7th IOS-ITPA, Kyoto, April 18th-22th 2011 A.A. Tuccillo

FTU ActivityA. A. Tuccillo on behalf of FTU Team

Since last ITPA in Culham• Main Experimental Programme ended in May due to:

– Explosion of two secondary breakers (20kV) on LH– Failure of McPherson UV spectrometer 150kV

failure?– Short circuit on Electro-Optic Probe (dust detection)

• Experimental Programme continued till July, to:– Commissioning new front mirrors RT steerable ECRH La

uncher– Some ECRH and OH exps on

density limit (recycling, Li/B/Mo)– Some diagnostic commissioning

• Summer Shutdown:– ECRH antenna inspected, refurbished and reinstalled– LH fully refurbished, new 12 arm power divider

commissioning– Mc Pherson 2 Heads repaired, under calibration (by Oct

on FTU)– Electro-Optic Probe refurbished and reinstalled

FTU pumping down started lst week Friday 14th:

7th IOS-ITPA, Kyoto, April 18th-22th 2011 A.A. Tuccillo

RT EC Antenna:Test of Poloidal Movement /1

Deg

Deg

Deg

/sD

eg/s

Poloidal

Toroidal

Time (s)

#34888 αPol 28°14°, βTor=0°Max δα= -0.305°Max δβ= 0.056°Max Va= -45.7°/sMax Vβ= 8.5°/s

Time (s)

Δα (D

eg)

Acceptable low error on poloidal angle: accounting for beam waist

7th IOS-ITPA, Kyoto, April 18th-22th 2011 A.A. Tuccillo

Summary of progress• New ECRH launcher for ST/(N)TM real time control installed in FTU in

spring 2011 2 steerable mirrors symmetric to eq. plane: αPol=±25°(ρ=±0.7)/βTor=±40° steering velocity: 1° (1cm)/10ms • Technical test w and w/o plasma completed:characterization of launched beam in vessel

with low power (mW) source validation of power handling EC power deposition location

• RT control sys. under development

completed: preliminary version of RT DAS:

8 diagnostics chs + 2 ECRH, 20 kHz) real time data elaboration:

ECE/ECRH/Mirnov cross correlation power deposition location

pre-prog sweepingα=-28° α=-14°

RT EC Antenna:Test of Poloidal Movement /2

7th IOS-ITPA, Kyoto, April 18th-22th 2011 A.A. Tuccillo

ITPA: EC Assisted Breakdown on FTU

G. Granucci et al. Nucl. Fusion 51 (2011) 073042

Resonance scan evidence and perspectives: Reduced flux consumptionFaster current ramp (outer localization)Control of plasma starting point

li

I P (kA

)

Te (

keV

)R (m)

7th IOS-ITPA, Kyoto, April 18th-22th 2011 A.A. Tuccillo

Next planned experiments1. FTU can reproduce same Vloop evolution

foreseen in ITER, this will be exploited in:– studying the O1 vs X2– exploring minimum electric field in both scenarios

2. Steering beam to study the effect of EC deposition vs. null position

3. Upper or equatorial injection with/without toroidal angle . Exploiting the new fast steerable launcher

4. Exploitation of new fast visible camera for plasma evolution measurement (formation, drift, extension)

7th IOS-ITPA, Kyoto, April 18th-22th 2011 A.A. Tuccillo

ST destabilization by modulated ECH/ECCD /1

Aim:• pulsed ECH used as trigger of ST crashes to test conditions for a-priori constant ST in view of the real time control of ST period Experiment:• 3 constant ECH modulations (for 500ms):

• 20Hz (20% and 80% duty), 125Hz (50%)• target plasma:

Ip=500kA, 5.1T<Bt<5.9T, ne=0.6 1020m-3

EC rdep moves from inside to outside q=1• ECE 12-channels polychromator for Te profiles, ST crashes and q=1 position (inversion radius)

10ms on/40ms off

First Answers: 0.8 MW of EC power (Pohm=0.5MW) inside q=1 shortens ohmic ST = 6.4ms

up to ~ 35% (ECH only) and ~ 45% (coECCD) magnetic shear s1 at q=1 increases up to 0.3 at ST crash where s1 > scr

ST amplitude exhibits a maximum ~ 1.7 its ohmic value

40ms on/10ms off

4ms on/4ms off

Btor scan

Te

Te

Te

#33257

#34285

#34286

q=1inside outside

7th IOS-ITPA, Kyoto, April 18th-22th 2011 A.A. Tuccillo

ST (de)stabilization by modulated ECH/ECCD /2

q=1 q=1

inside q=1outside q=1

inside q=1

outside q=1

ohmicohmic

Pure EC heating coECCD

q=1

ohmic

The observed stabilizing effect of fast EC modulation in central region inside q=1 with phase on > ohmic suggests to use faster modulation (1KHz/500Hz @50%) to reduce ST

Transport calculations are in progress to simulate and predict this

behaviour New real time ECRH launcher will allow soon to keep constant ST by

proper EC beam steering (0.3 < rdep / r1< 0.6) and compare results with those

of other machines (TCV, ASDEX, TS… ?)

stab. ST

20Hz @ 80% 20Hz @ 20%125Hz @ 50%

**

*

inside q=1

outside q=1

7th IOS-ITPA, Kyoto, April 18th-22th 2011 A.A. Tuccillo

IP: 900 kA, 700 kA, 500 kA discharges with increasing density up to disruption

Hugill plots of the FTU discharges:

(a) Central line average densities (r/a = 0)(b) External line average densities (r/a = 3/4)

Open symbols: Onset of the MARFESolid symbols: Disruption for density limit

The central and the external line average densities corresponding to the onset of the MARFE are linear functions of the average plasma current density.

The maximum achievable central line average density is not scaling linearly with the average plasma current density: the Greenwald limit is exceeded for qcyl > 4 (q > 5), while it is not reached for qcyl < 4.

The external line average density at the disruption for density limit results to scale as a fraction of the Greenwald limit.

Looking for Density limit on Toroidal field in FTU

7th IOS-ITPA, Kyoto, April 18th-22th 2011 A.A. Tuccillo

After the onset of the MARFE, with increasing density there is a strong peaking of the density profiles which.

The reduced temperature at the edge make the plasma more transparent to the neutrals and determine an increase of the particle source inside r/a = 3/4.

The dependence of the density peaking on the edge safety factor play a crucial role on the determination of a density scaling law when the central line average density is considered.

The combination of the external Greenwald limit and the q-dependent density peaking results in a more then linear dependence of the maximum achievable central line average density on the toroidal magnetic field and a substantial independence on the average plasma current density.

Looking for Density limit on Toroidal field in FTU /2

7th IOS-ITPA, Kyoto, April 18th-22th 2011 A.A. Tuccillo

Fast Camera

In the frame of EFDA MHD Tasks on Disruption characterisation and dust dynamics a fast camera has been commissioned on FTU at the end of 2010

3600 frames/s at full resolution Up to 500000 frames/sec at reduced resolutionCollection optics through fiber bundle

7th IOS-ITPA, Kyoto, April 18th-22th 2011 A.A. Tuccillo

Fast Camera MARFE oscillation Dust

7th IOS-ITPA, Kyoto, April 18th-22th 2011 A.A. Tuccillo

Read out pads

(pixel size6×12 mm2)

9000counts

2000counts

9000 counts

Collaboration ENEA-INFN-CEA (EFDA WP10-DIA-04-03)Gas Electron Multiplier “GEM”: Evaluation of Immunity to Neutron Irradiation

10cm

10cm

16 pixels

8 pi

xels

Frascati Neutron Generator

deuterated target 2.5MeV

GEM detector in front of the

neutron D-D target

o Neutrons contribution is spatially uniform

o Fe55 signal has a well-defined spatial shape

o Background Correction will be active based on pulse shape

Neutrons and γ contribution to

theExperimental set

up

7500 counts 9000 counts

2000counts

Only X-rays (Fe55) X-rays and neutron

Neutron Flux=2.1 106n/s

7th IOS-ITPA, Kyoto, April 18th-22th 2011 A.A. Tuccillo

7500 counts

9000counts

9000 counts

Collaboration ENEA-INFN-CEA (EFDA WP10-DIA-04-03)Preliminary tests on polycapillaries as SXR lenses for MCF diagnostics

SXR radiography of the mesh (holes 400

mm) SXR image of the mesh with

fulllens (magnification ~6 )

Full lens: produces a divergent beam, with an image magnification, and spot broadening is linear with the distance (also much larger than the focal distance)

Half lens: is an excellent light collector, very low divergence (quasi-parallel output beam even at large distance)

Imaging: the geometry of the sample is perfectly reproduced without any distortion

Full lens

Half lens

7th IOS-ITPA, Kyoto, April 18th-22th 2011 A.A. Tuccillo

FTU programme 2011-12Experimental Campaigns in 2011:

1. March 14th – July 1st • Successful Plasma Restart March 15th – March

27th • Programme Ops started April 5th

2. November 2nd – December 10th Experimental Campaigns in 2012:

3. January 31st – March 30th 4. May - June (to be decided)

All systems operative, but:– ECRH 3 gyrotrons available, but 2 magnets being

fixed in November, 4th gyrotron back from Russia end of November

– ECRH Power switchable between two antennas: Old and RT,

– LHCD 5 lines available

7th IOS-ITPA, Kyoto, April 18th-22th 2011 A.A. Tuccillo

2011-12 FTU programmeResponsible for the programme till next IAEA

FEC P. Buratti• Tearing mode control• Sawtooth control • Disruption avoidance (LH fast e-) with new RT EC

Antenna• Assisted breakdown (Fast Camera)• OXB heating

• LHCD at high plasma density (complete scan at higher Power

(IOS 5.3) control externa Te by ECRH)

• Control of metallic impurities (W-Mo) by impurity seeding

• Study low W ionisation states• High power operation with Liquid-Lithium-Limiter