1. Effect of Faraday shields on capacitive coupling
D.D. Blackwell and F.F. Chen, 2D imaging of a helicon discharge,
Plasma Sources Sci. Technol. 6, 569 (1997)
No shield
With shield

2. m = +1 mode much stronger than m = –1
D.D. Blackwell and F.F. Chen, 2D imaging of a helicon discharge,
Plasma Sources Sci. Technol. 6, 569 (1997)
m = –1
m = +1

3. Development of a time-resolved energy analyzer
D.D. Blackwell and F.F. Chen, Time-resolved measurements of the EEDF in a helicon plasma, Plasma Sources Sci. Technol. 10, 226 (2001)
RF modulated electron gun
for calibration
2-electrode gridded analyzer
with RF response

4. Time-resolved EEDFs show no fast electrons above a threshold of 10 -4
F.F. Chen and D.D. Blackwell, Upper limit to Landau damping in helicon discharges, Phys. Rev. Lett. 82, 2677 (1999)
I-V swept by oscillating Vs
I-V at two RF phases
Loading resistance agrees with calculations w/o L.D.
Injecting a current causes a beam-plasma instability

5. Development of an RF J-dot probe
D.D. Blackwell, T.G. Madziwa, D. Arnush, and F.F. Chen, Evidence for Trivelpiece-Gould modes in a helicon discharge, LTP-106 (June, 2001)

6. Evidence for Trivelpiece-Gould modes
D.D. Blackwell, T.G. Madziwa, D. Arnush, and F.F. Chen, Evidence for Trivelpiece-Gould modes in a helicon discharge, LTP-106 (June, 2001)
"Wings" are seen in Jz
but not in Bz.
"Wings" are not predicted by
theory if TG modes are neglected.