H-1 Heliac: Parameters

1
H-1 Heliac Parameters

• 3 period heliac 1992
• Major radius 1m
• Minor radius 0.1-0.2m
• Vacuum chamber 33m2
• Aspect ratio 5
• Magnetic Field 1 Tesla (0.2 DC)
• Heating Power 0.2(0.4)MW GHz ECH 0.3MW 6-25MHz
  ICH
• Parameters achieved / expected
• n 3e18/1e19
• T 100eV(Ti)/0.5-1keV(Te)
• ? 0.1/0.5

2
H-1 Heliac Parameters
Complex geometry requires minimum 2D diagnostic

• 3 period heliac 1992
• Major radius 1m
• Minor radius 0.1-0.2m
• Vacuum chamber 33m2
• Aspect ratio 5
• Magnetic Field 1 Tesla (0.2 DC)
• Heating Power 0.2(0.4)MW GHz ECH 0.3MW 6-25MHz
  ICH
• Parameters achieved / expected
• n 3e18/1e19
• T 100eV(Ti)/0.5-1keV(Te)
• ? 0.1/0.5

Cross-section of the magnet structure showing a
3x11 channel tomographic diagnostic
3
Plasma production and heating resonant and
non-resonant RF

• Non-resonant heating is flexible in B0, works
  better at low fields.
• Resonant heating is much more successful at high
  fields.

ltnegt 1018m-3
helicon/frame antenna
Update with helium, Tesla
? ?Chon axis
Magnetic Field (T)
4
2D electron density tomography
Helical axis ? non-circular ? need true 2D
coherent drift mode in argon, 0.08T
H density profile evolution (0.5T rf)
Raw chordal data
Tomographically inverted data
5
Ion Temperature Camera
Intensity temperature
rotation
Hollow Ti at low B0
radius
0 10 20 30 time (ms)
6
Confinement transitions in H-1
Parameter space map, ? 1.4
Pressure (Is) profile evolution during
transition
PRF (kW)
transition
B0(T)

• many features in common with large machines
• associated with edge shear in Er
• easily reproduced and investigated

7
ExB and ion bulk rotation velocity in high
confinement mode magnetic structure causes
viscous damping of rotation
Bulk Rotation Impeded
Radial force balance
Vp, Vt ltlt VExB  1/(neB) dPi/dr
Mass (ion) flow velocities much smaller than
corresponding VExB
8
ExB and ion bulk rotation velocity in low and
high confinement modes
Radial force balance
Vp, Vt ltlt VExB  1/(neB) dPi/dr
Mass (ion) flow velocities much smaller than
corresponding VExB
Fluctuations are Doppler shifted by electron ExB
drift
9
Radial force balance
Radial force balance is dominated by the ion
pressure gradient and the radial electric field
and is satisfied on average
10
Ion Temperature Camera
Hollow Ti at low B0
Ti as rf power is ramped