ZAO NEG Technology in Fusion
Energy Applications

Vacuum Technology Division

Vacuum Technology Division

Content

 Vacuum Systems Challenges in Fusion Energy
 ZAO NEG pumps characteristics in Fusion Energy
 Applications
 NEG basics
 Conclusions
 New vacuum trends
making innovation happen, together

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Vacuum Technology Division

Content

 Vacuum Systems Challenges in Fusion Energy
 ZAO NEG pumps characteristics in Fusion Energy
 Applications
 NEG basics
 Conclusions
 New vacuum trends
making innovation happen, together

12/11/2021

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Vacuum Technology Division

Thermonuclear Fusion: a new promising and powerful energy source
Fusion Energy is based on the thermonuclear reaction of hydrogen isotopes fuels in aplasma
In stars, the huge gravity allows confining atoms and to produce energy by fusion at about
15 million °C
The thermonuclear reactors developments started in 50’s-70’s to reproduce the energy
production mechanisms inside stars

The most promising fusion reaction on earth involves D and T to produce He and highly
energetic neutrons
To get the confinement and plasma process of H2 isotopes in thermonuclear reactors, 3main aspects must be fulfilled
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 Make the reaction in vacuum (backgound pressure at least 1e-5 Pa) Utilize refilling sources of H2 isotopes and pump exhaust to keep stable plasma Use of powerful magnets to confine the plasma
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Vacuum Technology Division

Vacuum Systems Challenges in Fusion Energy The vacuum characteristics of fusion energy process in stars vs thermonuclear reactors are In thermonuclear reactors vacuum conditions must be generated from scratch H2 isotopes are confined by gravity inside stars, in thermonuclear reactors H2 isotopes repulse
each other and escape from the plasma Escaped isotopes can destabilize plasma process and therefore production of energy The pressure has to be kept constant against a certain re-fuelling rate of H2 isotopes

 In the vacuum systems of thermonuclear reactors, 2 different aspects must be addressed Base pressure in high vacuum level, e.g. at least 1e-6 Pa
 Large pumping speed for H2 isotopes to either keep stable fluxes or absorb escaped H2 isotopes

 The thermonuclear reactors consist of main vessel where plasma process occurs and the produced energy is absorbed & distributed
 several subsystems for plasma heating and confinement, and keep adequate vacuum conditions

 The background gas are mainly H2, water and CO/CO2
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 Hydrocarbons and air are excluded from the application
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Vacuum Technology Division

Vacuum Systems Challenges in Fusion Energy: subsystems
ReactorSide view

Top view

Divertor

 The divertor collects the waste ofmaterials used in the plasma process
such as H2 isotopes
NBI Neutral Beam of H2 and D2 is injected
inside the thermonuclear reactor to«heat» the plasma process

ICRH During the experiment, gas isscattered and must be pumped

DIVERTOR

ECRH/ICRH

DIVERTORDiagnostics

 Diagnostics are used to inspect the plasma process H2 can back stream in diagnostic ducts and must bepumped

Storage and release of hydrogen isotopes
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 H2
 H2 isotopes must be selectively pumped and released
isotopes are produced and mixed to 4HeECRH

 The ECRH/ICRH works in the range of1e-6 Pa Between reactor and ECRH diamondwindows can be used to prevent backstreaming of H2 isotopes

 Sometimes, windows are not usedand high flux of H2 can back stream

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Vacuum Systems Challenges in Fusion Energy: vacuum requirements
NBIDivertor

ECRH/ICRH

Diagnostic

H2 storage and release

Vacuum background (Pa) - main gas

1e-6 - H2

1e-6 - H2

1e-6 - H2, H2O

1e-7 - H2, H2O

1e-7 - H2, H2O

H2 isotopes level during operation (Pa)1e-21e-3÷11e-5

1e-2

1e-2***

Required H2 isotopes pumping speed (l/s)

10.000÷6M*

10.000÷1M*

Distributed pumping

1.000

NAN****

Required H2 isotopes capacity (Pa·l)**10M÷1.000M

1M÷10.000M

2k10kNAN***** The pumping speed depends on NBI and Divertor volumes and Pumps Conductance**The required capacity is calculated for 5 days of operation***The pressure indicates the H2 isotopes value at ppb level in He4 gas stream****In the storage and release of H2 isotopes, NEG “bed” must be considered which can enhance the probability to capture H2isotopes in a large gas stream flux

Takeaways

 In thermonuclear reactors subsystems, the required pumping speed and capacity of H2 isotopes are verysignificant

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 The required pumping speed and capacity must be considered as distributed inside the vacuum systems
 Given the large amount involved, the pumping system must be able to store and release H2 isotopes bycontrolled process

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Vacuum Technology Division

Vacuum Systems Challenges in Fusion Energy: available pumping technologies
Cryo pumpmaking innovation happen, together

Ion pump

TMP

NEG pump (CapaciTorr Z400)

Cryo pump

Ion pump 500

TMP 300

CapaciTorr Z400

Dim. (cm)20 Ø x 53

52 x 45 x 30

25 x 2113 x 3.5

Weight (kg)12120

200.2 kg

Pumping speed for H2 (l/s)

300

500

500

500

Power consumption (W)2200

0.035-0.35

350

 Pumping technologies must be compared in terms of performances vs (dimension, weight, pumping speed,
Power consumption)

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Vacuum Technology Division

Vacuum Systems Challenges in Fusion Energy: available pumping technologies
Cryo pump

Ion pump

Thermonuclear reactor requirements

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TMP

NEG pump (CapaciTorr Z400)

Ion pump

TMP

Cryo pump

NEG pump

Large H2 isotopes pumping speed



 *

Large H2 isotopes capacity



NAN



Magnetic field and radiation compatible









Controlled release of H2 isotopes

NANNAN*It depends on cryogenic temperature NEG pumps are compliant with main thermonuclear reactors requirements in fusion energy applications
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Vacuum Technology Division

CONTENT Vacuum Systems Challenges in Fusion Energy
 ZAO NEG pumps characteristics in Fusion Energy
 Applications
 NEG basics
 Conclusions

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Vacuum Technology Division

NEG & Fusion Research Examples of NEG application in fusion research date back to the 70’s and 80’s
 1976 – ASDEX : SORB-AC® cartridges in the ASDEX divertor: study commissioned by the Max Planck Institut fürPlasmaphysik (1) 1983 – TFTR Princeton : St101® (Zr-Al) Wafer Modules in the plasma chamber (2) 1986 – JET ICRF : NEG pumps in the Antenna Vacuum Transmission Lines (3) More recently, new interest has aroused about the use of NEG in fusion research: 2006 – ENEA Frascati : NEG was used to enable the detection with conventional QMS of 4He / 3He in gas
mixtures rich of D2 / T (4) 2014  DEMO NBI (5) 2018 – LHD at NIFS: installation of a large array of 42 NEG pumps in the divertor completed. Testing isunderway (6) 2019 – ITER tested NEXTorr HV200 for the ECRH and first batch of 16 units is used in the first transmission line 2020 – SWISS Plasma Center tested CapaciTorr HV1600 at TCV (7)making innovation happen, together

12/11/2021(1) M.Borghi and B.Ferrario, Use of non-evaporable getter pumps in experimental fusion reactors, J. Vac. Sci. Technol. 14(1) (1977) 570-574.
(2) J.L. Cecchi et al., Initial limiter and getter operation in TFTR, Journal of Nuclear Materials, 128 & 129 (1984) 1-9.
(3) C. I. Walker, A.S. Kaye, R.A. Horn, F. Mazza, Non-Evaporable Getter Pumping For JET ICRF Antennae, Proceed. 14th Symposium on Fusion
Technology, Avignon (France), September 1986 PP. 815-820(4) A. Frattolillo, A. De Ninno, A powerful tool to quantitatively detect tiny amounts of 4He in a deuterium rich background for fusion
research, Proceedings of the 22nd IEEE/NPSS Symposium on Fusion Engineering - SOFE 07(5) F. Siviero et al., Characterization of ZAO® sintered getter material for use in fusion applications, Fusion Eng. Des. 146 (2019) 1729-1732(6) G. Motojima et al., New installation of in-vessel Non Evaporable Getter (NEG) pumps for the divertor pump in the LHD, Fusion Eng. Des.
143 (2019) 226-232(7) M. Baquero-Ruiz et al., Non-evaporable getter pump operations in the TCV tokamak, Fusion Eng. Des. 165 (2021) 112267
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Evolution of NEGs: what’s changed from70’s to today…
Compressed NEG St707 and St101 on constantan
substrate in ASDEX, TFTR and JET

Porous sintered ZAO disks in LHD, NBI DEMO, ITER
ECRH, SPC
To overcome the limitations of compressed powder pumps,
SAES introduced in the 90s’ the use of sintered disks as mainbuilding block of a NEG cartridge.

compressed pellets/disks

coated strips

getterparticlesgettersupport St707 and St101 have shown a release ofparticulate after few cycles of H2 regeneration
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Sintering is high temperature metallurgical process (belowmelting point) to consolidate, by surface melting, powders intoa single body.
In normal applications the aim of the sintering process is tocreate an extremely dense product, close to what can beachieved by cast melting.
In the case of a NEG material the objective is just the opposite:“ to consolidate powders leaving an extremely porous and open
structure with a large internal surface area which can effectively
capture molecules.” Therefore the process has to be optimized tobound grains leaving large voids…
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Vacuum Technology Division

SAES in NEG & Fusion Research HORIZON 2020 – TFV project – Sub-project V: Vacuum Systems
 task 1.3.6 “Development of a NEG-based pumping concept for NBI pumping (NBI)” SAES worked with RFX-consortium and KIT at :
 demonstrating to be able to scale the performance of a “small” pump to a very large one working inconditions relevant for a NBI system building a NEG mock-up of about 45 m3/s for D2 at 1e-2 Pa (2018)
 Testing at KIT in the TIMO system (2019)

 ObjectivesValidate models describing:Sorbed quantity ∆q [Torr·l/g]
Pumping speed evolution S(∆q) [l/s]
NEG regeneration: residual q0 , gas quantity extracted, pressure
Test pump robustness and performance evolution with cycles
Test engineering solutions: mounting and heating, mechanical/electrical design, remote handling solutions,
redundancy (ideal target: 10/20y maintenance free system !) Define specific quantities for the use in NBI: pumping speed for pump dimension and weightmaking innovation happen, together

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Vacuum Technology Division

SAES in NEG & Fusion Research
Target Application Requirements

 Large pumping speed for H2 and its isotopes: several tens of m3/s
 Large gas load : flux up to tens of Pa m3/s, pressure up to 10-2 Pa range
 Hydrogenation-DeHydrogenation (HDH) cycles at several Torr·l/g
Outline Why NEG ?
 Pumping properties for H2 and D2
 Speed vs pressure
 Speed vs concentration
 Equilibrium pressure
 HDH fatigue test Regeneration

 Towards a full-scale pumping solution

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 Scaling properties from getter disk to small and large-scale pump Working scenarios: matching speed, gas load, duty cycle and regeneration
requirements

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Vacuum Technology Division

Why considering a NEG solution?
 High affinity for hydrogenic species
 pumping speed per unit area

 Large capture capacity for hydrogenic species
 less frequent regeneration cycles
 promising system availability

 Passive pump
 Exempt from faults during operation (e.g power outage: NEG keeps onpumping, no H2 release) Simple integration (vacuum feedthroughs) also improves reliability
 less design constraints

 RT < Operating temperature < 150°C
 No issue with stray electrons and radiative heat exchange No freezing of beam line components

 Commercially available product : modularity of NEG elements (disks) Potentiality to build an extremely large tailor-made pumpmaking innovation happen, together

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Vacuum Technology Division

ZAO-HV getter disks
 Proprietary* quaternary alloy : Zr V Ti Al Sintered getter: robust and extremely low particle release Dimensions:External diameter : ~ 24,3 mm
Internal diameter : ~ 6,2 mm
Height : ~ 2 mm
Weight : 3,5 g

 Standard activation temperature : 450 - 550°C

 Grouped in stacks with 0,5 – 1 mm spacing

making innovation happen, together* Patented alloy: European patents 2,745,305 and 3,071,720
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Vacuum Technology Division

Pumping properties of ZAO getter disks
ZAO-HVDSK- ASTM
curvespressurefor H2 ofatHdifferent
H2 pressures
Pumping speed
vs sorbed
quantity
at different
2
1.33e-4 Pa
1.33e-3 Pa

Pumping Speed (a.u.)

1.33e-2 Pa
1.33e-1 Pa

Sorption temperature: 25 CFirst Activation : 550 C x 60 min.
Reactivations: 550 C x 60 min.

1.0E-07

1.0E-06

1.0E-05

1.0E-04

1.0E-03

1.0E-02

1.0E-01

1.0E+00

Sorbed Quantity (Pa m3)
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 H2 pumping speed of ZAO sintered porous disks shows significant value also at higher pressure values 30-40% decrease is measured compared to the nominal pumping speed in the range (1e-4÷1e-1) Pa17

Vacuum Technology DivisionPumping properties of ZAO getter disks
ZAO-HVDSK- ASTM
curvespressure
for D2 at
D2 pressures
Pumping speed
vs sorbedquantity
at differentof Ddifferent
2
1.33e-4 Pa
1.33e-3 Pa

Pumping Speed (a.u.)

1.33e-2 Pa
1.33e-1 Pa

Sorption temperature: 25 CFirst Activation : 550 C x 60 min.
Reactivations: 550 C x 60 min.

1.0E-07

1.0E-06

1.0E-05

1.0E-04

1.0E-03

1.0E-02

1.0E-01

1.0E+00

Sorbed Quantity (Pa m3)
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 Similar behavior is observed for D2 at higher pressure values

18Vacuum Technology DivisionRegeneration mechanism:
equilibrium pressure of ZAO getter disks
ZAO - HYDROGEN EQUILIBRIUM ISOTHERMS(powder - tests on O-11-50 ring)
1.E+01

D2

H2

Equilibrium pressure (Torr)

1.E+00600 C

1.E-01

1.E-02500 C
400 C
1.E-03200 C
1.E-04300 C

1.E-050.11101001000

Hydrogen concentration (Torr.l/g)
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 Little difference for H2 and D2: max 20%
 No hysteresis observed under repeated adsorption-desorption runs

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Vacuum Technology Division

Mechanical properties of ZAO getter disks
 Requirements related to Hydrogen embrittlement
 “Single shot” limit: dose H2 until the disks loose particles or cracks appear
 “HDH” cycle limit: adsorption-desorption cycles at a given concentration••••

5 disk stack

Dose H2 (10 Torr·l/g)
Vibration 33 Hz – 5mm stroke
Check for dust / cracks
Next dose•

Stack 1 : dose H2 (15 Torr·l/g)•Stack 1 reactivation & Stack 2 sorption•Stack 2 reactivation & Stack 1 sorptionmaking innovation happen, together

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Vacuum Technology Division

Mechanical properties of ZAO getter disks Hydrogen Embrittlement: ZAO-HVdisk
are very robust!
ZAO- HYDROGENEQUILIBRIUM ISOTHERMS(powder - tests on O-11-50 ring)
1.E+01

D2

H2

Equilibrium pressure (Torr)

1.E+00

1.E-01600 C

1.E-02

No problem expected in NBI
applications
working in the Sieverts 500zoneC(≤10 Torrl/g)

HDH cycle
limit:>14 Torrl/g
400 C 1000 cycles

Single-shot
embrittlement
limit: about
100 Torrl/g

1.E-03200 C1.E-04

300 C

1.E-050.1

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1101001000

Hydrogen concentration (Torr.l/g)

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Vacuum Technology Division

Scaling : thermal Case of the mock-up (34 cartridges) already studied by RFX

Activation parameters:
4,8 A, 95V
About 15,5 kW total
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Courtesy of E.Sartori, Consorzio RFX
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Vacuum Technology Division

CONTENT Vacuum Systems Challenges in Fusion Energy
 ZAO NEG pumps characteristics in Fusion Energy
 Applications
 NEG basics
 Conclusions

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Vacuum Technology Division

Large pumping speed in fusion energy Large NEG pump of 34.000 l/s for H2 has been developed inside Eurofusion collaboration
with RFX and KIT
 The pump has been developed ad pumping system of DEMO NBI
 NEG pump shown stable performonaces
 After several cycles of sorption/desorption of H2 and D2
 Under different temperature (40-210°C range), pressure (6 – 100 mPa) and load (0 – 11 torr·l/g)

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Vacuum Technology DivisionZAO NEG pump: an extreme flexible pumping system at LHD (NIFS)
Smart distribution inside the divertor region

Installation region - Divertor

3 NEG wafer modules support

 42 flangeless ZAO wafer modules have been distributed in the divertor at LHD
 The modules are exposed to H2 injection at a peak pressure in the range 1e-3 ÷ 0.1 Pa
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Courtesy of Gen Motojima, engineering and vacuum group at NIFS
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Vacuum Technology Division

NEXTorr HV 200 @ ECRH ITER transfer line

 NEXTorr HV 200 can keep pressure at 2e-8 mbar in 1.7 m3 volume chamber Leak rate <1e-9 mbar l/sec
making innovation happen, together

Courtesy of Shaun Hughes and David Laugier, ITER organization, Cadarache
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Vacuum Technology DivisionContent

 Vacuum Systems Challenges in Fusion Energy
 ZAO NEG pumps characteristics in Fusion Energy
 Applications
 NEG basics
 Conclusions

making innovation happen, together

12/11/2021

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Vacuum Technology Division

Non Evaporable Getters: Basics
 NEGs are reactive metals or alloys which capture
active gases, such as H2O, CO, CO2, O2 and N2 by achemical reaction on their active surface

 The reaction generates carbides, oxides and nitrides
on the getter surface: gases are permanently removed
from the vacuum system

 Hydrogen does not react to form a chemicalcompound but dissolves in the bulk of the getter
forming a solid solution

 A getter does not pump noble gases as they do notchemically reactmaking innovation happen, together

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Vacuum Technology Division

NEG operation
Operating a NEG is simple:

 Step 1: heating under vacuum: ACTIVATION AND REGENERATION
Typically starts at 10-6 TorrModest activation temperature: 40 – 400 W, roughly 500-600 °C
ACTIVATION: 60 minutes standard
 REGENERATION: 5-10 hours depending on experimental conditions

 Step 2: Enjoy!
After the activation or regeneration, the pump absorbs gases at room
temperature without requiring power (surface absorption)

 When the surface capacity is reached (or after a venting), the pump must bereactivated. Repeatable many times (at least 100)

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NEG saturatedC12/11/2021

NO

HNEG underactivation

NEG active and operating
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An example: standard activation
Standard activation of a NEG pump
Regeneration will last longer and will present broader first peak
Pump down &bake out

NEGActivation
1 hour

Cool down
to RT

10-2

Pressure (mbar)

10-3
10-4
10-5
10-6
10-7

NEG
450-500 °C

10-8
NEG @ RT

10-9
making innovation happen, togetherTime
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Vacuum Technology Division

Non Evaporable Getter Pumps: When
NEG pumps are the most suited candidate in all those systems where the following
requirements need to be fulfilled: Clean Ultra High Vacuum (UHV) and more “tough” high vacuum conditions
 High pumping speed for H2 and all active gases (H2O, O2, CO2/CO, N2)
 Reduced footprint and light weight Passive and constant pumping speed
 Absence of vibrations
 Absence of maintenance Reduced or absent power consumption
 Reduced or absent magnetic interference
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NEGs are therefore the most suited choice for a wide variety of UHV and highvacuum systems, from research field to industry applications
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Vacuum Technology DivisionConclusions
 Thermonuclear reactors are promising facilities for clean and powereful energy source Reactors and their subsystems need large pumping speed and capacity for H2 isotopes
 ZAO NEG alloy represents a sutainable pumping solutions with stable and constantpumping performances for H2 isotopes after many cycles of regeneration ZAO NEG pumps represents a flexible solution which can be distributed directly inside
the fusion energy reactor and its subsystems

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Vacuum Technology Division

New trends and challenges in vacuum technology
Cold atomic trap

10-20 mm Ø

Courtesy of Dr. Tristan Valenzuela,
Univ. of Birmingham for the EU FETOpen project iSense (grant no. 250072)

MBE - Semicon

Synchrotronsappl
ispace c-Portability of experiment-high speed/dimension
ratioInterferometer

VacuumTrendsMirror & Monochromator-More the systems are complex., wider isthe operating pressure range-In complex devices no back out,
therefore wide variability vs time

Fusion Energy

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Large vacuum device requires-high capacity for all gases-optimized distribution along
the large vessels

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Vacuum Technology Division

Non Evaporable Getter adressing new trends in vacuum technology
100 l/s in 2.2 kgCompact distribution @SWISSFEL

CF35 flange
500 l/s

4000 l/s in interferometer

NEG &Vacuum
TrendsHigher OLED luminescence

25 cm

34.000 l/s in 100x70 cm

making innovation happen, together

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Thank you foryour attention

www.saesgroup.com

Enrico Maccallini
enrico_maccallini@saes-group.com