Ideas for “overseas” Ideas for “overseas” contributions to CMSOcontributions to CMSO

Piero MartinPiero Martin

Consorzio RFX Consorzio RFX Associazione Euratom-ENEA sulla fusioneAssociazione Euratom-ENEA sulla fusioneAnd Physics Dept., Univ. of Padova, ItalyAnd Physics Dept., Univ. of Padova, Italy

CMSO General Meeting CMSO General Meeting Madison, WI – Aug. 6-8, 2004Madison, WI – Aug. 6-8, 2004

With contributions from RFX, MST, EXTRAP T2R and TPE-RX groupsWith contributions from RFX, MST, EXTRAP T2R and TPE-RX groups

The new RFX deviceThe new RFX device

Main new components:Main new components:

1.1. 192 saddle coils, covering the whole plasma boundary, each 192 saddle coils, covering the whole plasma boundary, each independently powered and feedback controlledindependently powered and feedback controlled

2.2. a smoother and thinner shella smoother and thinner shell

3.3. the first wall with higher power handling capabilitiesthe first wall with higher power handling capabilities

4.4. an in-vessel system of magnetic and electrostatic probesan in-vessel system of magnetic and electrostatic probes

5.5. the toroidal field power supplythe toroidal field power supply

R R //aa = 2.0 / 0.46 (m) - = 2.0 / 0.46 (m) - II up to 2 MA up to 2 MA

Overview of the magnetic boundaryOverview of the magnetic boundary

- 4 coils in the poloidal direction: 90° spaced– 48 coils in the toroidal direction: 7.5° spaced

shellshellvessevessell

Active Active saddle saddle coilscoils

Saddle coil performanceSaddle coil performance

each independently powered24 kAt: 400 A x 60 turns

Wide spectrum of Fourier Wide spectrum of Fourier components can be components can be produced:produced:

•m=1,2•n ≤ 24•DC < f < 100 Hz

Significant amplitude available. For example: edge br for (1,8) mode:

• 20 mT@10 Hz• 1.3 mT @100 Hz

Magnetic probeMagnetic probe

•97 Electrostatic (Langmuir) probes•139 Magnetic pick up probes •8 Calorimetric probes

Langmuir probeLangmuir probe

Integrated System of the Internal Sensors Integrated System of the Internal Sensors (ISIS)(ISIS)

RFX and CMSO activitiesRFX and CMSO activities

Active feedback controlActive feedback control of magnetic of magnetic turbulence in a laboratory plasma device with turbulence in a laboratory plasma device with FULL COVERAGEFULL COVERAGE of the plasma surface. of the plasma surface.

Selective depression/excitation of selected MHD Selective depression/excitation of selected MHD instabilitiesinstabilities

Dynamo studiesDynamo studies Resistive Wall Modes controlResistive Wall Modes control Magnetic turbulence controlMagnetic turbulence control ……………………

… … together with strong plasma diagnostic together with strong plasma diagnostic capabilitiescapabilities!!

The Single Helicity (SH) dynamoThe Single Helicity (SH) dynamo

a theoretically predicted state with a unique a theoretically predicted state with a unique m m = 1 saturated resistive = 1 saturated resistive kink (kink (a pure helix wound on a torusa pure helix wound on a torus), ),

Stationary Stationary LAMINARLAMINAR dynamo mechanism with good helical flux surfaces dynamo mechanism with good helical flux surfaces

MAC-302MAC-302

Escande, Martin et al., PRL 85 Escande, Martin et al., PRL 85 (2000)(2000)

Dynamo electric field in QSHDynamo electric field in QSH

Dynamo in QSH becomes more concentrated in Dynamo in QSH becomes more concentrated in one mode than in standard MH plasmas!one mode than in standard MH plasmas!

)~~( bv

Piovesan, Craig, Marrelli, Martin, submitted to PRL

QSH coherent structureQSH coherent structure

Remember we can apply with the saddle coils up to ~20 mT

on a single m=1 mode

10-9

10-8

10-7

10-6

10-5

0.0001

0.001

0.5 1 1.5 2 2.5

eps42wf3_4/f5_10

Wr( 0, 1)Wr( 0, 2)Wr( 1, 1)Wr( 1, 2)Wr( 1, 3)Wr( 1, 4)Wr( 1, 5)Wr( 1, -1)Wr( 1, -2)Wr( 1, -3)Wr( 1, -4)Wr( 1, -5)Wr( 1, -6)Wr( 1, -7)Wr( 1, -8)Wr( 1, -9)Wr( 1,-10)Wr( 1,-11)Wr( 1,-12)Wr( 1,-13)

Time

Numerical studies on active control: successful drive and sustainment of m=1 n=7 SH state starting from MH

conditions

•Low dissipation Low dissipation conditionsconditions

•Thin shellThin shell

•Simoultaneous Simoultaneous active control of active control of RWMs !RWMs !

Paccagnella, MHD workshop 2002

Preliminary experiments in the EXTRAP T2R Preliminary experiments in the EXTRAP T2R RFPRFP

RFX equipment tested in the EU EXTRAP T2R device at KTH in StockholmRFX equipment tested in the EU EXTRAP T2R device at KTH in Stockholm QSH spectra excited in a high aspect ratio device!QSH spectra excited in a high aspect ratio device! More experiments underwayMore experiments underway

Test particle transport studies: Test particle transport studies: magnetic stochasticity vs. ordermagnetic stochasticity vs. order

SHSH QSHQSH MHMH

Numerical simulation predicts better confinement in SHNumerical simulation predicts better confinement in SH

With the ORBIT code a set of test particles is deposited in the With the ORBIT code a set of test particles is deposited in the plasma core in plasma core in MH/QSH/SHMH/QSH/SH and followed in their outward motion. and followed in their outward motion.

Particle loss time estimated; confinement Particle loss time estimated; confinement SH > QSH > MHSH > QSH > MH

Poloidal anglePoloidal angle Predebon et al, submitted to PRL

Upgraded soft x-ray tomography for Upgraded soft x-ray tomography for MSTMST

Two more fans added: total 4Two more fans added: total 4

Franz et al., RSI 2004

Imaging of individual small islands in the Imaging of individual small islands in the plasma coreplasma core

SXR imageSXR image

Numerical reconstruction of Numerical reconstruction of magnetic field linesmagnetic field lines

Franz et al., PR:L 2004