REVIEW OF SCIENTIFIC INSTRUMENTS 89, 10K119 (2018)
JET diagnos ic enhancemen s es ing and commissioning
in p epa a ion o DT scien i ic campaigns
J. Figuei edo,1,2,a) A. Mu a i,1,3 C. Pe ez Von Thun,1,4 D. Ma occo,5M. Ta docchi,6F. Belli,5
M. Ga c´
ıa Mu˜
noz,7A. Sil a,2T. C aciunescu,8P. Blancha d,9I. Balboa,10 N. Hawkes,10
I. S. Ca alho,2B. Tal,11 J. Be na do,2,12 I. Zycho ,13 and JET Con ibu o sb)
EURO usion Conso ium, JET, Culham Science Cen e, Abingdon OX14 3DB, Uni ed Kingdom
1EURO usion P og amme Managemen Uni , Culham Science Cen e, Abingdon, Uni ed Kingdom
2Ins i u o de Plasmas e Fus˜
ao Nuclea , Ins i u o Supe io T´
ecnico, Uni e sidade de Lisboa, Lisboa, Po ugal
3Conso zio RFX (CNR, ENEA, INFN, Uni e si a’ di Pado a, Acciaie ie Vene e SpA), Pado a, I aly
4Fo schungszen um J¨
ulich GmbH, Ins i u ¨
u Ene gie- und Klima o schung—Plasmaphysik, Ge many
5Uni `
a Tecnica Fusione, ENEA C. R. F asca i, Via E. Fe mi 45, 00044 F asca i, Roma, I aly
6IFP-CNR, Via R. Cozzi 53, 20125 Milano, I aly
7Uni e sidad de Se illa, Se illa, Spain
8The Na ional Ins i u e o Lase , Plasma and Radia ion Physics, Magu ele, Bucha es , Romania
9Ecole Poly echnique F´
ed´
e ale de Lausanne (EPFL), CRPP, CH-1015 Lausanne, Swi ze land
10CCFE, Culham Science Cen e, Abingdon, Oxon OX14 3DB, Uni ed Kingdom
11Wigne Resea ch Cen e o Physics, P.O. Box 49, H-1525 Budapes , Hunga y
12JET Exploi a ion Uni , Culham Science Cen e, Culham OX14 3DB, Uni ed Kingdom
13Na odowe Cen um Bada´
n Ja˛d owych (NCBJ), 05-400 O wock-Swie k, Poland
(P esen ed 17 Ap il 2018; ecei ed 3 May 2018; accep ed 29 June 2018;
published online 24 Oc obe 2018)
In o de o op imize he scien i ic exploi a ion o JET (Join Eu opean To us) du ing he upcom-
ing deu e ium- i ium expe imen s, a se o diagnos ic sys ems is being enhanced. These upg ades
ocus mainly on he expe imen al and ope a ional condi ions expec ed du ing i ium campaigns. I
should be s essed ha measu emen s ele an o bu ning plasmas a e speci ically a ge ed. P e i-
ously non-a ailable capabili ies, such as a cu en measu emen sys em ully co e ing all poloidal ield
ci cui s, a e desc ibed in de ail. Ins umen desc ip ions, pe o mance p edic ion, es ing, and ini ial
commissioning esul s o hese sys ems a e p esen ed. h ps://doi.o g/10.1063/1.5038548
I. INTRODUCTION
The upcoming JET deu e ium- i ium (DT) campaign,
DTE2, is scheduled o ake place be o e he end o 2020. Fo
many yea s, JET diagnos ics ha e been upg aded in o de o
p o ide adequa e suppo o scien i ic exploi a ion, wi h pa -
icula a en ion o he expe imen al and ope a ional condi ions
expec ed du ing deu e ium- i ium campaigns.1–3Diagnos ic
capabili ies ele an o bu ning plasmas condi ions ha e been
speci ically a ge ed.
II. DIAGNOSTICS UPGRADE FOR OPERATION
The cu en s lowing in he 9 poloidal ield ci cui s (P1,
PFX (Poloidal Field o X poin o ma ion), P4, Imbalance,
Shaping, and D1–D4) a e cu en ly measu ed by h ee di e en
echnologies.4Cu en measu emen d i s ha e appea ed o e
he yea s and no p ope ly ecalib a ed, o igina ing a disc ep-
ancy be ween wo simila measu emen s o abou 6%. E en
wi h a p ope calib a ion, some diagnos ics such as “shun s”
and Rogowski coils (in he in eg a o pa ) su e , o exam-
ple, om empe a u e sensi i i y, which can change s ongly
du ing he campaigns. I he measu emen s a e inaccu a e
No e: Pape published as pa o he P oceedings o he 22nd Topical Con e -
ence on High-Tempe a u e Plasma Diagnos ics, San Diego, Cali o nia, Ap il
2018.
a)Elec onic mail: [email p o ec ed]g.
b)See he au ho s lis o “X. Li audon e al., Nucl. Fusion 57, 102001 (2017).”
(o se s), he e is con lic ing in o ma ion (be ween cu en
and magne ic measu emen s) o he e alua ion o he plasma
cu en p o ile, which leads o inconsis encies be ween he
EFIT (Equilib ium Fi ing code)5 econs uc ed poloidal ield
cu en s and he poloidal ield cu en s measu ed du ing he
discha ge. Rega ding he poloidal ield cu en s acquisi ion
sys em, i would be use ul o ha e a be e empo al esolu-
ion since a s ong coupling be ween he plasma and P1 coil
means ha high cu en s can be induced du ing a dis up ion.
The ea ly phase o he cu en quench las s less han 10 ms a
JET and sees he ise o elec omagne ic o ces as well as un-
away elec on beams. A be e ime esolu ion o P1 cu en
measu emen would imp o e unde s anding o he condi ions
in which unaway elec ons a e c ea ed. Ano he impo an
mo i a ion o acqui e he poloidal ield powe supplies cu en ,
wi h high p ecision and good empo al esolu ion (>2.5 kHz),
is o unde s and how he cen al solenoid and he o he poloidal
ield cu en s d i e he eco e y o he plasma cu en be ween
ELMs and possibly o unde s and be e how he plasma cu -
en suddenly changes as a consequence o an ELM (Edge
Localized Modes). These measu emen s would p o ide a be -
e e alua ion o plasma s o ed ene gy in e -ELM (Wp/Wdia)
and he quan i ica ion o i s d op a e an ELM.
To add ess hese issues, open-loop, open-pa h, Hall e ec
cu en measu emen senso s will be ins alled ully co e ing
all poloidal ield ci cui s. Imaging capabili ies ha e become
an impo an ool bo h ope a ionally and o he p o ec ion
0034-6748/2018/89(10)/10K119/5/$30.00 89, 10K119-1
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10K119-2 Figuei edo e al. Re . Sci. Ins um. 89, 10K119 (2018)
FIG. 1. JET isible wide angle and di e o iews acqui ed h ough op ical
elay.
o plasma acing componen s. An op ical elay sys em has
now been pu in place, and ini ial da a (Fig. 1), o bo h he
wide angle6and di e o 7 ields o iew, ha e been ob ained
du ing sys em commissioning, gua an eeing ope abili y p io
o plasma ope a ions.
The equipmen o he co e ac i e cha ge exchange diag-
nos ic sys em, essen ial o a quali y inc ease o he ion
empe a u e measu emen s, has now been pu in place.8
III. DIAGNOSTIC UPGRADES FOR NEUTRON
DETECTION
A 12-pixel Single C ys al Diamond (SCD) ma ix has
been de eloped and ins alled in he JET oo labo a o y
( adial line o sigh ).9The SCD neu on spec ome e has
been de eloped o 14 MeV neu on measu emen s in DT
plasmas whe e i o e s e y high ene gy esolu ion (abou
1% FWHM) combined wi h a high coun ing a e capabili y
(>1 MHz). Measu emen s o 2.5 MeV neu ons om DD
(Deu e ium-Deu e ium) eac ions ha e shown ha basic neu-
on spec oscopy can be pe o med also o he 2.5 MeV
neu ons. A single pixel SCD was ins alled ea lie in he
beam dump o a neu on spec ome e 10 (wi h an oblique
line o sigh ). Following his ins alla ion, good 2.5 MeV
da a we e collec ed which ha e p o en ha he SCD can p o-
ide use ul in o ma ion on he neu on spec um. In pa icula ,
he diagnos ic can p o ide in o ma ion on non- he mal neu-
on emission caused by Ion Cyclo on Resonance Hea ing
(ICRH). This will comple e he in o ma ion p o ided by he
spec ome e s ins alled wi h a adial line o iew [TOFOR
(Time-O -Fligh neu on spec ome e a Op imized Ra e), dia-
mond ma ix and NE21311,12] and an oblique iew (NE213),
which is impo an in o de o measu e he aniso opici y in he
dis ibu ion unc ion o he hea ed uel ions. SCD spec om-
e e s obse ing he neu on emissions om di e en lines o
sigh in u u e D, TT (T i ium-T i ium), and DT campaigns will
allow o be e sepa a ion o he neu on spec al componen s
[due o he mal Neu al Beam Injec ion (NBI) and ICRH].
In DT plasmas, he SCD neu on spec ome e s will p o ide
in o ma ion on he mal/non- he mal neu on emission, ICRH
as ion ails, and possible ion empe a u e. The ins alla ion o
a emo e con ollable high ol age powe supply and a digi-
ize capable o eal ime analysis o he pulses will p o ide he
capabili ies needed o ope a ions in he coming high powe
FIG. 2. Expec ed neu on spec a wi h di e en componen s du ing he JET
DT campaign o he SCD in oblique line o sigh .
D, TT, and DT campaign. The expec ed neu on spec a o a
SCD in his posi ion a e shown in Fig. 2.
SCD has shown o ha e good esolu ion (Fig. 3) and spec-
al capabili ies able o dis inguish sou ce composi ion. The
esul s shown on Fig. 4a e measu emen s ob ained wi h a SCD
o moni o he gene a o used o 14 MeV neu on calib a ion
a JET.
ToFu is a ully digi al upg ade o he da a acquisi ion
sys em (DAS) o he TOFOR neu on spec ome e 13 a
JET. The ToFu sys em o e s conside able simpli ica ion and
FIG. 3. Single c ys al diamond spec ome e esolu ion.
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10K119-3 Figuei edo e al. Re . Sci. Ins um. 89, 10K119 (2018)
FIG. 4. DT spec al capabili ies o single c ys al diamond.
enhancemen s o he pe o mance o he spec ome e , wi h
highe da a quali y and imp o ed physics analysis. The
imp o ed physics possibili ies include imp o ed backg ound
supp ession ha makes he spec ome e sensi i e o e en
weake emission componen s in he spec um, he eby imp o -
ing he possibili ies o s udies o ICRH and MHD physics,
as well as exo ic neu on p oduc ion channels. The sha pe
esponse unc ion opens up o simul aneous measu emen s o
he weak DD emission in DT domina ed plasmas. Thus, in es-
iga ion o ITER- ele an me hods o uel ion densi y a io
de e mina ion will be possible, along wi h he po en ial o dis-
en angle he beha io D and T sub-popula ions in DT plasmas.
Implemen a ion o new on-line da a acquisi ion and educ ion
modes, in pa icula in DT, could inc ease conside ably he
o al numbe o e en s pe sho ha he sys em can s o e, hus
imp o ing he s a is ical accu acy o he measu emen s. A
p esen , he ToFu sys em is limi ed o 20 acquisi ion channels
wi h some o he 37 de ec o s o he TOFOR spec ome e ha -
ing o sha e channels. Fu he mo e, i is dependen on con ol
signals supplied om he TOFOR DAS sys em. The e o e he
ToFu sys em will be expanded o equip e e y de ec o wi h
i s own acquisi ion channel while in eg a ing i in o JET da a
acquisi ion and con ol sys ems. This will make he sys em
uly independen o he TOFOR DAS, da a will become com-
monly a ailable, and sys em o e all eliabili y will inc ease.
The simula ed esponse unc ions o TOFOR and ully digi al
(ToFu) acquisi ion sys ems a e shown in Fig. 5. The long ails
cha ac e is ic o TOFOR o bo h 2.5 and 14 MeV neu ons
a e ackled by ToFu.
FIG. 5. Simula ed esponse unc ions o TOFOR and ully digi al (ToFu)
acquisi ion sys ems.
FIG. 6. Bic on BC418 i on bu n up expe imen al signal da a added h ough
se o pulses.
Ini ial da a ob ained wi h he Bic on BC418 de ec o s14 o
he neu on came as, a e ins alla ion o he new digi al acqui-
si ion sys em, show he i on bu n up signal added h ough a
se o pulses o s a is ical pu poses (Fig. 6).
IV. DIAGNOSTIC UPGRADES FOR ALPHA PARTICLES
JET has an excellen se o con ined alpha-pa icle diag-
nos ics, which comp ise gamma- ay spec ome e s, KM6S-1
( e ical iew), KM6S-2 ( e ical iew), and KM6T (quasi-
angen ial iew) o measu ing ene gy dis ibu ion o as ions
and a 2D neu on/gamma- ay came a o omog aphic econ-
s uc ion o he alpha-pa icle sou ce and he empo al e o-
lu ion o i s spa ial emissi i y.15 The easibili y o alpha- ay
measu emen s depends on e iciency o he neu on supp es-
sion. Also, i is impo an o a oid ca bon-con aining ma e ials
in he neu on a enua o because he inelas ic sca e ing o
neu ons wi h ene gy exceeding 5 MeV, 12C(n,n’gamma)12C,
leads o he unwelcome backg ound o 4.44-MeV gamma ays.
The bes neu on a enua o is 6LiH, bu LiH wi h a na u al
Li composi ion could be used as well. I is compac , e ec-
i e, and well anspa en o MeV gamma- ays. I does no
p oduce in e e ing gamma- ays in he high-ene gy ange. A
30-cm sample o he 6LiH- il e educes he 2.5-MeV neu-
on lux ≈900 imes and he 15-MeV neu on lux ≈30 imes.
The a enua o has been es ed in JET expe imen s wi h deu-
e ium plasmas. Assessmen s o he gamma- ay backg ound
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10K119-4 Figuei edo e al. Re . Sci. Ins um. 89, 10K119 (2018)
educ ion in he ene gy ange below 3 MeV ga e a ac o o
100. A small educ ion o he spec a ( ac o o 2) was ound in
he ene gy ange abo e 3 MeV, due o he Gamma- ay ans-
pa ency o he 6LiH-a enua o . The KM6S-1 de ec o (JET
Oc an 8) wi h a LaB 3(Ce) scin illa o is iewing he plasma
cen e e ically h ough 2-m collima o s. A simila de ec o ,
KM6S-2 (JET Oc an 5), is pe manen ly eco ding he spec a
iewing he plasma cen e h ough a 30-cm 6LiH a enua o .
Fo he DT ope a ion, an addi ional 30-45 cm LiH a enua o
is needed o alpha-pa icle measu emen s in DTE2. A new
LiH a enua o will be ins alled inside he exis ing S ainless
S eel (SS) collima o (a e sui able modi ica ions). In Fig. 7,
he posi ion o he de ec o and a enua o ela i e o he JET
essel is shown.
The gamma came a16–18 esul s ha e been ob ained o
gammas gene a ed by unaway beams (Fig. 8). This has been
done wi h he CeB 3p o o ype de ec o s ( he inal de ec o s
use LaB 3c ys als) ha we e ins alled be o e he beginning
o he las expe imen al campaigns. This p o ides suppo o
upcoming s udies bo h a JET and in e na ionally.19–21
FIG. 7. Gamma ay de ec o and a enua o posi ion ela i e o JET.
FIG. 8. Measu emen s o gamma ays gene a ed by unaway elec ons.22
FIG. 9. Gamma came a calib a ion spec a.23
FIG. 10. Recons uc ed pulse heigh spec um o he LaB 3in insic ac i i y.
All he CsI de ec o s ha e now been eplaced wi h LaB 3.
The inc eased capabili ies o he sys em now allow measu ing
calib a ion sou ces ha we e p e iously no de ec ed (see Ba
peaks in Fig. 9).
CeB 3and LaB 3p o ed o ha e e y simila cha ac e -
is ics wi h he decision o choose LaB 3being mainly due o
he in insic ac i i y his c ys al has. This ac can be use ul
o calib a ion pu poses. The ob ained spec a o he LaB 3
in insic ac i i y is show on Fig. 10.
V. INSTABILITIES DIAGNOSTIC UPGRADES
A JET, he edge elec on densi y p o ile can be mea-
su ed by a Li beam diagnos ic (schema ic o he sys em in
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10K119-5 Figuei edo e al. Re . Sci. Ins um. 89, 10K119 (2018)
FIG. 11. Schema ic o he Li Beam diagnos ic sys em a JET.
Fig. 11) along a e ical line (R = 3.252 m) in oc an 7 ×24
spa ial channels wi h esolu ion o 1 cm (mapped on o he
midplane).
The educ ion in he exis ing Li beam cu en wobbling,
by emo ing he ing ans o me om he so i on shield and
e-a anging he hea ing cables, will be essen ial o blob in es-
iga ion by educing an in ense equency peak in he spec al
egion o in e es o such s udies and allow a as e and sa e
eplacemen o he ion gun, which could be pe o med in
½
h
a he han 2 h. In his way, educing he exposu e o s a o
high ac i a ion a e high le el NBI discha ges and T expe -
imen s would minimize he impac on JET ope a ion ime,
educe he powe losses in he ans o me chain, and p o ide
inc eased ope a ional space o he hea ing, which would ex end
he use ul ope a ion ime o he ion gun. Fu he mo e, ELMs
can ha e a signi ican impac on he de ec ed backg ound ligh
le els. Thus, his should be moni o ed, i.e., beam chopping is
needed o backg ound measu emen s on ime scales o in e -
es . Fo JET, pedes al analysis in e ELM p o iles a e ypically
eques ed. Conside ing he maximum epe i ion equency o
ELMs (e.g., in he case o high gas injec ion), beam chop-
ping should be ca ied ou wi h 10 kHz equency (a p esen ,
his can only be pe o med up o 100 Hz). The inc ease in
he cu en ou pu o ≈100 mA will be achie ed by wo new
powe supplies and u he sligh modi ica ions o he sys em
will allow chopping wi h 10 kHz equency and wi h only
mic osecond long ise ime. O he upg aded diagnos ics such
as he TAE (To oidal Al ´
en Eigenmodes),24 he Fas Los Ion
De ec o 25 and e lec ome y sys ems26 ha e al eady ob ained
expe imen al esul s du ing he las campaigns.
ACKNOWLEDGMENTS
Wi h his se o diagnos ics, JET is in he p ocess o
concluding an enhancemen s p og amme ha has p epa ed
his de ice o upcoming DT campaigns. This wo k has been
ca ied ou wi hin he amewo k o he EURO usion Con-
so ium and has ecei ed unding om he Eu a om esea ch
and aining p og amme 2014-2018 unde G an Ag eemen
No. 633053. The iews and opinions exp essed he ein do no
necessa ily e lec hose o he Eu opean Commission.
1A. Mu a i e al.,Plasma Phys. Con olled Fusion 47, B249 (2005).
2V. Kip ily e al.,AIP Con . P oc. 1612, 87 (2014).
3J. Figuei edo, Re . Sci. Ins um. 87, 11D443 (2016).
4R. Salmon e al.,Fusion Eng. Des. 98, 1148 (2015).
5D. P. O’B ien e al.,Nucl. Fusion 33, 467 (1993).
6M. Cle e e al.,Fusion Eng. Des. 88, 1342 (2013).
7I. Balboa e al.,Re . Sci. Ins um. 83, 10D530 (2012).
8N. Hawkes e al.,Re . Sci. Ins um. 89, 10D113 (2018).
9A. Mu a o e al.,Re . Sci. Ins um. 87, 11D833 (2016).
10C. Cazzaniga e al.,Re . Sci. Ins um. 85, 043506 (2014).
11B. Esposi o e al.,Re . Sci. Ins um. 75, 3550 (2004).
12A. Zimbal e al.,Re . Sci. Ins um. 75, 3553 (2004).
13M. Ga u Johnson e al.,Re . Sci. Ins um. 77, 10E702 (2006).
14L. Giacomelli e al.,Phys. P ocedia 62, 124 (2015).
15V. G. Kip ily e al.,Nucl. Fusion 42, 999 (2002).
16I. Zycho e al.,Phys. Sc . 91, 064003 (2016).
17D. Rigamon i e al.,Re . Sci. Ins um. 87, 11E717 (2016).
18M. Nocen e e al.,Re . Sci. Ins um. 87, 11E714 (2016).
19D. C. Pace e al.,Re . Sci. Ins um. 87, 043507 (2016).
20A. Dal Molin e al.,Re . Sci. Ins um. 89, 10I134 (2018).
21M. Nocen e e al.,Re . Sci. Ins um. 89, 10I124 (2018).
22A. U ban, p i a e communica ion (2018).
23D. Rigamon i e al.,Re . Sci. Ins um. 89, 10I116 (2018).
24F. Nabais e al.,Nucl. Fusion 58, 082007 (2018).
25V. G. Kip ily e al.,Nucl. Fusion 58, 014003 (2018).
26J. C. Hillesheim e al.,Phys. Re . Le . 116, 065002 (2016).
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