george sips itpa, active control, 14 july 20031 real-time control ( and development of control...

George Sips ITPA, active control, 14 July 2003 1

Real-time Control

(and development of control systems)

at ASDEX Upgrade

George Sips

Max-Planck-Institut für Plasmaphysik, Boltzmannstrasse 2, D-85748, Garching,Germany.


Covers many physics areas,

and various different diagnostic input data in real time.

Areas for plasma control (development) at ASDEX Upgrade

• Control of plasma performance: (density profile, regime identification).

• Control of MHD instabilities: (NTM´s, sawteeth, ELM´s, ELM type).

• Control of q-profile, with on-line q(r) identification.

• Other control schemes including plasma protection.


Actuators at ASDEX Upgrade


Off axis heating: Peaking of density profile, but MHD unstable (NTM’s).

Use of central ICRH or ECRH: Can control the density peaking.

Control of density profile

AIM: Density profile control, also including the heating power as actuator


Control of High Z impurities in the core

Improved H-mode: NBI: 5 MW (2.5 MW off axis), ECRH, no sawteeth.

With ECRH: Density peaking reduced, no accumulation of Tungsten.


Regime identification

If you would like to know if the

discharge is in L-mode or H-mode.

Important for other control

schemes: Density feedback,

plasma protection, divertor.

Use of power threshold scaling law

is not sufficient at all.

H-mode or L-mode



Construct training data set >

3000 observations (by hand).

Identify:

H-mode or L-mode.

Improved H-mode or not.

Store for each data point 0-D

diagnostic data.

Automated search using

discriminant analysis on best

variables to use and optimimum

number of variables.

H-mode or L-mode dataset.



H-mode or L-mode.

Variables used for

identification

Ploss,q95,p,Ip,Vloop

Similar good results for

Improved H-mode or NotProbability x100%


3/2 NTM stabilisation

• More ECRH power, new mirror system for launch angle control.

• NTM detection algorithm using real time Te(r) data


Sawteeth control with ECCD

CounterECCD, 0.7 MW

#15847H-mode with 5 MW NBI

Sawteeth stabilisation (A. Mück):

• Counter ECCD, inside q=1 surface.

• Co ECCD, just outside q=1 surface.

• ECCD deposition tuned with B-field.

ECR deposition in pol.

-0.4 -0.2 0.0 0.2 0.4

4

0

6

2 ST/( S

T_n

o_E

CR)

New gyrotrons and mirror system

for 2003/2004

Co-ECCD


q95 = 3.6, sep.= 0.43, N=3.5

q95 = 3.7, sep.= 0.44, N=3.2

q95 = 4.4, sep.= 0.34, N=2.2

q95 = 3.3, sep.= 0.17, N=3.0

Control of ELM behaviour: plasma shape


x of the seperatrices at the outer midplane

0.5

0.4

0.3

0.2

0.1

<>

-0.06 -0.04 -0.02 0.00

x

0.2 - 0.4 ne/nGW

0.4 - 0.6 ne/nGW

0.6 - 0.8 ne/nGW

> 0.8 ne/nGW

• q95 > 3.5, pure Type II ELM´s possible.

• 0.85 < ne/nGW < 0.95.

• Close to double null shape. Type II

Control of ELM type: Type II ELM´s access conditions


Controlled external ELM triggering

Small pellets at 20 Hz are used to trigger ELM´s (P. Lang)

Pellet trigged ELM is similar to natural ELM.

IF E can be maintained, WELM/Wmhd can be reduced when fpellet > fnatural-ELM

A. HerrmannPSI 2002 ?


2 NBI sources (#6, #7) at NI-2 are off-axis,

tangential injection at 93kV, Deuterium Higher current drive efficiency With other NB sources: Control of power/particle deposition

NBI system at ASDEX Upgrade :

Motivation for current profile control at ASDEX Upgrade


NBI - power, source MIMO system :

)(rj

MSE, Magnetic Probe Measurements

ControllerAdaptive

PID

Statistical Methods

j (r), q (r)

magnetic pitch angle data

NBI

FP

ECCD

Current profile control at ASDEX Upgrade


0.0 0.2 0.4 0.6 0.8 1.0

0.0

0.5

1.0

1.5

NBI5 NBI6 NBI7 NBI8

Cu

rren

t D

ensi

ty (

MA

/m2 )

tor

total j j

NB

jBSK

0.0 0.2 0.4 0.6 0.8 1.00

2

4

6

8

10

12

Saf

ety

Fac

tor

q

tor

NBI5 NBI6 NBI7 NBI8

0.0 0.2 0.4 0.6 0.8 1.00

1

2

3

4

Ele

ctro

n T

emp

erat

ure

(ke

V)

tor

NBI5 NBI6 NBI7 NBI8

0.0 0.2 0.4 0.6 0.8 1.00

1

2

3

4

Ion

Tem

per

atu

re (

keV

)

tor

NBI5 NBI6 NBI7 NBI8

ASTRA Simulations of 4 different NBI sources


#17530

MSE signal : exp .VS. ASTRA

1 2 3 4 5 6 70.0

0.1

0.2

0.3

0.4S

tore

d E

ner

gy

(M

W)

Time (sec)

Exp. ASTRA with j

NB

ASTRA w/o jNB

0

5

10

15

20

PNB

(MW)

3 (MSE)

8 6 5 7 8

1 2 3 4 5 6 70

2

4

6

8

MS

E A

ng

le (

deg

)

Time (sec)

1 2 3 4 5 6 72

3

4

5

6

Channel 6 with jNB

Channel 6 w/o jNB

Channel 5 with jNB

Channel 5 w/o jNB

MS

E A

ng

le (

deg

)

Time (sec)

Astra Simulation vs Experiment at 400 kA

Different NBI sources:


2 4 6 8 10

Neutral beam power modulated

for optimum response on current

diffusion time scale(MW) NBIP

Time (s)

Modulated NBI

5

10

0.0 0.2 0.4 0.6 0.8 1.00.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

Cu

rren

t D

ensi

ty (

MA

/ m

2 )

r / a

ASDEX Upgrade

0.0 0.2 0.4 0.6 0.8 1.00.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

Cu

rren

t D

ensi

ty (

MA

/ m

2 )

r / a

ASDEX Upgrade

ASTRA Simulations of modulated NBI sources

These simulations are used to identify the system response function


7 8 9 100

5

10

PN

BI

(MW

)

Time (sec)

0.0 0.1 0.2 0.3 0.4 0.5 0.620

40

60

80

100

Test

Training

NBI5 NBI6 NBI7 NBI8

Acc

ura

cy (

%)

Minor Radius

pol

Source6 - poloidal beta

98.1 %

55.6 %

Source8 - j(0.225)

best

result

worst

result

System identification and validation with step response


Otrher control schemes

• Control of several neutral particle flux densities via D gas injection.

• Choice of several different line densities control via D gas injection.

(including edge density and possibility to switch during the pulse).

• Control of these line densites with pellet injection.

• Control of Tdiv (thermoelectric currents), or control of Pdiv via

impurity gas injection.

• Control of isotope mix H/(H+D).

• Reduction of Halo currents.

• Pulse repair from Deep Detachment.


Control of H/(H+D) mixure and line average density


O: Without Killer pellet.: With mode-lock detector.X: With Killer pellet.

Killer pellet activated with Neural net, trained to predict time to disruption.

But network ages rapidly, to give < 80% reliability.

Reduction of Halo current during disruptions


Deep detachment repair vs. Termination with killer pellet

Repair,

But experiment

compromised ?

Termination,

Experiment finished

Machine safe.


Design of new digital control system (ready 2003)

Termination,

Experiment finished

Machine safe.

Present system (own design): Transputer network, ~ 2 - 5 ms

New system (commercial): Shared memory netw. ~ 1 ms


Conclusions

Major new real time control schemes are being developed for ASDEX

Upgrade: Density profile control, Regime identification, NTM and sawtooth

stabilisation, ELM control and current profile control.

Together with existing control scheme and real time diagnostic

measurements form a consistent set of control tools.

New real time control hardware is being installed and should be ready for

commissioning in 2003

george sips itpa, active control, 14 july 20031 real-time control ( and development of control...

Documents

active control

control of q

sawteeth control

control schemes

realtime control

density profile control

mode slide

george sips itpa