The ISTTOK Heavy Ion Beam Diagnostic

HIBD concept

Multiple cell detector(Secondary ions)

Toroidaldirection

Primary beam detector

PlasmaBT

I+

I++

secçãodo feixe

detectorde intensidadee posição

fenda

plac

as c

ondu

ctor

as

I+++

HIBP concept

ISTTOK magnetic configuration

R

bobines toroidais

câmara

secçãocondutora

aberturainterna

Plan view

z

z

xR

RBB c

Toroidal field inside the coil aperture =

x

z

Side section

ISTTOK magnetic configuration

z

z

RR

rR

xR

RBB

ext

extc

)(

)(

int

Toroidal field outside the coil aperture (x) =

22)( yxxr c

xc

EYya

YyaK

YyaIB oy 22

222

22 )()(

)(

)()(

22

1

; ; z

BBxR

BB zx

E

Yya

YyaK

Yya

YyIB o 22

222

22 )()(

)(

)()(

)(22

1

22)( zxR

; d sin1 ; sin1

22

0

22

0 22

E

dK

1222 )()(4

Yyaa

Position coils field

Plasma current magnetic field

plasma outside 2

plasma inside 2).(2

0

r

IB

rdrrjr

B

pp

r

p

; ; r

xBB

r

yBB pypx

Asymmetric current profiles are generated

by a combination of symmetric profiles

For radial profiles

z

z

R

rrj

m

p

2

2

1)(

) sin() cos(2

)(3242

2242

tm

Ft

m

Ft

m

Ftti

m

Fiti ioioiioi

oiio

o

Beam trajectories

; ; )( ; vv2

2

22

3

3

i)1()2(0)2()1(0 Bm

qEBB

m

qBBqF iiiiiio

i x,y,z

In numerical simulation equations uses constant B and E;

B and E are updated on each iteration cycle (toroidal curvature negleted);

Electric field are modelled freely (core and edge) – normally an inverted parabola with peak eV ~ 3/2 KTe

Cs+20 keV

Cs++

plasma

coils

-32

-30

-28

-26

-24

-22

-20

5.7 6.1 6.5 6.9 7.3

z-deviation (mm)

y-de

tect

or (c

m)

Cross section front view

Detector arrangement

Detector configurations A, B, C

Beam attenuation

MOST IMPORTANT IONIZATION REACTIONS:

I+ + e- I2+ + 2e- I+ + e- I3+ + 3e- I2+ + e- I3+ + 2e-

I I

j o e e

AR

r

e j j er

Ro

n s n s ds

n r r dl n s ds

i

j

j

A

B

2

1

1 12 1 13 1

12 2 23 2

2

1

exp ( ) ( ) .

. ( ) ( ) . exp ( ) )

v2

v.exp)v(.v

2v1

v

v).v()v,(ˆ 3

0

2

',

23

',', d

KT

m

KT

mT

e

eqq

e

e

bb

qqbeqq

0

1E-19

2E-19

3E-19

4E-19

5E-19

6E-19

7E-19

8E-19

9E-19

0 250 500 750 1000

Temperatura (eV)

eff (

m

Hg+ + e- --> Hg2+ + 2e- [46]

Cs+ + e- --> Cs2+ + 2e- [44]

Xe+ + e- --> Xe2+ + 2e- [45]

Cs2+ + e- --> Cs3+ + 2e- [44]

0.E+00

1.E-19

2.E-19

3.E-19

4.E-19

0 250 500 750 1000

Temperatura (eV)

eff (

m2)

Hg+ + e- --> Hg3+ + 3e- [48]

Xe+ + e- --> Xe3+ + 3e- [47]

Cs+ + e- --> Cs3+ + 3e- [44]

1 e 12

2

2

2m

poe

m

poe

r

rTT

r

rnn

Density and temperature profiles

dlyxTyxnIdlyxTyxnIII jjjj )),((ˆ),()),((ˆ),( 1311211

Primary beam attenuation

)),((ˆ),(2 12

22 yxTyxnI

dl

IdI j

jj

Secondary beam generation (dl is the projection of detector cell height into the primary beam path)

')),((ˆ),( 232

12

12

.)( dlyxTyxndIdIdI jjattj

Secondary beam attenuation (to integrate along secondary beam path dl’)

Espécie ne (m-3) Te (eV)

K+

(E=5 keV)~1019 (L=2 cm)

10 -1.310-4 210-3

Tl+

(E=100 keV)~1019

(L=30 cm)

1000 -0.410-4 0.810-3

21

2E

E

Plasma source (Cs+)

6.01072.1

2

27

23 d

a

V

mIP

Child-Langmuir perveance condition

in ISTTOK HIBD

sonda Langmuir

magnetefilamentode Ta

dispensadoresde césio

oríficio para extracçãodo feixe

electrodo filtro(-100 V)

electrodo de referência(0 V)

aneis de aquecimento

isoladores

Plasma source (Xe+/Hg+)

Detectorsecundário

Câmara

Plantaformasuperior do ISTTOK

Isolador

Válvula

Medidorde pressão

Pulsador

Fonte iónica

Isolador

Filtro demassa

Detector primário

Sistema dedeflecçãodo feixe

Isoladorcerâmico

Bomba Turbomolecular

FichasBNC

Célula deFaraday

Bomba turbomolecular

1122(det) )(ˆ)( 2 dsrrnABII jjeoj

Determination of

ˆ)(exp.)(ˆ)(.

.ˆ)(ˆ)(expI2I

223212

113112102

(det)

1

B

A

Rp

r ejje

r

RA

eej

j

j

i

dssndlrrn

dssnsn

Beam attenuation

Simplified

12en ̂

Simplified version

A1=0 (week primary beam attenuation due to tertiary ion production)

B=1 (weak secondary beam attenuation)

)(ˆ)(ˆ)( exp 2 11211212(det) dsrrn

I

dssnII jje

j

r

R eojj

i

dlI

Irn

j

jje

2

)(ˆ2(det)

12

The generation factor is related to the secondary currents by:

The current at the detector cell j is obtained by integration over the element dl obtained by the projection from the detector cell height length into the primary beam path.

1

0

2(det)2

10

j

LLj III

Cs+

Cs2+

detectorsecundário

detectorprimário

plasma

bobinestoroidais

a)

y

x

0

10

20

30

40

50

60

70

80

0 5 10 15 20

# cel

corr

ente

s (n

A)

Detector currents per row (linha)

Detector rows

0

1

2

3

4

5

6

-10 -5 0 5 10

raio (cm)

n x

(m

-1)

assumidorecuperado

0

0.2

0.4

0.6

0.8

1

1.2

-10 -5 0 5 10

raio (cm)

n x

(n

orm

aliz

ado)

assumidorecuperado

The beam attenuation in ISTTOK induces only first order effects to consider on the computation of the profile of

12en ̂

ne(0) = 11019 Te(0) = 200 eV Eb=22 keV I0=1 uA

Including the effect of attenuation on the secondary beams

A1=0 (week primary beam attenuation due to tertiary ion production)

B≠1 (moderate secondary beam attenuation (ISTTOK))

N

jjIII

1

2det0 2

1

The difference between injected primary beam current and detected primary beam current is equal to ½ of the all secondary beam current generated along the primary beam

N

jj

N

jjtotal IIIII

1

2(det)det0

1

3232 2

The total secondaries current lost by ionization to terciaries is given by the difference between the initial secondaries currents generated by the primary beam and the secondaries currents detected at the detector

32jIDetermination of the corrent lost by a single secondaries’ beam

Rp

rj ejjjjj dsnIIIII 23222

(det)232 ˆexp

1ˆ 23

p

j

R

r e dsn For ISTTOK

p

j

p

j

R

r ejR

r ejjj dsnIdsnIII 232

232232 ˆˆ1

Expanding the exponencial and taking only linear terms becomes:

N

j

pR

jr ej

pR

jr ej

total

jj

dlnI

dlnI

I

I

123

2

232

32

3232

ˆ

ˆ

So, one could find the fraction of each secondary beam current lost to terciary ionization by the ratio to the total lost current of all secondaries’ beams:

Rp

rj e dsn 23̂ Rp

rj e dln 12̂

Therefore

have similar shape to

Calculations show that:

Primary beam and secondary beams have similar radial trajectories in the plasma

Effective cross sections have similar shapes for I+I2+ and I2+I3+

0

0.5

1

1.5

2

2.5

0 0.05 0.1 0.15 0.2

percurso do feixe (m)

n x

(m

-1)

n x12

(normalizado)

Confirmed by calculations for several

ISTTOK plasma temperature and

density profiles

N

j

N

jLiiej

N

jLLLej

j

dlnI

dlnI

112

2(det)

122(det)

32

ˆ

ˆ

N

j

pR

jr ej

pR

jr ej

total

jj

dlnI

dlnI

I

I

123

2

232

32

3232

ˆ

ˆ

Experimentaly

determined

Replacing integrals by discret sums

A7

#cel = 7

dl para a célula 7

0

10

20

30

40

50

60

70

80

0 5 10 15 20

# cel

corr

ente

s (n

A)

77 7I A

I Acel celcel

# ##

0

0.5

1

1.5

2

2.5

3

3.5

4

0.79 1.28 1.31 1.28 1.25 1.23 1.21 1.19 1.16 1.15 1.12 1.11 1.08 1.08 1.06 1.03 1.09 0.54

dl (cm)

n x

m-1

)

Área sombreada = A7

A7 = LL

Le dln )ˆ(

18

712

N

jjjj IIII

1

2(det)det0

322 2

Absolute value of secondaries current at the ionization volume on the primary beam

0

1

2

3

4

5

6

-10 -5 0 5 10

raio (cm)

nex

12 (

m-1

)

recuperado

assumidoThe recovery of the absolute value of the generation factor is now more acurate

The remaining difference is due to ionization from primary to tertiary ions

Correction: see following slides

dln

I

dlnII e

j

r

R ejj

i1313120

3)31( ˆ)ˆˆ(exp3

Generation of tertiaries from the primary beam

(on the same volumes of generation of secondaries)

And the tertiaries generation factor can be given by

jj

jje

dlI

In

3

)ˆ(3

13

0.0

0.2

0.4

0.6

0.8

1.0

1.2

-10 -5 0 5 10

nx

(nor

mal

izad

o)

I + I +I 2 + I 3 +

raio (cm)

normenorme nn )ˆ()ˆ( 1213 We aproximate:

N

jej

ej

N

jj

jj

dlnI

dlnI

I

I

113

13

1

331

33131

ˆ3

ˆ3

N

jj

j

N

jej

ejj

I

I

dlnI

dlnI

1

2

2

112

1231

ˆ

ˆ

Using the aproximation

And obtain the tertiary currents at te ionization volume using:

33131331totaljj II

unknown

Experimentaly

determined

Estimation of the total current of the tertiaries: 3total

31 I

.3

2

3

22

331

1

2

1

331

te

total

totalN

jj

N

jj

CI

I

I

I

For a given temperature the ratio between production of secondaries and tertiaries is constant (only depends on the cross sections’ ratio)

In the plasma the temperature varies along the radius, but sensivity of the currents’ ratio to temperature profile changes is low

0.20

0.23

0.25

0.28

0.30

0.33

0.35

osc5

osc3 oc

o

pica

do

para

bolic

o

quad

rado

Fra

cçã

o d

e t

erc

iário

s R

100

200

300

Te(0) (eV)

(Curr

en

t ra

tio o

f te

rcia

ries

to

seco

ndari

es)

0

0.5

1

1.5

2

2.5

-10 -5 0 5 10

'assumido'

'recuperado'T e = 100 eV

n e = 5x1018 m -3

0

1

2

3

4

5

6

-10 -5 0 5 10

'assumido'

'recuperado'T e = 200 eV

n e = 1x1019 m -3

0

2

4

6

8

-10 -5 0 5 10

'assumido'

'recuperado'T e = 300 eVn e = 1.5x1019

m -3 0

2

4

6

8

-10 -5 0 5 10

'assumido'

'recuperado'

a)

b)

c)

Oco

a) Te = 100 eV e ne = 51018 m-3, b) Te = 200 eV e ne = 11019 m-3 e c) Te = 300 eV e ne =

1.51019 m-3.

Excellent recovery of absolute values of

12̂en

Example of effect of negleting atenuation factors

0

10

20

30

40

50

60

70

80

90

100

0 5 10 15 20

#linha

corr

ente

s (

nA

)

Detected currents

0

2

4

6

8

-10 -5 0 5 10

raio (cm)

n x

(m

-1)

assumidorecuperado

versão simplificada

0

2

4

6

8

-10 -5 0 5 10

raio (cm)

n x

(m

-1)

assumidorecuperado

versão intermédia

0

2

4

6

8

-10 -5 0 5 10

'assumido'

'recuperado'

a)

b)

c)

Osc5

Using full version of algorithm

A1=0

B=1

A1=0

B≠1 A1 ≠0

B≠1

Determination of electron density and electron temperature

)3,2(13

123

2

))((3

2

)ˆ(3

)ˆ(2PT

dl

dl

dlnI

dlnI

I

Ie

m

t

s

tPP

sPP

13

12)3,2( ˆ

ˆ)(

em T

Ratio between detected currents from 2 different ionization

processes on the same volume

Table of effective cross sections

In ISTTOK two ion species are used

)2,2(122

12)(2

112)(1

22

21 ))((

)ˆ(

)ˆ(PT

nI

nI

I

Ie

mm

Pm

pm

Pm

pm

m

m

-0.4 -0.3 -0.2 -0.1 0.1 0.2 0.3

-0.2

0.2

0.4

0.6

Hg+Hg3+ and Xe+Xe2+

(E = 22 keV, Hg = 32.0º, Xe = 33.3º).

0

4

8

12

50 100 150 200 250 300 350

temperatura (eV)

Ra

cio

s (a

bs.

)

Hg

Xe

12

12

ˆ

ˆ

(a)

Hg

Xe

13

12

ˆ

ˆ

(b)

-0.4 -0.3 -0.2 -0.1 0.1 0.2 0.3

-0.2

0.2

0.4

0.6

Xe+Xe2+, Xe+Xe3+ e Xe2+Xe3+

Hg+ Hg 2+, Hg+Hg3+ , Hg2+Hg3+

Hg+ Hg 2+, Hg+Hg3+ e Hg

2+Hg3+ Ip=6 kA.

-0.4 -0.3 -0.2 -0.1 0.1 0.2 0.3

-0.2

0.2

0.4

0.6

-40

-36

-32

-28

-24

-20

-5 0 5 10 15 20

z (mm)

y (

cm

)

Hg2+

Hg3+

iões Hg3+

provenientesda ionização dos iões Hg2+

coluna de célulasdo detector secundário

-0.4 -0.3 -0.2 -0.1 0.1 0.2 0.3

-0.2

0.2

0.4

0.6

0

25

50

75

100

-6 -4 -2 0 2 4 6

raio (cm)

corr

ente

s (n

A)

Xe 2+

Hg 3+

P 1P 2P 3P 4

50

90

130

170

210

0.00 0.02 0.04 0.06 0.08 0.10 0.12

percurso L (m)

tem

pera

tura

(eV

)

The two beams have overlaped trajectories

Detector currents

The Hg2+ currents are not detected, they can be estimated from the Xe2+ currents using the average

of the ionization ratio between the limits of temperature of ISTTOK (quasi constant function with

temperature)

)2,2(XeHg

22

1212

ˆˆ

XeHg

XeHg n

n

Therefore the generation of Hg2+ can now be estimated from

1

0

1

0

3(det)3

1120 )ˆ(

j

L

j

LLL

HgLj IdlnIII

And the Hg+ primary beam current at each ionization point given by

100

150

200

250

300

-6 -4 -2 0 2 4 6

Raio (cm)

Tem

pera

tura

(eV

) assumidos

recuperados

6.0

7.5

9.0

10.5

-6 -4 -2 0 2 4 6

Raio (cm)

De

nsi

da

de

(x1

018

m-3

)

b)

100

150

200

250

300

-6 -4 -2 0 2 4 6

Raio (cm)

Tem

pera

tura

(eV

) assumidos

recuperados

a)

6.0

7.5

9.0

10.5

-6 -4 -2 0 2 4 6

Raio (cm)

Den

sida

de (

x10

18 m

-3)

b)

50

100

150

200

250

300

350

-6 -4 -2 0 2 4 6

Raio (cm)

Tem

pera

tura

(eV

)

0

5

10

15

20

Den

sida

de (

x101

8 m

-3)densidade

temperatura

50

100

150

200

250

300

350

-6 -4 -2 0 2 4 6

Raio (cm)

Tem

pera

tura

(eV

)

0

5

10

15

20

Den

sida

de (

x10

18 m

-3)

densidade

temperatura

()TOF = TOF(t2) - TOF(t1) =

½(v0)-1{e{(ltr,t2) - (ltr,t1)}/E0} dltr + add Accounts for shifts on

trajectories due to external and internal

magnetic field changes

PULSER

SLIT

PLASMACHAMBER

BEAM POSITIONCONTROL

DETECTOR

Cs+ BEAM20 s

~250 ns

HI PASSFILTER

EARTHBREAK START

~6sDELAY

STOP TAC

FAST POWER SUPPLY

SHAPINGAMPLIFIER

FAST CHARGEPRE-AMP.

CONSTANTFRACTIONDISCRIM.

Distinguishing 2 ns delay

resolution (/)TOF ~310-4 for =7.2 s of time-of-flight of the beam pulse

from modulator to detector.

Plasma potential measurements using the primary beam

MCAD

Cs+

Stop Start

Modulator

Cs2+

Primary detector

Sample volumes Plasma

Average plasma potential

measurements

Absolute plasma potential measurements

Plasma potential measuremenst using the secondaries

K1F + eVF = K1P + eVP

K2P + 2eVP = K2D + 2eVD VP = (K2D - K1F) + (2VD - VF)

1

e

Energy conservation

x

y

zCh1

Ch2

Ch3

Ch4

MCAD

“Start” “Stop”Control module

Cylindrical plates

XY-alignment plates

Z-plates

620 mm

TOF-path module

Plasma Poloidal Field Measurements

Important: In ISTTOK all ion trajectories are very close to

radial

r

IB po

p 2

Poloidal magnetic field outside the plasma:

1

2)1(

2)1()1(21

211

2)1( 2

1

s

TaTvzzz pd

Primary beam initial

position

secondary beam increment from plasma bondary

to detector position

Velocity of primary beam at ionization

point X secondary time of flight

Secondary ions average

acceleration from ionization point

to plasma perifery

Secondary beam position

at cell (1)

dtT

TvdtTvzzzdv

j

jpjjjjjjdjj

21

)1(2

)(2

)(21

)1(2)()(2

)1(2

)1()1,(

dtdvdtvzz jjjjj

)1,()()()1( 2

1

)1,()()1( jjjj dvvv

dtdvTvTv jjjpjjpj

)1,()(

2)()1(

2)1( 2

2

1

2

1

2

1

Recursive calculation allows to determine the accelerations at ionization point

vdt

dv

e

mBp

1poloidal field module can

be obtained from

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

-10 -5 0 5 10

raio (cm)

j (

MA

/m2 )

j plano

j parabolóico

j picado

-31

-28

-25

-22

-5.5 -5.1 -4.7 -4.3 -3.9 -3.5 -3.1 -2.7

z (mm)

y (c

m)

plano

parabolóico picado

0

5

10

15

20

25

30

-10 -5 0 5 10

raio (cm)

Bp

(mT

)

o B p+ recuperado B p+ assumido - B p totalj picado

j parabolóico

j plano

0.0

0.1

0.2

0.3

0.4

0.5

0.6

-10 -5 0 5 10

raio (cm)

j (

MA

/m2 )

oco

0

5

10

15

20

25

-10 -5 0 5 10

Raio (cm)

Bp

(mT

)

o B p+ recuperado B p+ assumido - B p total

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

-10 -5 0 5 10

raio (cm)

j (

MA

/m2 )

perturbaçãolocalizada

0

5

10

15

20

25

-10 -5 0 5 10

Raio (cm)

Bp (

mT

)

o B p+ recuperado B p+ assumido - B p total

-31

-28

-25

-22

-5.3 -4.9 -4.5 -4.1 -3.7 -3.3

z (mm)

y (

cm)perturbaçãomagnética

parabolóico

DETECTOR RESOLUTION (mm)

Border Center

A 0.3 0.2

C 0.6 0.3

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

-10 -5 0 5 10

raio (cm)

j ( M

A/m

2 )

pedestral

-31

-28

-25

-22

-5.5 -5.1 -4.7 -4.3 -3.9 -3.5 -3.1

z (mm)

y (c

m) pedestral

parabolóico

0

5

10

15

20

25

30

-10 -5 0 5 10

Raio (cm)

Bp

(mT

)

o B p+ recuperado B p+ assumido - B p total

0.0

0.2

0.4

0.6

0.8

1.0

1.2

-10 -5 0 5 10

raio (cm)

j (M

A/m

2 )assimétrico

-31

-28

-25

-22

-5.5 -5.1 -4.7 -4.3 -3.9 -3.5 -3.1 -2.7

z (mm)

y (

cm)

picado

assimétrico

0

5

10

15

20

25

30

-10 -5 0 5 10

Raio (cm)

Bp (

mT

)

o B p+ recuperado B p+ assumido - B p total

EXPERIMENTAL RESULTS

4.5

1.4

-1.6

-4.4

3.55

.57.59

.511.513.515.517.519.521.523.525.527.529.5

0

1

2

3

4

5

ne

(m

-1)

4.5

2.4

0.4

-1.6

-3.5

3.5

5.5

7.5

9.5

11.5

13.5

15.5

17.5

19.5

21.5

23.5

25.5

27.5

29.5

raio (cm)

tem

po

(m

s)

Plasma current

Average density - comparison with interferometer

00.2

0.40.60.8

11.2

3 6 9 12 15 18 21 24 27 30

tempo (ms)

u. a

.

HIBD

Beam off

12̂en

4.7

-2.4

1622

2834

4046

5258

32.8

0

0.01

0.02

0.03

0.04

0.05

ne

x

(u

.a.)

4.7

1.1

-2.4

13

16

19

22

25

28

31

34

37

40

43

46

49

52

55

58

61

raio (cm)

tem

po (m

s)

12̂en

Te , ne

Plasma current for 2 discharges Radial average density for two discharges

-20

213

19

25

31

0

70

140

210

T e (

eV)

R (cm)

t (ms)

-20

213

19

25

31

4

6

8

10

12

ne

(10

18 m

-3)

R (cm)

t (ms)

interferometer

HIBD

The change in average

plasma potential is -450 V,

Vp

0

1000

2000

3000

4000

5000

6000

7000

8000

0.00 10.00 20.00 30.00

TIME (ms)

P L A

S M

A C

U R

R E

N T

( A

)

#2939

#2940

T1 T2 T3 T4

Bp

1.2

1.6

2.0

2.4

2.8

3 4 5 6 7

Row Number

( y

) ( m

m )

T

T

T

T

-1

0

1

2

3 4 5 6 7

Row Number

P o l o

i d a l F

i e l d

N o r m

a l i s

e d t o P

l a s m

a

C

u r r

e n t (

a . u

. )

T

T

T

T

A1 A2

A3

A4

1

2

3

4

references

33. ”Time–of-flight energy analyser for the plasma potential measurements by a heavy ion beam diagnostic”S. Nedzelskiy, A. Malaquias, B. Gonçalves, C. Silva, C. A. F. Varandas, and J. A. C. Cabral,REVIEW OF SCIENTIFIC INSTRUMENTS VOLUME 75, NUMBER 10 OCTOBER 2004, pp. 3514-3516in Proceedings of 15th Topical Conference High-Temperature Plasma Diagnostics, San Diego, California, April 19-22,2004

1."Developement of a new type of Cs Plasma Ion Gun for application in a heavy ion beam tokamak diagnostic" J.A.C. Cabral, O.J. Hancock, A.J.T. Holmes, M. Inman, C.M.D. Mahony, A. Malaquias, A. Praxedes, W. van Toledo and C.A.F. Varandas. Plasma Sources Science and Technology, 3, 1994, pp. 1-9.

2."The Heavy Ion Beam Diagnostic for the Tokamak ISTTOK" J.A.C. Cabral, A. Malaquias, A. Praxedes, W. van Toledo, and C.A.F. Varandas. IEEE Transations on Plasma Science, vol 22 nº4, August 1994.

3."The Control and Data Acquisition System for the ISTTOK Heavy Ion Beam Diagnostic" C.A.F. Varandas, A.J. Baptista, C. Coreia, A. Malaquias, J. C. Mata, A Praxedes, A. P. Rodrigues, J. Sousa, W. Toledo and J.A.C. Cabral Meas. Sci. Technol. 6 (1995) 1588-1597.

5."Analysis of the ISTTOK plasma density profile evolution in sawtooth discharges by heavy-ion beam probing" J.A.C. Cabral, C.A.F. Varandas, A. Malaquias , A. Praxedes, M. P. Alonso, P. Belo, R. Canário, H. Fernandes, J. Ferreira, C. J. Freitas, R. Gomes, J. Pires, C. Silva, A. Soares, J. Sousa and P.H.M. Vassen Plasma Phys. Control. Fusion 38 (1996) 51-70

6.“Engineering Aspects of an Advanced Heavy Ion Beam Diagnostic for the TJ-II Stellarator” A. Malaquias, C. Varandas, J.A.C. Cabral, L.I. Krupnik, S.M. Khrebtov, I.S. Nedzelskij, Yu. V. Trofimenko, A. Melnikov, C. Hidalgo, I. Garcia-Cortes Fusion Technology V.1 pp. 869, 1996

8."Evolution of the poloidal magnetic field profile of the ISTTOK plasma by heavy ion beam probing" A. Malaquias, J. A. C. Cabral, C.A.F. Varandas and R. Canário Fusion Engineering and Design, 34-35 (1997) 671-674

10.“Evolution of the tokamak ISTTOK plasma density and electron temperature radial profiles determined by heavy ion beam probing” A. Malaquias, I.S. Nedzelskii, C.A.F. Varandas, and J.A.C. Cabral Review of Scientific Instruments, V70, N1, Jan 1999, Part II. Pp. 947-950