerance
Smart
SoluNon
New
Design:
•
120
coils
! Lower
loads
on
the
racetrack
!
Loads
uniformly
distributed
on
the
tube
! Lower
DeformaNon
! Less
SensiNve
at
mechanical
tolerance
Friday 15 August 14

39. 35
Analy7cal
and
Monte
Carlo
analyses
35
See
M.
Giraudo
talks
Friday 15 August 14

40. 36
Magne7c
shielding
of
a
SPE
event
36
Friday 15 August 14

41. • The
Columbus
habitat
was
surrounded
by
the
full
model
already
used
in
the
past,
without
considering
hydrogen
and
endcaps
• The
density
of
every
component
was
reduced:
– 0%
of
the
total
– 25%
of
the
total
– 50%
of
the
total
– 75%
of
the
total
– Total
(around
315
tons)
Simula:on
varying
the
mass
-­‐
M.
Giraudo,
M.
Vuolo
08/15/14
Friday 15 August 14

42. • Par:cles
were
generated
on
a
cylinder
around
the
habitat
!
No
evalua:on
of
the
radia:on
shielding
at
the
endcaps:
– For
this
reason,
the
obtained
dose
values
are
valid
only
to
perform
a
comparison
between
the
different
studied
configura:ons,
they
are
not
absolute
values
of
dose
per
event
in
space.
Source
08/15/14
Friday 15 August 14

43. • Various
components
of
the
primary
radia:on
field
in
space
par:ally
absorbed
in
the
walls
of
the
spacecrai
• Secondary
radia:on
produced
by
scajering
and
reac:ons
of
the
primary
radia:on
in
the
walls
and
other
materials
within
the
spacecrai
• GCR:
about
90%
hydrogen
nuclei;
9%
alpha
par:cles
and
1%
are
the
nuclei
of
heavier
elements
High
energy
protons
and
neutrons:
• Knockout
and
spalla:on
reac:on
– Built-­‐up
of
light
par:cles
and
heavy
ion
target
fragments
with
high
LET
and
low
ranges.
About
radia:on
field
inside
the
spacecrai
08/15/14
Friday 15 August 14

44. HZE:
predominant
processes
in
their
penetra:on
through
majer
are
energy
loss
through
atomic
and
molecular
collisions,
and
absorpNon
and
parNcle
producNon
from
nuclear
interacNons
with
spacecrai
materials
and
:ssues
•E>100
MeV/u
dominant
reac:on
mode:
fragmenta:on
– Nuclear
absorp:on
cross
sec:on
̴
A1/3
•E<100
MeV/u
dominant
reac:on
modes:
elas:c
scajering,
compound
nucleus
forma:on,
and
excita:ons
of
discrete
nuclear
levels
that
decay
by
gamma
emission
or
par:cle
emission
•Transport
of
HZE
highly
modulated
by
nuclear
reac:ons
in
passing
through
majer
HZE
08/15/14
Friday 15 August 14

45. • In
case
of
thick
shielding
important
source
of
dose
• Low-­‐energy
neutrons
from
evapora:on
processes
where
a
neutron
is
boiled
off
from
the
nucleus
because
it
contains
an
excess
of
energy
from
its
last
interac:on
• High
energy
neutrons
from
high-­‐energy
collisions
(ten’s
of
GeV/nucleon)
where
the
result
of
the
interac:on
is
a
spray
of
nuclear
fragments
and
par:cles
• H
approximately
the
same
mass
as
the
neutron
!
the
best
neutron-­‐scajering
medium
available
– The
hydrogen-­‐bearing
materials
reduce
the
number
of
higher
energy
neutrons
in
the
500
keV
to
20
MeV
energy
range
that
penetrate
the
shield
materials
considered.
In
fact,
the
more
hydrogen,
the
bejer
the
overall
shielding
characteris:cs.
Neutrons
08/15/14
Friday 15 August 14

46. Preliminary
Results
Varying
Mass:
Protons
+
He
GCR
All
doses
presented
are
EffecNve
sex
averaged
doses
according
ICRP123
08/15/14
FIELD
ON
Friday 15 August 14

47. Preliminary
Results
Varying
Mass:
Protons
+
He
GCR
All
doses
presented
are
EffecNve
sex
averaged
doses
according
ICRP123
08/15/14
FIELD
OFF
Friday 15 August 14

48. Preliminary
Results
Varying
Mass:
Ions
(z=3
to
26)
GCR
All
doses
presented
are
EffecNve
sex
averaged
doses
according
ICRP123
08/15/14
FIELD
ON
Friday 15 August 14

49. Preliminary
Results
Varying
Mass:
Ions
(z=3
to
26)
GCR
All
doses
presented
are
EffecNve
sex
averaged
doses
according
ICRP123
08/15/14
FIELD
OFF
Friday 15 August 14

50. Preliminary
Results
Varying
Mass:
TOTAL
dose
08/15/14
Normaliza:on
extended
to
all
the
solid
angle.
Note
that
we
are
genera:ng
par:cles
from
a
lateral
source.
In
this
preliminary
analysis
we
are
not
considering
‘endcaps
effect’!
Friday 15 August 14

51. Dose
Eq.
Results
08/15/14
Friday 15 August 14

52. • Carbon
Epoxy
cylinder
has
the
best
performance
in
reducing
the
number
of
secondary
neutrons
• The
effect
of
Boron
is
not
influen:al
on
the
results
• We
have
to
inves:gate
the
energy
distribu:on
of
neutrons
and
the
cross
sec:ons
for
the
simulated
configura:ons
Cross
sec:ons
comparison
08/15/14
Friday 15 August 14

53. Energy
distribu:on
of
secondary
neutrons
dose
08/15/14
Lin-­‐Log
scale
Negligible
contribuNon
below
100
KeV
Friday 15 August 14

54. Cross
sec:ons
for
different
materials
ENDF-­‐VII
(n,Total)
08/15/14
Friday 15 August 14

55. Considering
different
materials
configura:ons
:
08/15/14
1. Carbon
Epoxy,
same
geometry
(No
Titanium)
• Pb
internal
cylinder
(3
cm
thick
–
75
tons)
• All
Carbon
Epoxy
(Coils
and
structures)
Friday 15 August 14

56. Material
componentMaterial
componentMaterial
componentMaterial
component Other
featuresOther
featuresOther
features
ConfiguraNon COILS STRUCT.
1 STRUCT.
2 Solid
H2
Par:cle Field G4
Phisiscs
List
B4C/Al Coil
Eq.
Mat
Titanium B4C/Al -­‐
H OFF QBBC
C
Epoxy
Coil
Eq.
Mat
Titanium C
Epoxy
-­‐
H OFF QBBC
C
Epoxy
HP Coil
Eq.
Mat
Titanium C
Epoxy
-­‐
H OFF QGSP_BERT_HP
No
Mat Coil
Eq.
Mat
Titanium -­‐ -­‐
H OFF QBBC
Lead Coil
Eq.
Mat
Titanium Lead -­‐
H OFF QBBC
All
Carbon Carbon
Epoxy Carbon
Epoxy Carbon
Epoxy -­‐
H OFF QBBC
Carbon_NoTi Coil
Eq.
Mat
Carbon
Epoxy Carbon
Epoxy -­‐
H OFF QBBC
Hydro+B4C/Al Coil
Eq.
Mat
Titanium B4C/Al 10
tons
H OFF QBBC
Hydro+B4C/Al+Field Coil
Eq.
Mat
Titanium B4C/Al 10
tons
H ON QBBC
C
Epoxy
Field
(H) Coil
Eq.
Mat
Titanium C
Epoxy
-­‐
H ON QBBC
C
Epoxy
Field
(H+He) Coil
Eq.
Mat
Titanium C
Epoxy
-­‐
H+He ON QBBC
C
Epoxy
Field
x2
(H+He) Coil
Eq.
Mat
Titanium C
Epoxy
-­‐
H+He ON
(double) QBBC
08/15/14
STRUCT.
1
Solid
H2
STRUCT.
2
COILS
Friday 15 August 14

57. Effec:ve
Doses:
All
Configura:ons
08/15/14
Freespace
H,
normalized
on
the
lateral
region
(47%
of
total
solid
angle)
Field
Off
Friday 15 August 14

58. 54
Conclusions
(1)
54
•The
SR2S
project
brings
one
of
the
most
challenging
magnet
systems
to
be
built
•Various
of
the
technologies
for
such
a
space
superconduc:ng
system
do
not
exist
yet
•SR2S
is
an
extraordinary
technology
development
field
and
technology
driver
Friday 15 August 14

59. 55
Conclusions
(2)
•Ac:ve
Radia:on
Shielding
for
explora:on
is
a
necessity
•Passive
shielding
for
GCR
is
not
adequate
and
for
SPE
can
only
protect
limited
volumes
•Ac:ve
magne:c
shielding
becomes
effec:ve
at
high
∫
BdL
values
and
only
if
the
material
thickness
traversed
by
the
GCR
is
“small”
•Interplay
between
ac:ve
and
passive
shielding
is
complex
and
detailed
simula:ons
are
needed
to
understand
it55
Friday 15 August 14

60. 56
Conclusions
(3)
•Op:miza:on
of
magne:c
and
structural
forces
is
mandatory
•During
the
first
year
SR2S
has
developed
the
basic
tools
for
ac:ve
shield
analysis,
started
a
sistema:c
inves:ga:on
and
achieved
important
technological
developments
•We
are
analyzing
a
toroidal
configura:on:
other
magne:c
configura:ons
would
also
deserve
careful
study
•A
R&D
path
towards
future
developments
for
light,
high
field,
modular
toroidal
shield
design
has
been
iden:fied
•Collabora:on
and
synergy
with
NASA,
ESA
and
EU
56
Friday 15 August 14

61. • In
order
to
reduce
neutron
contribu:on
we
must
consider
genera:on
and
absorb:on
of
n
in
different
materials
• Heavy
materials
as
lead
(Pb)
have
a
large
absorb:on
cross
sec:on
but
in
case
of
high
energy
protons
(GCR)
they
produce
more
neutrons
(large
secondaries
genera:on).
GeneraNon
>
AbsorbNon
• Boron
rich
materials
are
efficient
neutron
absorber
only
in
the
low
energy
region
where
dose
contribu:on
is
negligible.
08/15/14
Conclusions
(4)
Friday 15 August 14

62. • Using
Carbon
Epoxy
in
place
of
Titanium
reduces
significantly
the
neutron
produc:on
but
increases
protons
contribu:on.
• The
magne:c
field
is
off
in
this
configura:on
and
proton
contribu:on
may
be
decreased
by
the
field.
• The
choice
of
structural
materials
is
fundamental
• Materials
and
field
must
work
in
synergy
in
order
to
improve
the
dose
reduc:on
avoiding
secondaries
produc:on
08/15/14
Conclusions
(5)
Friday 15 August 14

63. Thank you !
Friday 15 August 14

64. 60
backup
60
Friday 15 August 14

65. SC
cables
Friday 15 August 14

66. Friday 15 August 14