Quarterly OFES Teleconference 22 Jan 2015

Agenda

• Earl Marmar: Current C-Mod Staffing, Graduate Student Status

• Martin Greenwald: Run Planning • Jim Irby: Facility • Brian LaBombard: NSTX-U collaborations • Jerry Hughes: DIII-D collaborations • International Collaborations

– Steve Wukitch: Long Pulse RF and High Z PFCs – Paul Bonoli: Control and Scenarios

Current MIT C-Mod Staffing

• Includes those directly supported from C-Mod Cooperative Agreement, ITPA/Data Preservation and MDSplus grants, and A. White Early Career Award

• Does not include international collaboration grants • Does not include personnel supported by indirect charges

Personnel FTE Faculty 0.8 Research Scientists 11.3 Post-Docs 4.2 Research Assistants (Grad Students)

9.2

Engineers 19.6 Computer staff 4.5 Technicians 16.7 Drafters 3.0 Administrative Staff 2.11

Graduate Student Status 2015/01/21

Run Planning for 2015 Campaign

C-Mod Quarterly Review – 1/22/15 Presented by Martin Greenwald

Status and Plans

C-Mod Quarterly 1/22/15 Run Planning 2

● As of the end of FY2014, we had ~34 days = 8 ½ run weeks of high-priority experiments lined up (we planned the campaign through 2015)

– Boundary – 13 days (many waiting on AIMS)

– Pedestal – 4.6 days

– Core transport – 4.4 days

– ITER – 4.5 days

– RF – 5.3 days

● Topical groups are currently developing priorities for 2015 – seems likely that many but not all of these experiments will carry over.

● We’ll complete this process by the end of Jan and then set overall priorities and allocations

● No formal research forum this year

A Few Highlights of the Upcoming Campaign

C-Mod Quarterly 1/22/15 Run Planning 3

● Experiments for 2015 JRT (impact of off-axis LH current drive)

● Exploit accelerator upgrade for AIMS

● Feedback control of divertor detachment

● I-mode studies at 8 T

● ICRF Plasma-edge interactions with field-aligned antenna: impurity control and antenna characterization

● Exploit “shoelace” antenna – for study and control of active short-wavelength electromagnetic modes in pedestal

● Look for signatures of ETG with new PCI detector and compare with multi-scale gyrokinetic simulations

● Early run time for 2016 JRT (Disruptions)

Facility Status 01/22/2015

Outline

• Machine Status • Alternator • Engineering Systems • Diagnostic Systems • In-vessel work • Short Term Schedule

Machine Status

• FY2014 campaign began on 1/29/14 and ended 8/27/14 • 11.37 research weeks accomplished (95% of 12 week target) • C-Mod was brought up-to-air on 11/21/14 • In-vessel work began 12/08/14

MIT Alternator

• A ground fault indication during application of excitation to the alternator field winding occurred on 08/28/14

• Bids from several vendors were assessed and an excellent vendor was selected • Perform planned alternator and flywheel inspection • Locate fault in rotor and repair • Vendor arrived on-site on 10/20/14

• Insurance will cover all costs associated with the repair

MIT Alternator

• A crack in the pole#4, coil#1, top turn, just as it exited the rotor forging slot was found • Location of high stress • Crack growth since 1997??

Fault location

Rotor forging

New end turn

1

2

3 4 5

MIT Alternator

• Repair • End turn was cut off well into forging slot at low stress region • Removed section was tested: UT, dye penetrant, chemical,

stress • New copper end turn was water jet machined from carefully

inspected copper plate material (hardness, SEM) • After extensive qualification tests of the braze technique, the

new end turn was brazed into coil#1 • Inspection

• All the first and second turns of the #1 and #2 coils of all poles were carefully inspected and tested (dye penetrant, in some cases UT and hardness tests)

• One indication of slight porosity was found: end turn replaced

MIT Alternator

• Status • Rotor has successfully passed all electrical tests and

has been reinstalled in the alternator housing on its bearings

• Stator has successfully passed all electrical tests • Flywheel successfully passed UT tests and is ready

to be returned to service • Instrumentation is being reinstalled and calibrations

checked • Alternator operation to resume in mid February

Engineering Systems

• LH Interface Software • New software for FY15 campaign will integrate Coupler

Protection, Transmitter Protection, and Active Control System user interfaces into one interface

• System much easier to use • Some tasks have been automated • UROP student working with an engineer

• LH FFT • Voids in the material limit the obtainable power • It has proved difficult to find a supply of high quality

ferrite material • A new vendor has been found with 10X better specs • Ferrite to Elkonite bonded prototype has reached 125 kW

for 10 s (goal of 200 kW for 5 s) Reactive Bonding

Ferrite to Elkonite Bond

Engineering Systems

• ICRF • Four new enhanced anode FPA tubes on order

(1st tube to ship 02/27/2015, 2nd 03/31/2015) • We are working with PPPL to improve the grid

regulators for the ICRF FPAs • New system installed, tested, and

operational on FMIT#3 • Water cooled system much more reliable • Working with PPPL to complete installation in

FMIT#4 before FY15 campaign begins • The FMIT#4 high voltage power supply will be

upgraded during repair to allow 2.5 MW operation of the transmitter (from 2 MW)

• We have begun preparing the transmitters for FY2015 operation

Reactive Bonding

Grid Regulators

Engineering Systems

• Magnet Power Systems • Spurious signals on the TF supply instrumentation caused early

shutdown of the supply on some shots during the last campaign • Circulating currents caused discharges at cabinet interfaces • Low resistance current paths implemented to eliminate the

discharges • We have begun preparing power systems for FY2015 campaign

MSE Upgrade First of a kind multi-spectral line polarization (MS-LP) MSE system under construction

Measure polarization at 4 wavelengths on same sightline simultaneously Enables wavelength interpolation of partially polarized background, scheme anticipated for ITER MSE Simultaneously detect orthogonally polarized σ and π beam emission ~3x more signal, faster time resolution, less systematic error, more robust error correction

Key enabling technologies: (Mumgaard HTPD invited, Mumgaard APS poster)

Will enable MSE measurements in high power regimes such as H- and I- modes with LHCD Easily taken to other facilities with MSE enabling collaboration, particularly helpful for metal-walled machines

10 Imaging polychromators: 24 High transmission filters: 40 Custom high sensitivity APDs:

Very high throughput: f/# = 0.6 High spectral resolution

Remote control of ovens, APDs

New manufacturer identified ~2x higher than traditional filters

0.7nm FWHM bandpass

Developed with Hamamatsu Modular with large area (5mm diameter)

1/5 the cost of existing APDs

0

20

40

60

80

100

658.5 659 659.5 660 660.5 661

Tran

smis

sion

Wavelength [nm]

MSE Upgrade

• All polychromators assembled and aligned, ovens and detectors complete • Control system complete and tested and ready for integration into MDSplus along with

data acquisition system • Need to upgrade MSE analysis software to handle new hardware • Need to replace existing detectors, terminate fibers and calibrate polarization response

Polychromators and Very Happy Scientists Polychromators Rack Mounted

In-Vessel Work

• Primary goals • Refurbish plasma facing components and diagnostics • Install new advanced divertor diagnostics • Improve power handling capability of the outer divertor • Diagnostic calibration

In-Vessel Work

• Outer divertor modules are being shimmed to provide a small twist in positioning • All outer divertor modules are being

removed, tiles refurbished and shims fitted and modules reinstalled

• Provides a ski-jump to greatly reduce heat flux at the edges of the modules

Button probes being replaced with Rail probes

In-Vessel Work

• New rail probe arrays fabricated for FY2015 campaign • Power flux density has proved

to be too great for standard button probes. They often fail during the campaign

• Rail probes will be much more robust (flush to surface)

• High resolution: from 10 to 21 probe locations

New Rail Probe Arrays

Cables connect to alternate probe

ends

Short Term Schedule

• Planning for 12 weeks of research operation in FY2015

January 22, 2015

• PPPL/MIT 1 yr subcontract was originally signed on January 2, 2014 • Five task areas (~ 6 FTE):

1. Diagnostics for boundary physics research 2. Pedestal physics analysis for NSTX and NSTX-U 3. ECH, EBW, and ICRF heating and current drive physics analyses; plans for RF hardware development 4. Core transport and turbulence physics studies, data analysis, core diagnostics (XICS, LBO, polarimeter, TCI) 5. Non-axisymmetric radiated power diagnostics, 3D magnetic error fields analysis

• Work was placed on hold in light of FY14 budget supporting C-Mod

operations.

• Exception: Task 4.1 - Analysis of high-k scattering data Juan Ruiz Ruiz (Anne White’s MS student) made good progress on thesis work based on analysis of NSTX high-k scattering data. Plan is to continue data analysis into Spring 2015, targeting MS completion in May 2015.

Update on NSTX-U Collaboration Subcontract

January 22, 2015

• PPPL implemented a 1 yr no-cost extension to the subcontract on Dec. 13,

2014 • Tasks were reviewed by MIT/PPPL teams and some minor adjustments to

work plan and personnel were made: 1. Diagnostics for boundary physics research – no change 2. Pedestal physics analysis for NSTX and NSTX-U – scope changed to include NSTX-U experiments; new lead contact (Jerry Hughes) 3. ECH, EBW, and ICRF heating and current drive physics analyses; plans for RF hardware development – removed subtask 3.1b (review of EBW diagnostics); Steve Wukitch sole lead contact 4. Core transport and turbulence physics studies, data analysis, core diagnostics (XICS, LBO, polarimeter, TCI) – no change 5. Non-axisymmetric radiated power diagnostics, 3D magnetic error fields analysis – removed subtask 5.2 (3D error field analysis, experiment planning)

• Subcontract remains mostly on hold at this time due to continued C-Mod

operations in FY15

Update on NSTX-U Collaboration Subcontract

January 22, 2015

• MIT’s 5 year plan (presently under development) will likely carry forward

many elements of the subcontract; many of the subcontract tasks were designed as first-steps toward a longer term collaboration with NSTX-U.

• Continued C-Mod research will accelerate some tasks when subcontract ramps up (example: advanced scanning probe development)

• Dependent on C-Mod operations in FY16 and subsequent ramp-up of a

follow-on five year plan, subcontract tasks and timing for deliverables will likely need to be further modified.

PPPL/MIT will assess this in the March/April time frame

Update on NSTX-U Collaboration Subcontract

DIII-D: Subcontract status and research plans

J. Hughes on behalf of the C-Mod Team

C-Mod Quarterly Review 22 January 2015

GA subcontract for MIT research on DIII-D: Timeline

• 2013: Subcontract negotiations began with intent of funding research in FY14 • 11/2013 – 1/2014: Work was performed under GA-MIT Letter Agreement, while

final subcontract negotiations • 1/2014: Funded collaboration activities put on hiatus following passing of FY14

appropriations • 10/2014: Discussions re-opened on subcontract • 11/2014: MIT and DIII-D research contacts began communicating on potential

projects, key personnel • 11/25/2014: Meeting at PSFC to discuss DIII-D collaboration process, scope • 12/8/2014: Video conference between C-Mod/DIII-D management • Currently:

– Drafts of GA Statement of Work, MIT proposal in progress, based on research topics defined in each area by participants

– MIT proposal will be submitted in response to SoW – Targeting resumption of funded collaboration in March/April 2015

C-Mod/DIII-D Collaboration Status, 22 Jan 2015 1

GA subcontract for MIT research on DIII-D: Scope • Scope reduced from that of previous proposal

– Necessary to allow C-Mod staff to meet other obligations – Spending at reduced rate implies longer life for subcontract – Enables ramp-up of activities over 1—2 years

• Changes in process – Increased participation of students and postdocs, mentored by

MIT scientists and by on-site DIII-D staff – Full-time postdocs to establish on-site presence at DIII-D

• Research in four topical areas is proposed: – Pedestal Physics – Core Transport and Diagnostics – Disruption Warning – RF Physics and Design

C-Mod/DIII-D Collaboration Status, 22 Jan 2015 2

Subcontract work prelude to enhanced DIII-D collaboration • Near-term work is a beginning to larger

collaboration to be defined in MIT 5-year proposal (in development): 9/2015—8/2020

• Themes and topics will align between near-term and long-term proposals, with significant expansion in 5-year plan – Broadened scope in each research – Increased FTEs – Additional PDs, students possible – Increased on-site presence and engagement in DIII-D

experimental program

C-Mod/DIII-D Collaboration Status, 22 Jan 2015 3

International Collab: Development of long-pulse RF actuators and Operational Techniques for High Z PFC

EAST concluded operations before IAEA

Multiple leaks in new tungsten divertor cooling lines were identified and require repair. • Divertor module repair is on critical path for closing the machine.

ICRF coupled 2.7 MW into plasma out of 12 MW possible.

Current plan is to have the machine closed by mid-March. • Dependent on divertor repair.

• Insufficient time to make significant changes to antennas.

Wukitch 1

Summary of Activity: ICRF

The goal for the ICRF group for past EAST campaign was to check out all the systems and maximize coupled power to the plasma.

Power limitation is likely limited due to two major issues: • Antenna toroidal mode spectrum in heating phase (pi phasing) is too high for

target plasmas (3x1019 m-3) - identified by Eric Edlund and Paul Bonoli. ▪ Toroidal mode number is 33 (C-Mod is 10-13). ▪ Cutoff density is ~0.9x1019 m-3 – very low transmission efficiency through

evanescent layer. • Antenna design results in very high mutual coupling and is result of the vacuum

transmission line network. Transmitter operation did not improve with addition of decoupling stubs

and pre-matching. Damage to Faraday screen – fast electrons from disruption or LH? Plan to visit in March to discuss coupling and antenna design. Propose to investigate loading and coupled power as function of density

and antenna phase. • For current drive (π/2) and π/3 phase the toroidal mode numbers are 16 and 11

respectively. Have begun design of new 4-strap field aligned antenna for EAST with

toroidal mode number ~16. Wukitch 2

Summary of Activity: Divertor/Disruptions

We have begun to work with EAST on understanding where divertor leaks are located and investigate a cause. • Developed code to perform

filament reconstruction. • Performing filament

reconstruction to determine contact and eddy currents.

Wukitch 3

• Failure of connection pipes occurred during machine bake out. • Cluster of failures at the interface block may be related to poor electron beam

welds from one of two manufacturers.

Four Chinese visitors are here to review tungsten divertor and discuss plans for hot tungsten divertor.

Plan to perform thermal and electromagnetic analysis to investigate stresses in region of connection pipes and interface block.

Summary of Activity: Disruptions

Integrated filament reconstruction program with MDS trees correct geometry for discharge directly incorporated.

System is live – anyone with linux account can access data and reconstruction. • Critical to engineering studies on divertor electromagnetic studies.

Work on disruptions (Bob Granetz) has been submitted for publication (Chinese Physics B). • Characterization of plasma current quench during disruption in EAST

tokamak • Submitted to Chinese Physics B • Work is based on the disruption database (first sql database at EAST)

implemented by Granetz. • Utilizes MFIL for flux surface reconstruction during disruption (Granetz

contribution).

Bob Granetz visited EAST last fall. Plan to propose experiments on disruptions and runaway electron physics

for upcoming campaign. Wukitch 4

Summary of Activity: Low τP regimes (I-mode)

Videoconference with X. Xu (LLNL), T. Zhang (EAST pedestal group) and Zixi Lui

Prof Gao’s student, Zixi Lui, has started BOUT++ analysis of C-Mod I-modes, in collaboration with X. Xu (LLNL). • MIT supplied equilibrium and pedestal profiles for a well diagnosed, high

confinement discharge.

Lui has nonlinear simulations of C-Mod I-modes, which now seem in quite good agreement with our WCM measurements.

Plan to work with Gao to update our EAST I-mode proposal.

Wukitch 5

International Collaboration on Control and Extension of ITER

and Advanced Scenarios to Long Pulse in EAST and KSTAR

P. T. Bonoli On behalf of the MIT Team:

S. G. Baek, R. S. Granetz, E. Edlund, A. E. Hubbard, Y. Lin, R. R. Parker, M. Porkolab, J. E. Rice, S. Shiraiwa, J. Stillerman,

G. M. Wallace, S. M. Wolfe, and J. C. Wright

DoE Teleconference January 20, 2015

Recent Activities

• Discussions with EAST / KSTAR personnel on performing I-mode

experiments (A. Hubbard).

• Visit by S. Shiraiwa and P. T. Bonoli to EAST in November, 2014.

– Carried out detailed ray tracing / Fokker Planck and full-wave

simulations of LHCD for EAST discharges.

– Detailed discussions with EAST personnel on LHCD experiments

(B. Ding) and theory (N. Xiang).

• Performed off mid-plane LH launcher studies for KSTAR using H-

mode target plasmas (S. Shiraiwa):

– Work carried out for planning purposes at request of Dr. Bae.

• Started development of an ICRF actuator model for EAST for use in

GA TokSys code (E. Edlund & M. Porkolab).

Task 1: Extension of the I-Mode scenario to EAST & KSTAR

• KSTAR (A. Hubbard & J. Ko): – Initial attempts in October, 2014 to produce I-mode were

unsuccessful due to problems with position control in USN configuration (drsep and inner gap):

– Will try again in 2015 when KSTAR starts up. • EAST (A. Hubbard, Prof. X. Gao, and T. Zhang):

– I-mode investigation and parameter space expansion on EAST will be highlighted in the upcoming run campaign under research topic P3 (“Other physical issues essential for efficient exploitation of EAST and CFETR”).

• IAEA: – Published/presented joint ITPA paper and poster on I-mode

studies. – Paper highlighted the field dependence of experiments on C-Mod,

which were largely motivated by collaborations with lower Bt devices.

Task 3: Analysis of LHCD experiments in EAST (S. Shiraiwa, P. Bonoli, B. Ding, M. Li, J. C. Wright, C. Yang)

• Carried out LHCD simulations for EAST discharge #48888 at 5.5s using GENRAY/CQL3D and πScope for workflow: – Expt. maintained 370 kA using 2 MW of 4.6 GHz LH power. – “Standard” simulation gives LH driven current profile that is too

hollow relative to expt. and total LHCD current is too high (570kA).

– Found that by combining radial diffusion with a small level of spectral broadening both the total LHCD current and HXR/current profile shapes can be reproduced in the simulation, with N||ext = 2.7 (5% of main lobe at N|| = 2.05) + χfast = 0.3 m2/s.

• Carried out full-wave TorLH simulations for discharge #488888: – 4095 poloidal modes and 480 radial elements were needed to

converge simulation because of large size of EAST device.. – Done at NERSC using 32,256 cores for ~7.5 hours.

EAST Target discharge (#48888, 5.5s)

Radial diffusion + small level of spectral broadening improves comparison with experimental HXR profiles

Note1 : HXR synthetic diagnostics is uncalibrated. Do not compare the count rate (yet). Note2 : Shift of peak emission is due to fabrication error in diagnostic.

HXR – GENRAY / CQL3D

N||ext = 2.7 N||ext = 2.5

Radial diffusion + small level of spectral broadening also improves comparison with total current density inferred

from EFIT reconstructions.

Experimental J||(0) from EFIT reconstruction is ~ 1.2 MA / cm2.

Thus far, N||ext = 2.7 (5% of main lobe at N|| = 2.05) + χfast = 0.3 m/s2 gives best results.

Activities for Near Term • Continue planning / preparation for I-mode experiments in EAST

and re-visit experiments in KSTAR (A. Hubbard). • Continue ray tracing / Fokker Planck and full-wave analysis of

LHCD experiments in EAST (P. Bonoli, S. Shiraiwa, J. Wright). • Participate in LHCD experiments on EAST:

– Perform experiments to examine source frequency dependence of LHCD (2.45 GHz vs. 4.6 GHz) as a function of density by monitoring PDI and hard x-ray emission (S. Baek, R. Parker).

– Study poloidal dependence of LHCD by separately powering off mid-plane rows of 4.6 GHz LH launcher (R. Parker, G. Wallace).

• ICRF actuator simulations using the TORIC solver to understand optimal coupling / absorption regimes in EAST (Edlund, Porkolab, Wukitch): – Will also provide a reduced ICRF actuator model for the GA TokSys

code. • Continue to support advanced LHRF launcher concepts (high field

side and off-midplane) for EAST and KSTAR using GENRAY / CQL3D (S. Shiraiwa, P. Bonoli).