Janus, a bidirectional, multifunctional plasma diagnostic

Wan, A. S.; Yang, T. F.; Lipschultz, B.; LaBombard, B.
August 1986
Review of Scientific Instruments;Aug1986, Vol. 57 Issue 8, p1542
Academic Journal
Janus is a multiple-function edge probe used to diagnose the Alcator C limiter shadow plasma whose components include two sets of identical diagnostics, each set facing a different direction. Included within each set of diagnostics are a retarding-field energy analyzer (RFEA), Langmuir probe, and calorimeter. Janus is constructed to make measurements both parallel and antiparallel to a magnetic field. It can withstand high heat fluxes and can be scanned perpendicular to the magnetic field in the limiter shadow. The RFEA can alternatively sample both the ion and electron parallel energy distribution functions during a tokamak discharge. From the Langmuir probe, one can infer electron temperature, density, and the plasma floating potential. The calorimeter independently detects the total parallel heat flux incident on an electrically floating plate. Together these three diagnostics enable detailed, localized edge plasma studies on Alcator C. This paper presents the design considerations for each of the diagnostics along with a brief summary of the analysis techniques. Some experimental results obtained using Janus will also be presented.


Related Articles

  • Electrical probe with guard and automatic positioner. García-Hernández, J. M.; López-Callejas, R.; Camps-Carvajal, E.; Benítez-Read, J. S. // Review of Scientific Instruments;Apr2000, Vol. 71 Issue 4 

    We present the design and construction of a diagnostic system of the plasma parameters by means of electrical probes. The novelties of the system are the protection provided to the electrical probe with a guard, thus minimizing the probe deterioration, and the automatic positioning device...

  • Plasma measurements with triple and single probes in an asymmetrical parallel plate rf plasma reactor Murata, Kinji; Kubo, Takashi; Kiwata, Hiroaki // Review of Scientific Instruments;Jul98, Vol. 69 Issue 7, p2681 

    Performs plasma measurements with triple and single probes in an asymmetrical parallel plate rf plasma reactor. Agreement on two probe characteristics with the single and triple probes; Connection of the compensation circuits to the probe system; Reason why the measurement results suffer from...

  • Edge plasma measurements near the minimum-B anchor cell of GAMMA10 using Langmuir probe and calorimeter arrays. Nakashima, Y.; Islam, M. K.; Natori, T.; Katanuma, I.; Ohki, T.; Watanabe, K.; Higashizono, Y.; Cho, T.; Ishimoto, Y. // Review of Scientific Instruments;Oct2004 Part I & II, Vol. 75 Issue 10, p4308 

    Edge plasma diagnostic system equipped in minimum-B anchor cell of the GAMMA10 tandem mirror is described together with the measured results. Several sets of the diagnostic element consisting of a Langmuir probe and a calorimeter are placed in array on the conducting plates installed in the east...

  • Determination of field line location and safety factor in TEXT-U Winslow, D. L.; Bengtson, Roger D.; Richards, B.; Craven, W. A. // Review of Scientific Instruments;Jan1997, Vol. 68 Issue 1, p396 

    Describes a technique for identifying a parallel connection between Langmuir probes and other diagnostics on the TEXT-U tokamak. Method for the identification of a magnetic field line; Separation of the amplitude and phase of driven potential fluctuations at the sensor probes from background...

  • The influence of magnetization strength on the sheath: Implications for flush-mounted probes. Gunn, J.P. // Physics of Plasmas;Dec97, Vol. 4 Issue 12, p4435 

    Evaluates whether or not flush-mounted probes (FMP) can be used routinely as plasma diagnostic tools, not only in tokamaks but also in any situation where strong, obliquely inclined magnetic fields are present. Use of one-dimensional particle-in-cell simulations; Behavior of ion current...

  • Langmuir probe technique for plasma parameter measurement in a medium density discharge. Hopkins, M. B.; Graham, W. G. // Review of Scientific Instruments;Sep86, Vol. 57 Issue 9, p2210 

    The development of a microcomputer-controlled electrostatic probe as a diagnostic technique is described. The technique uses cylindrical probes and the definitive theory of Laframboise to give rapid measurements of the plasma parameters in a medium density (1010 to 1012 cm-3) plasma including...

  • Preliminary design of a heavy ion beam probe diagnostic for the National Spherical Torus Experiment. Mull, F.H.; Crowley, T.P.; Schoch, P.M.; Connor, K.A. // Review of Scientific Instruments;Jan1999, Vol. 70 Issue 1, p959 

    Presents the preliminary design of a heavy ion beam probe (HIBP) for the National Spherical Torus Experiment. Primary purpose of the diagnostic probe; Principle of heavy ion beam probing; Beam attenuation and signal levels; Potential, density and particle flux measurements; Magnetic vector...

  • A heavy ion beam probe for the Madison Symmetric Torus. Shah, U.; Connor, K.A.; Lei, J.; Schoch, P.M.; Crowley, T.P.; Schatz, J.G.; Dong, Y. // Review of Scientific Instruments;Jan1999, Vol. 70 Issue 1, p963 

    Describes the development of a heavy ion beam probe for application on the Madison Symmetric Torus tokamak. Measurement of the plasma space potential, fluctuations in potential, electron density, fluctuating electron density and radial electric field; Design of the probe system; Reliability.

  • Simple heatable Langmuir probe for alkali plasmas Strele, Daniela; Koepke, Mark; Schrittwieser, Roman; Winkler, Patrick // Review of Scientific Instruments;Oct97, Vol. 68 Issue 10, p3751 

    Presents a small, simple, indirectly heatable Langmuir probe for measurements in alkaline plasmas. Heating element of the probe; Necessary heating power; Removal of the inevitable alkaline coating of the probe collector by sufficient heating; Various types of coating and their influence on the...


Read the Article


Sorry, but this item is not currently available from your library.

Try another library?
Sign out of this library

Other Topics