ECRH assisted Studies using Ordinary and Extra- Ordinary Mode on GLAST III

RiazRiaz KhanKhan,, M.M. NazirNazir,, A.A. Ali,Ali, S.S. HussainHussain,, A.A. QayyumQayyum,, Z.Z. Ahmad,Ahmad, A.A. NaveedNaveed,, S.S. Ahmad,Ahmad, && R.R. AliAli

National Fusion Program, PAEC PAKISTAN

23rd IAEA TM on the Research Using Small Fusion Devices, 29-31 March 2017, Santiago, CHILE 1 Outline of Talk

• Introduction to GLAST Series ?

• Pre-ionization Source for GLAST III

• Ordinary & Extra-Ordinary Mode Study

• Plasma Current Studies on GLAST III

• Future Goals

2 First Tokamak (GLAST-1) (NTFP, 2011-13)

Diagnostic systems Steel pipe at center Power supply systems Chamber dia = 50 cm Aspect ratio = 1.5 21/39 First Plasma Shot on GLAST assisted pre-ionization in Neon gas

22/39 Second Tokamak (GLAST-2) (NTFP, 2013-14)

Glass tube at center Chamber dia = 50 cm Diagnostic systems Power supply systems Aspect ratio = 1.6 23/39 Best Plasma Shot on GLAST-2

Plasma Current = 5 kA

24/39 Temporal Formation of Plasma in GLAST (5000fps-----1 frame = 0.2 msec) Third Tokamak (GLAST-3) (NTFP, 2014-till to date)

Chamber diameter = 60 cm Diagnostic Aspect ratio = 2 Power supply systems systems

25/39 Diagnostics Installed on GLAST III

Voltage loop, Differential loop, Poloidal and toroidal loops, Rogowski Coil, Photodiode,Tripple Langmuir Probe, Spectrometer HR 4000, HR 2000+ Monocrometer,High Speed Camera, X-ray detector, Line of sight arrangement (special and temporal for H-alpha emission), Emissive probe (under construction),RGA (Residual Gas Analyzer), RF Spectrum Analyzer, and Power Meter. Best Plasma Shot on GLAST-3

May 2015 Plasma Current = 8kA

26/39 Pre-ionization Sources for GLAST

• In GLAST, are utilized for ECRH assisted startup. This technique reduces ohmic flux requirement for startup purpose . •

• Domestic microwave oven magnetron operates at about -4.1kV applied to the cathode. • Transformer with High voltage winding (220V Æ2.2kV) and Low voltage winding (3.5V, 11A) for filament current is used along with a voltage doubler circuit to meet this requirement. • With 50Hz operating frequency, the observed waveform has 10msec on-time and 10msec off-time Pre-ionization Sources for GLAST • 800W Half Wave Rectification Source

With 50Hz operating frequency, the observed waveform has 10msec on- time and 10msec off-time. • 800W Full Wave Rectification Source

Two voltage doubler circuits are used for achieving full wave rectification.

10msec off-time of HWR circuit is also included in on-time of magnetron. Pre-ionization Sources for GLAST • 800W Pulsed RF source • In order to synchronize the launched RF with the Toroidal pulse, a pulsed source is developed. • Electrical pulse provided through a charged capacitor operates the magnetron in pulsed mode. • Pulse of duration 8msec has been achieved. • 1600W Pulsed RF Source • An extra magnetic field is generated using a coil wrapped in between permanent magnets with its own power supply to confine escaping electrons which results in doubling the output power. GLAST Pre-ionization System

Pre-ionization Study using Different Polarization

• Toroidal Field • Microwave 2.45 GHz (WR-340 Wave Guide) • With and Without Central Solenoid Diagnostics • Langmuir Probe • Photo Diode • RF Diode • Spectrometer • Rogowski Coil • Gas:

TE1,0 mode propagating through a waveguide Toroidal Field Profile of GLAST III

1000

875 G at 12cm 800

600

400

Toroidal Field (Gauss) Toroidal 200

0 10 15 20 25 30 35 Distance (cm) O mode Discharge (E parallel to BT)

40-7 μ bar 8 Ref MW 2x10-02 mbar 6 9x10-03 mbar 7x10-03 mbar TF Current

4 7 1-0.5 μ bar 1x10-03 mbar 2 6 9x10-04 mbar 7x10-04 mbar Microwave Detector Output Detector Microwave 5 0 5x10-04 mbar TF Current -0.002 0.000 0.002 0.004 0.006 0.008 0.010 4 Time (msec) 3

2 7 5-3 μ bar 6 1 5x10-03 mbar Power Deteced Microwave 5 3x10-03 mbar TF Current 0 4 -1 3 -0.002 0.000 0.002 0.004 0.006 0.008 0.010 2 Time (msec)

1 Microwave Power Detected Power Microwave

0

-1 -0.002 0.000 0.002 0.004 0.006 0.008 0.010 Time (msec) O mode Discharge (three pressure region observed)

O-Mode Discharge (i.e. E parallel to BT) 14 13 4x10-02 mbar 12 1-0.5 μbar 9x10-03 mbar 11 7x10-03 mbar 10 5x10-03 mbar 9 5-3 μbar 3x10-03 mbar 8 1x10-03 mbar 7 9x10-04 mbar 6 7x10-04 mbar 5 5x10-04 mbar 4 3 2

Edge Plasma Temperatur (eV) 1 40-7 μbar 0 -1 0.000 0.002 0.004 0.006 0.008 0.010 Time (msec) O mode Discharge : Dependence on BT

O Mode Discharge ( 7 μ bar) 7 BT 480, 90V 6 BT 680, 120V BT 850,150V 5

4 20 O Mode Discharge ( 0.5 μ bar)

3 18 BT 480, 90V

2 16 BT 680, 120V BT 850, 150V 1 14 12

Edge electron Temperature (eV) Temperature electron Edge 0

-1 10

-0.002 0.000 0.002 0.004 0.006 0.008 0.010 8 Time (msec) 6 O Mode Discharge ( 1 μ bar) 16 4

14 BT 480,90V 2 BT 680,120V 12 BT 850, 150V (eV) Temperature electron Edge 0

10 -2

8 -0.002 0.000 0.002 0.004 0.006 0.008 0.010

6 Time (msec)

4 2 Fast Bank : 680 V, Slow Bank : 120 V looks Edge electron Temperature (eV) Temperature electron Edge 0 optimum field for future plasma current shot -2 -0.002 0.000 0.002 0.004 0.006 0.008 0.010 with O-mode Polarization Time (msec) 480 , 90 V 680, 120 V 850, 150V O mode Discharge : Dependence on BT (7x10-06bar) O mode Discharge : Dependence on BT (1x10-06bar) 480 ,90V680,120 V 850,150V 480 , 90 V 680, 120 V 850, 150V O mode Discharge: Dependence on BT (.5x10-06bar) X mode Discharge (Edge temperature upto 20eV)

X Mode Discharge (40-07 μ bar) 5

4

3 6 X Mode Discharge (1-0.5 μ bar) 4x10-02 mbar 2 2x10-02 mbar 9x10-03 mbar 5 1 7x10-03 mbar TF Current 4 Microwave Power Detected 0 3

-1 1x10-03 mbar 2 -0.002 0.000 0.002 0.004 0.006 0.008 0.010 9x10-04 mbar Time (msec) 7x10-04 mbar 1 5x10-04 mbar

X Mode Discharge (5-3 μ bar) Microwave Power Detected TF Current 5 0

4 -1 -0.002 0.000 0.002 0.004 0.006 0.008 0.010 3 Time (msec)

2 5x10-03 mbar 3x10-03 mbar TF Current 1 Microwave Power Detected Power Microwave 0

-1 -0.002 0.000 0.002 0.004 0.006 0.008 0.010 Time (msec) X mode Discharge (Edge temperature up to 20eV)

X-Mode Discharge (i.e. E Perpendicular to BT) 20 18 2x10-02 mbar 1-0.5 μbar 9x10-03 mbar 16 7x10-03 mbar 14 5x10-03 mbar 3x10-03 mbar 12 1x10-03 mbar 10 9x10-04 mbar 8 5-3 μbar 7x10-04 mbar 5x10-04 mbar 6 4 2 Edge Plasma Temperature (eV) Temperature Plasma Edge

0 20-7 μbar -2 0.000 0.002 0.004 0.006 0.008 0.010 Time (msec) For Low BT, Vacuum around 0.5 micro bar is recommended: around 19eV measured at edge X mode Discharge : Dependence on BT

4.5 Xmode Discharge at 7 μ bar 4.0 14 Xmode Discharge at 1 μ bar 3.5 BT 480, 90V BT 680,120V 12 3.0 BT 850, 150V BT 480, 90V 2.5 10 BT 680,120V BT 850, 150V 2.0 8 1.5

1.0 6 0.5 4 0.0 EdgeTemperature Plasma (eV) -0.5 2

-0.002 0.000 0.002 0.004 0.006 0.008 0.010 Time (msec) 0 Edge Plasma Temperature (eV) -2 20 Xmode Discharge at 0.5 μ bar -0.002 0.000 0.002 0.004 0.006 0.008 0.010

BT 480, 90V Time (msec) BT 680, 120V 15 BT 850, 150V

10 Toroidal Coil Fast Bank : 480 V, Slow Bank : 90 Volts gives optimum field for future plasma 5 current shot with X-mode Polarization

0 This shows the requirement of BT changes Edge PlasmaTemperature (eV) from O to X mode Discharge -0.002 0.000 0.002 0.004 0.006 0.008 0.010 Time (msec) X mode Discharge : Dependence on BT (1x10-06bar) 480 ,90V680,120 V 850,150V X mode Discharge: Dependence on BT (.5x10-06bar) 480 ,90V680,120 V 850,150V GLAST III Discharge

(a) Toroidal field (b) Microwaves (c) Plasma current (d) Photodiode (Peak confirms formation of plasma current) Some of GLAST III Discharges with Hydrogen

012345678 012345678 1 0 20 -1 PF=1500 V -2

10 -3 PF=1500 V loop Ip (KA)

0 -4 V -10 -51 20 0 PF=1200 V -1 10 -2 PF=1200 V -3

loop 0

Ip (KA) -4 V -10 -52 20 1 PF=1000 V 0 10 -1

-2 PF=1000 V loop 0

Ip (KA) -3 V -10 -42 20 1 10 PF=800 V 0 -1

PF=800 V loop 0 -2

Ip (KA) Ip V -10 -3 20 -42 1 10 PF=600 V 0 -1

loop 0 PF=600 V -2 V -10 (KA) Ip -3 20 -41 10 PF=500 V 0 -1 PF=500 V

loop 0

-2 V -10 (KA) Ip -3 20 -41 10 PF=0 V

loop 0 0

PF=0 V V

-10 Ip (KA) -1 012345678 012345678 Time(ms) Time(ms) Working pressure: 4.0X10-4 mbar, Pre-ionization Source: Microwave (2.45 GHz), 800 watt, CS: Charging voltage 4.0kV, Capacity 6.6 mF, TF: FB Charging voltage 850 V, Capacity 3mF, SB Charging voltage 160 V, Capacity 600 mF, VF: Capacity 3 mF Courtesy of Z. Ahmad Future Goals

• Installation of 3kW source on GLAST III • Application of three microwave sources at 120 degrees around the GLAST III chamber. • Started the Physics & Engineering Design of New Medium Size targeting the following major Parameters: R=0.5 m, a=0.25 m, Aspect Ratio=2.0, Toroidal Field=0.5 Tesla, Plasma Current=300 kA, Pulse Length=100 ms, TF inside and CS outside geometry Thanks Thanks