A helicon based pre-ionization source has been developed and installed on the Helicity Injected Torus with Steady Inductance (HIT-SI) spheromak. The source initiates plasma breakdown by injecting impurity-free, unmagnetized plasma into the HIT-SI confinement volume. Typical helium spheromaks have electron density reduced from (2–3) × 1019 m−3 to 1 × 1019 m−3. Deuterium spheromak formation is possible with density as low as 2 × 1018 m−3. The source also enables HIT-SI to be operated with only one helicity injector at injector frequencies above 14.5 kHz. A theory explaining the physical mechanism driving the reduction of breakdown density is presented.

1.
T. R.
Jarboe
,
C.
Akcay
,
M. A.
Chilenski
,
D. A.
Ennis
,
C. J.
Hansen
,
N. K.
Hicks
,
R. Z.
Aboul Hosn
,
A. C.
Hossack
,
G. J.
Marklin
,
B. A.
Nelson
,
R. G.
O’Neill
,
P. E.
Sieck
,
R. J.
Smith
,
B. S.
Victor
,
J. S.
Wrobel
, and
M.
Nagata
,
Nucl. Fusion
51
,
063029
(
2011
).
2.
P. E.
Sieck
,
T. R.
Jarboe
,
V. A.
Izzo
,
W. T.
Hamp
,
B. A.
Nelson
,
R. G.
O’Neill
,
A. J.
Redd
, and
R. J.
Smith
,
Nucl. Fusion
46
,
254
(
2006
).
3.
M.
Greenwald
,
Plasma Phys. Controlled Fusion
44
,
R27
(
2002
).
4.
B. S.
Victor
,
T. R.
Jarboe
,
A. C.
Hossack
,
D. A.
Ennis
,
B. A.
Nelson
,
R. J.
Smith
,
C.
Akcay
,
C. J.
Hansen
,
G. J.
Marklin
,
N. K.
Hicks
, and
J. S.
Wrobel
,
Phys. Rev. Lett.
107
,
165005
(
2011
).
5.
F. F.
Chen
,
J. Vac. Sci. Technol. A
10
,
1389
(
1992
).
6.
D. A.
Ennis
,
B. S.
Victor
,
J. S.
Wrobel
,
C.
Akcay
,
T. R.
Jarboe
,
G. J.
Marklin
,
B. A.
Nelson
, and
R. J.
Smith
,
Nucl. Fusion
50
,
072001
(
2010
).
7.
C. T.
Holcomb
, Master's thesis,
University of Washington
,
1999
.
8.
T.
Ziemba
,
J.
Carscadden
,
J.
Slough
,
J.
Prager
, and
R.
Winglee
, “
High power helicon thruster
,”
41st AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit
,
Tucson, AZ
, 3–10 July
2005
.
9.
R. G.
O'Neill
,
R. J.
Smith
,
C.
Akcay
,
W. T.
Hamp
,
R. Z.
Aboul Hosn
,
T. R.
Jarboe
,
A. J.
Redd
,
P. E.
Sieck
,
G. L.
Sutphin
, and
J. S.
Wrobel
,
J. Fusion Energy
26
,
131
(
2007
).
10.
J. S.
Wrobel
,
C. J.
Hansen
,
T. R.
Jarboe
,
R. J.
Smith
,
A. C.
Hossack
,
B. A.
Nelson
,
G. J.
Marklin
,
D. A.
Ennis
,
C.
Akcay
, and
B. S.
Victor
,
Phys. Plasmas
20
,
012503
(
2013
).
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