The primary activities at Alcator C-Mod during the first quarter of FY99 were: data analysis and presentation of physics results, reassembly of the machine, installation of diagnostics, both invessel and external, installation of the new RF antenna, preparation of the DNB, and continued participation in the critical assessment of fusion science. A more detailed account of these activities follows.
Scientific Results
Core Confinement Results
Regimes of High Confinement (H-mode) have been studied extensively in Alcator C- Mod. Plasmas with no Edge Localized Modes (ELM-free) have been compared in detail to the new Enhanced Da (EDA) regime. EDA discharges have only slightly lower energy confinement than comparable ELM-free ones, but show markedly reduced impurity confinement. Thus EDA discharges do not accumulate impurities, typically have a lower fraction of radiated power and appear to have steady-state potential.
Perhaps the most important questions that we wish to answer concern the
physical mechanism that leads to EDA behavior and its applicability in reactor
regimes. In the EDA regime, the edge pedestal gradients are relaxed by a
continuous rather than an intermittent process. Even when small ELMs are seen in
the EDA regime, these do not seem to carry out any significant
amount of energy or particles, nor do they diminish the size of the pedestal. In
contrast, type I ELMs are believed to be a relaxation oscillation driven by the
improved transport in the H-mode barrier and limited by pressure driven or current
driven MHD modes. Hegna[Phys. Plasmas 3, (1996) 584] and Connor[``Theory of Fusion Plasmas'',
edited by Connor, Sindoni, and Vaclavik, (Bologna: Editrice Composotiori, 1997), 441]
have formulated a picture for ELM behavior by calculating stability in the
Jedge,a plane (where Jedge is the edge current
density and a is the normalized edge pressure gradient, Rb¢). In this picture, the
edge of an H-mode plasma evolves to the pressure driven ballooning limit on a
transport time scale, then toward the current driven ``peeling mode'' limit on a current
diffusion time scale. The ballooning limit is seen as a ``soft'' limit, where transport is
increased but the pedestal remains intact. ELMs are identified with the peeling limit,
which is essentially an external kink, and results in destruction of the barrier. (We
note that one might expect to see an increase in edge turbulence as an ELM-free
discharge approaches its first large ELM; in fact this is not generally observed.) In
this picture, one might identify EDA as a manifestation of the ballooning limit.
Some of the dependencies showing the ``boundaries'' between EDA and ELM-free confinement
as shown in Fig.1. The
observed dependences on triangularity and safety factor
suggests that MHD stability does play an important role. Superficially, the
dependences are reminiscent of those reported by Miller [Miller et al., Physics of
Plasmas 4 (1996) 1062], where the plasma edge
was shown to have the easiest access to second stability at moderate and at
higher q95. However, to make that connection, we would have to identify EDA as the
more MHD stable regime. This view is contradicted by the increased level of
turbulence and decreased particle confinement seen experimentally in EDA.
The MHD stability of the pedestal is rather difficult to analyze however, since it depends critically on the local magnitude of edge current density and pressure gradient. Thus individual flux surfaces within the pedestal may be near one of several stability limits. The effects of shaping and safety factor shown in Fig. 1 cannot be explained by a simple S/q2 dependence (where S is the shear). Resolution of these issues must await improved measurements of these profiles planned for future experimental campaigns. The observed effects of neutrals may ultimately be explained within the same model of the peeling mode. We note that high levels of neutrals in the plasma edge can lower the edge temperature through direct cooling (via charge exchange and convective losses) or by weakening the transport barrier via shear flow damping. We have observed slower mode rotation at high neutral densities, which can be interpreted as damping of the underlying perpendicular flows. Regardless of the mechanism, lower edge temperatures are observed at high neutral densities, from which we can infer higher collisionalities and smaller edge currents from both the Ohmic and bootstrap drives. These effects will tend to keep the plasma edge away from the peeling boundary and thus suppress type I ELMs. Finally we note the possible connection to theories of drift Alfven turbulence. Three dimensional electromagnetic simulations show that plasmas at higher collisionality are subject to turbulence due to the non-linear evolution of resistive ballooning modes and ion thermal gradient instabilities. It is possible that EDA is a manifestation of this turbulence.
Divertor and Edge Results
Alcator C-Mod has operated a good confinement H-mode plasma together with a dissipative divertor and low core Zeff. As shown in Fig. 2, the initially attached H-mode plasma is characterized by steady-state energy confinement enhancement factor HITER89P of 1.9, central Zeff of 1.1, power flowing into the scrape-off-layer of 2.5 MW, and total (divertor and core) radiated power fraction of ~ 50%. Feedback control of a nitrogen gas puff was then used to increase radiative losses in both the edge and divertor plasmas, while simultaneously maintaining a core plasma with HITER89P ~ 1.6, Zeff ~ 1.4, and PSOL £ 2 MW. The nitrogen puff increases radiation in the divertor and core/edge plasmas by similar amounts, accomplishing a nearly 100% radiative state. The outer divertor detaches although the inner divertor remains attached. Measurements of the heat flux to the divertor plates using fast thermocouples embedded in the outer divertor plates show that the high parallel heat fluxes ( ³ 0.4 GW m-2) of the attached state have been lowered to very low levels ( £ 0.05 GW m-2) by this dissipative divertor.
A number of the essential features of the detachment process have been explored. Volume recombination in the divertor, although measurable, is not significant in these dissipative H-mode plasmas. This indicates that the loss in ion current to the plates is a result of other processes, most likely a reduction of the ion source. There is a significant difference in the ion and neutral flow velocities measured in the divertor under these detached conditions. The friction from ion-neutral collisions arising from this parallel flow differential is consistent with the observed electron pressure loss along field lines. Neutral power losses in the divertor have been measured. It is seen that £ 10% of the total divertor radiated power losses are due to the charge-exchange process. Screening, compression, and enrichment of argon are reduced a factor of about two after divertor detachment. The effect of different impurity gases on detachment and the H-mode pedestal was also investigated. The use of recycling gases with Zs higher than nitrogen, e.g. neon, argon, and krypton, leads to enhanced radiation at the edge of the main plasma but not in the divertor. Nitrogen puffing increases radiation in both regions and results in divertor detachment. Divertor radiation appears to be more effective than edge plasma radiation in inducing divertor detachment. Use of these higher-Z gases also results in a greater degradation of core confinement than does nitrogen puffing. This is possibly due to the location of the radiation peak, which for the higher-Z gases is inboard of the pedestal location.
Divertor detachment in enhanced confinement plasmas has been achieved in many limiter and divertor tokamaks using puffed impurities. However, either the Zeff arising from the puffed impurities is too high or the energy degradation is too great to meet the ITER requirements of HITER89P > 2.4 and Zeff < 1.6. These Alcator C-Mod results have shown that combined dissipative divertor H-mode operation can be achieved with high parallel power flux, qSOL ~ 0.5 GW m-2, good confinement, HITER89P ~ 1.6, and a clean core plasma, Zeff £ 1.4. The energy enhancement factor achieved in Alcator C-Mod needs to be improved to achieve the ITER requirement stated above. In C-Mod there is a linear relation between the edge temperature and global confinement. If the edge temperature is enhanced by better wall-conditioning, better tailoring of the impurity puff, using different impurites, or improving the screening of impurities from the core plasma, a better H-factor should result. However, in any scenario, the power flowing to the divertor must be kept at an acceptable level.
Recombination
Utilizing measurements of ne and Te along the same viewing chords as Balmer series line emission, we have been able to determine the local recombination rate as a function of position in the divertor. In ohmic plasmas that become deeply detached, we find that the recombination region expands from the divertor plate towards the x-point, roughly along flux surfaces, as the core density increases and detachment deepens. Comparing the total volumetric recombination ion sink to the plate ion current remaining during detachment, we find that volume recombination eliminates between 10% and 75% of the ion flow before it reaches the divertor plate. The lowest values are for H-mode plasmas where the detachment is induced by injection of N2 gas and the power flow into the ionization region is decreased (see above). Recombination is most important as an ion sink for C-Mod discharges when detachment is induced through D2 gas puffing with the accompanying core density rise. The remaining fraction of the observed ion current reduction is inferred to be due to reductions in the ion source rate upstream from the plate. The inferred ion source rate is consistent with a model relating changes in the divertor ion source to changes in the power flowing into the divertor region.
A scaling for the density in the recombining region is found to be nerecomb µ (nemain)0.8 ×PSOL2/7 . An implication of this scaling is that the recombining region is found at an approximately constant location along the pressure gradient in the detached region.
Volume recombination can be very important in determining the reduction of ion current to the plates during detachment. Changes in the upstream ion source rate brought about by changes in power flow are equally important. These results also indicate that volume recombination is not a necessary condition for detachment (for either ion current reduction or pressure loss).
Edge modelling
Modelling of the edge plasma of C-Mod with the multi-fluid code UEDGE has progressed. This code solves the steady state Braginskii equations for ions and electrons and the Navier-Stokes equation for the neutrals in the real geometry of the edge plasma. The anomalous transport is adjusted to match experimental profiles of plasma density and temperature in the SOL. It has been shown in the modelling that, if the radial particle transport in the SOL is modeled as j=-DÑn, then a spatially constant D does not match the experimental SOL density profiles as given by scanning probe data. However using a D profile which grows rapidly towards the wall results in a good match to the density profile. Such spatially non-uniform radial particle transport can also be represented by a uniform D combined with a radial pinch. A spatially constant anomalous heat diffusivity is sufficient to model the Te profiles. Reasonably good matches with experimental plasma density and temperature profiles, midplane gas pressure and the flow velocity were achieved in the code for two modeled shots by adjusting the anomalous transport. The input power, Psol, was taken from the experiment. One of the modeled shots had high midplane gas pressure, Pmid, and the other one had low Pmid. Comparing the `effective diffusion coefficient' D in these two cases, one could see that the general shape of the radial D profile is the same, however the magnitude of D is much larger in the high Pmid case. This is consistent with the ideas that high Pmid reflects a high level of particle transport from the core. According to the modelling in the low Pmid case, neutrals come mostly from the divertor, while in the high Pmid case the main chamber wall itself becomes a significant source of gas, providing 50% or more of neutrals. Since midplane pressure grows with the core density, it appears that it is the high density of C-Mod plasmas that makes C-Mod a special case with quite high transport from the core. Analyses of the radial heat flux in the SOL for the two modeled shots show that in the high Pmid case, heat convection by the radial particle flux and heat conduction by CX neutrals can account for a significant fraction of Psol (20-50%). These two ``classical'' mechanisms of heat transport dominate the heat far into the SOL (r ~ 5 mm and more), even in the low Pmid case.
In collaboration with Steve Lisgo at the University of Toronto,
we have learned how to both run and modify the U of Toronto LIM code. We will use the code in the study
of C-Mod ``plume'' data. (Plumes are generated by small gas puffs from the tip of a reciprocating probe.)
The code generates full 3D data which can then be
integrated along either one or two dimensions to produce 2D contour
plots or 1D profiles. This will be used in comparing the simulations
to the data from the CCD cameras which view the plumes.
RF Research
Data from loop probes on the inner wall have been analyzed in order to understand the changes in fast wave propagation caused by sawteeth. The loop probes are opposite one of the fast wave antennas. During fundamental minority heating in D(H) at 5.4 T, the signals from the loop probes often show an abrupt change at the time of a sawtooth crash. During shots for which the hydrogen concentration is low, the signals increase at the time of the sawtooth crash, but during shots when the hydrogen concentration is high, the signals decrease at the time of the crash. The low-hydrogen-concentration behavior can be understood in the context of a single-pass analytic model by invoking the well-known redistribution of hot minority ions by the sawtooth crash, which results in a decrease in the minority temperature at the resonance layer and hence an increase in transmission. This hypothesis alone cannot also explain the behavior at high-hydrogen concentration. An alternative hypothesis is that the hydrogen fraction at the resonance layer decreases at the sawtooth crash. However this effect would also cause an increase in transmission at low hydrogen fraction. At high hydrogen fraction, the transmission is dominated by the wave polarization, which becomes less favorable (if absorption is desired) as the hydrogen fraction increases, so that a decrease in hydrogen fraction would cause a decrease in transmission, as is observed. These two competing explanations are the subjects of ongoing analysis.
MHD Research
Studies are ongoing on the high frequency coherent MHD activity found in the Alfven eigenmode range of frequencies. Under low or reversed shear conditions with strong ICRF heating during the current rise, magnetic fluctuations in the range of 150 - 450 kHz are observed with rapidly changing frequencies as the q profile evolves. Similar high frequency magnetic fluctuations are observed during steady-state Enhanced Da (EDA) with frequencies of 520 kHz to 700 kHz. These modes appear to rotate in the electron drift direction, which is unusual for Alfven eigenmodes. The rapid frequency chirps under low shear conditions and the unusual rotation direction in EDA are being investigated theoretically in collaboration with Prof. Herb Berk of the University of Texas at Austin Institute for Fusion Studies.
Operations and Diagnostics
Alcator C-Mod has just begun the CY99 run campaign. As of January 27, tokamak plasmas of 0.6 MA and ~ 300 ms duration are being produced. The machine is cleaning up shot-to-shot. The magnet is being operated routinely at 5.4 T. Much work during the past quarter has been done to reach this point.
A partial list of the successfully completed reassembly tasks follows:
Among the numerous diagnostic rearrangements accomplished for this run campaign was the movement of the ECDC launch from F port to H port. (The ECDC system is C-Mod's system for discharge cleaning.) The launch remains an outside launch, but is innovative in that there is no longer a line-of-sight view of the main chamber from the launch point. The microwaves must be relected at least once from the walls of the horizontal port extension before reaching the main plasma chamber. This new system has been successful.
An existing one meter Ebert spectrograph has been modified to enable dedicated high resolution measurements of the Balmer alpha lines of hydrogen and deuterium, in order to monitor the time history of the atomic D/H ratio at the edge of all discharges. The spectrograph has been outfitted with a 64 pixel reticon photodiode array detector, and has been calibrated using a lamp containing a mixture of hydrogen and deuterium. The measured instrumental resolution is about .015 nanometers (half width at 1/e). Light is collected using a fiber optic view at K port, with selectable polarizers to discriminate between the pi and sigma Zeeman components of the emission.
The PSFC Office of Environment, Safety, and Health now has many of its operating procedures online. This site provides procedures for handling diborane, cryogenic materials, and caustics and acids, among many others. It can be found at
All procedures will eventually be available online including ones for invessel work, boronization, electroplating, and handling compressed gases.
Collaborations and Participation in the Fusion Science Community
As part of a study for a ``reduced cost'' burning plasma device, M. Porkolab et al. have proposed a new reduced size, superconducting tokamak. It has the twin primary goals of studying burn physics either in an inductively driven standard tokamak (ST) mode of operation, or in a quasi-steady state advanced tokamak (AT) mode sustained by non-inductive means. This is achieved by reducing the radiation shield thickness protecting the superconducting magnet by 0.34 m relative to the ITER design and limiting the burn mode of operation to pulse lengths as allowed by the TF coil warming up to the current sharing temperature. High gain (Q @ 10) burn physics studies in a reversed shear equilibrium, sustained by RF and NBI current drive techniques, may be obtained. The details of the proposed concept can be found in the proceedings of 17th IAEA Fusion Energy Conference (Yokohama, Japan 1998).
Our collaborators from INEEL/Lockheed Martin, W.J. Carmack and S.V. Gorman, have written a report on the dust collected from Alcator C-Mod in April of 1998. Details of particle composition and size distributions are discussed in great detail.
Progress continued on the development of the high resolution ECE diagnostic. Perry Phillips (UT-FRC) visited the PSFC to work with John Heard (AU) to complete the fitup of the in-vessel mirrors, internal waveguides, and windows on the F-Port flange. On completion, John travelled to Auburn to complete the spatial calibration of the ECE optics. This calibration will support later data analysis. Don Patterson (UT-FRC) completed testing of the high frequency data acquisition Camac at UT-FRC and began stuffing the Camac crates for shipment to MIT.
Bill Rowan (UT-FRC) is on-site full time coordinating the U. Tx/C-Mod collaboration. Ron Bravenec (UT-FRC) has also been on-site to lay out the new electronics rack for BES, to assist in installation of MSE/BES optics, and to participate in the APS-DPP poster review.
Gerd Schilling of PPPL has been on-site for much of the quarter.
Les Gereg, Joe Frangipani, Dave Cylinder, and Norton Bretz from PPPL were on-site for most of the month pior to machine closure in order to work on the new antenna and the MSE diagnostic. Dave Johnson has visited periodically to work with us on the edge Thomson scattering system. David Mikkelsen, also from PPPL, visited C-Mod in late November and in late January. He is working with Martin Greenwald on transport modelling.
Jim Weaver and Bill Noonan from the University of Maryland have brought on-line the U. Md. high resolution spectrometer. It will use many of the fiber optic views available on C-Mod.
Ricky Maqueda from LANL was at MIT from Jan. 15-20, working on his IR periscope and camera system.
Selected Domestic Travel
Nearly all C-Mod scientists and most graduate students attended the APS DPP meeting in New Orleans November 16-20. Three invited talks, ten contributed talks, and 34 posters were given on Alcator C-Mod results by Alcator personnel and collaborators. The abstracts for these presentations are posted on the WEB at
The first in a series of Ignitor Working Group meetings was held on 3 - 4 November 1998 in the Physics Department here at MIT. Martin Greenwald presented a talk on confinement in C-Mod as compared with Ignitor. After the meeting, Stewart Zweben and Robert Budny visited the PSFC on November 5 and held discussions with various members of the staff on fast particle physics issues and transport. Stewart Zweben discussed the installation of a tangential (re-entrant fiber bundle) intensified CCD system to look at changes in turbulent transport during the L-H mode transition. This device would be designed during the next run period for installation at the next major break.
Paul Bonoli, Ian Hutchinson, and Miklos Porkolab were in Germantown, DOE, on November 5th, to present a Lower Hybrid Current Drive Proposal, together with Stefano Bernabei and Rich Hawryluk from PPPL. A joint plan developed by MIT and PPPL to do Advanced Tokamak physics experiments on C-Mod with LHCD profile control was discussed.
Miklos Porkolab visited General Atomics on Monday, Nov. 30th, and gave a presentation on the Lower Hybrid Current Drive Proposal for C-Mod (mentioned above). He also participated in discussions clarifying AT physics issues and requirements on profile control in ongoing tokamak experiments, including C-Mod, DIII-D and tokamaks abroad.
On December 16 and 17 Josh Stillerman attended a Department of Energy workshop on remote collaboration in Germantown Md.
Martin Greenwald travelled to Washington D.C. in January to attend a meeting of the ESnet steering committee (ESSC). Issues discussed included upgrades to international connections; new requirements expected from the SSI (Scientific Simulation Initiative); and possible new directions for the ESnet Coordinating Committee (a technical committee reporting to the ESSC.) Half a day was devoted to relationships with the DOE program offices. About 10 contract monitors representing most of the SC programs attended this session.
Martin Greenwald also attended the PAC meeting for the fusion SSI project held at PPPL. The purpose of the meeting was to get feedback on a whitepaper that had been prepared by the management team and to begin planning for the proposal process. The PAC, which was unusually large, consisted of 13 specialists from both inside and outside the fusion community. Their response to the whitepaper was generally quite favorable, though they made numerous suggestions for improvements. The final version of the whitepaper is due by Feb. 28. Assuming a formal announcement of the initiative (expected from Vice President Gore), OFES will publish a ``notice of interest'' by April 15.
International Travel
Paul Bonoli, Bob Granetz, Martin Greenwald, Ian Hutchinson, Bruce Lipschultz, Earl Marmar, Miklos Porkolab, John Rice, and Steve Wukitch attended the 17th IAEA Fusion Energy Conference in Yokohama Japan. They presented four oral and three poster papers at the conference.
John Rice visited LHD in Toki, Japan for the week of October 26-30.
October 26-30 Bruce Lipschultz attended the ITER Divertor meeting at the Naka site (JAERI). He also visited the Tokai site to see JFT-2M and the ITER vacuum vessel sector. Bob Granetz attended the ITER MHD/Control/Disruptions expert group meeting also at the Naka site.
Amanda Hubbard visited the Centre Canadien de Fusion Magnetique and INRS-Energie, in Varennes, Quebec, serving as external examiner for a Ph.D. thesis.
Miklos Porkolab attended the VLT (Virtual Laboratory for Technology) PAC meeting at UCSD, San Diego, on December 10,11.
During his visit in Denmark, graduate student Thomas Sunn Pederson visited Risoe National Laboratory on Jan. 5, and gave a talk on ``Edge plasma phenomena measured by the x-ray imaging diagnostic''.
Ian Hutchinson visited IPP-Julich in Germany to present an invited series of graduate student lectures on plasma diagnostics as part of the ``GraduiertenColleg'' program in plasma physics at German Universities. He also had discussions regarding experiments being carried out on ECDC at a small dedicated toroidal facility. Topics discussed with the TEXTOR group included the possibility of studying rotation in ICRF-only TEXTOR discharges, to compare with results obtained on C-Mod; RI-mode results from TEXTOR; perpendicular velocity measurements with Mach probes, and results of siliconization experiments on TEXTOR. He presented a research colloquium on ``Plasma Velocity Measurements on Alcator C-Mod''.
Near Term Plans
Our near term plans are focussed on the present run campaign, which has begun with the start-up phase. It is anticipated that physics studies will begin sometime in February. A number of MiniProposals have already been submitted, but proposals are still being solicited. Fifteen new MiniProposals have been approved. The C-Mod Run Schedule on the Web has been updated. Overall plans for the 1999 Campaign can be found at http://www.psfc.mit.edu/cmod/run_schedule.html. Daily operations information can be found on the C-Mod Operations Calendar at http://www.psfc.mit.edu/cgi/calendars/cmod, which is updated as information becomes available. Those with access to the online OPS bulletin board are advised to check there for the most up-to-date schedule information.
The major new aspects of this campaign include the doubling of the available RF heating power, the use of the DNB and its associated diagnostics, and the testing and use of the controllable, divertor by-pass ``flappers''.
``Analysis of sawtooth phenomena in Alcator C-Mod'', F. Bombarda, Bonoli, Coppi, Granetz, Hubbard, Irby, Migliuolo, O'Shea, Rice, Takase, Wolfe, G. Huysmans, W. Kerner, Nuclear Fusion, 38, p. 1861-1869,
``High Confinement Dissipative Divertor Operation on Alcator C-Mod'', J.A. Goetz, et al., to be published in Phys. of Plasmas. Also available at: http://www.psfc.mit.edu/library/98ja/98ja036_abs.html
``Transport in Alcator C-Mod H-Modes'',M. Greenwald, R. Boivin, P. Bonoli, R. Budny, C. Fiore, J. Goetz, R. Granetz, A. Hubbard, I. Hutchinson, J. Irby, B. LaBombard, Y. Lin, B. Lipschultz, E. Marmar, A. Mazurenko, D. Mossessian, C.S. Pitcher, M. Porkolab, J. Rice, W. Rowan, J. Snipes, G. Schilling, Y. Takase, J. Terry, S. Wolfe, J. Weaver, B. Welch, S. Wukitch, be published in Phys. of Plasmas. Also available at: http://www.psfc.mit.edu/library/98ja/98ja034_abs.html
``The role of particle sources and sinks in Alcator C-Mod detached divertor discharges'', B. Lipschultz, J.L. Terry, C. Boswell, J.A. Goetz, A.E. Hubbard, S.I. Krasheninnikov, B. LaBombard, D.A. Pappas, C.S. Pitcher, F. Wising, and S. Wukitch, to be published in Phys. of Plasmas.
``H-Mode regimes and observations of central toroidal rotation in Alcator C-Mod'', M. Greenwald; J. Rice; R. Boivin; P. Bonoli; R. Budny; C. S. Chang; D. Ernst; C. Fiore; J. Goetz; R. Granetz; A. Hubbard; I. Hutchinson; J. Irby; B. LaBombard; B. Lipschultz; E. Marmar; D. Mossessian; M. Porkolab; W. Rowan; J. Snipes; G. Schilling; Y. Takase; J. Terry; S. Wolfe; J. Weaver; B. Welch, to be published in Proceedings of 17th IAEA Fusion Energy Conference (Yokohama, Japan 1998). Also available at: http://www.psfc.mit.edu/library/98ja/98ja030_abs.html
``Advanced tokamak burning plasma experiment'', M. Porkolab, P.T.Bonoli, J Ramos, J. Schultz, W.N. Nevins, to be published in Proceedings of 17th IAEA Fusion Energy Conference (Yokohama, Japan 1998).
``Detached divertor plasmas in Alcator C-Mod: a study of the role of atomic physics'', B. Lipschultz et al., to be published in Proceedings of 17th IAEA Fusion Energy Conference (Yokohama, Japan 1998).
``Scaling of H-mode pedestal characteristics in DIII-D and C-Mod'', R.S. Granetz et al., to be published in Proceedings of 17th IAEA Fusion Energy Conference (Yokohama, Japan 1998).
``ICRF heating experiments in Alcator C-Mod'', S. Wukitch et al., to be published in Proceedings of 17th IAEA Fusion Energy Conference (Yokohama, Japan 1998).
``Modelling of Advanced Tokamak Physics Scenarios in Alcator C-Mod'', P.T. Bonoli, et al., to be published in Proceedings of 17th IAEA Fusion Energy Conference (Yokohama, Japan 1998).
``Overview of recent results form the Alcator C-Mod Tokamak'', E.S. Marmar, et al., to be published in Proceedings of 17th IAEA Fusion Energy Conference (Yokohama, Japan 1998).