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| Proposal**         |                      |       |                 |
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| Title: ELM         |                      |       |                 |
| characterization   |                      |       |                 |
| in NSTX            |                      |       |                 |
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| **PROPOSAL         |                      |       |                 |
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| **Responsible      |                      |       | > Date 06/04/07 |
| Author: R.         |                      |       |                 |
| Maqueda**          |                      |       |                 |
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| **ATI -- ET Group  |                      |       | > Date          |
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NSTX EXPERIMENTAL PROPOSAL

TITLE: ELM characterization in NSTX No. **OP-XP-746**

AUTHOR: **R. Maqueda, et al.** DATE: **06/04/07**

# 1. Overview of planned experiment 

> Edge Localized Modes (ELMs) are present during routine operation of
> NSTX with 3 different types observed: Type I, Type III and Type V.
> These modes are born at the H-mode pedestal, grow through linear and
> non-linear phases, evolve into filamentary structures and, finally,
> propagate both poloidally and radially in the SOL until they reach the
> plasma facing components. The ELMs are also characterized by a short
> period of increased turbulent and blob activity following the initial
> mode growth. The goal of this XP is to measure all phases of the ELM,
> as briefly described above, for all 3 types of ELMs. All relevant
> diagnostics available in NSTX will be used in this effort.

# 2. Theoretical/ empirical justification

> The ELMs present during H-mode operation of tokamak devices evolve
> into filamentary structures that propagate radially out in the SOL and
> result on short-time, localized deposition of energy and particles on
> plasma facing components. This is an ITER-relevant concern and is,
> consequently, of great interest in the community (see Refs. 1-9 and
> references within). NSTX diagnostics, including visible fast-imaging,
> are very well suited to substantially contribute in this subject.
>
> This experiment will reproduce all 3 ELM types routinely seen in NSTX
> and diagnose their evolution, from the initial growth phase, through
> the non-linear coalescence into filaments, and into filament
> propagation in the SOL.
>
> In addition, the ELM is followed by a short period of increased
> turbulent and blob activity. A potential candidate for the origin of
> this activity is the perturbed field lines associated with the ELM and
> a redution (or loss) of the electric field well,^10^ a characteristic
> of the H-mode. This leads to additional particles and energy losses
> that in the MAST device have been measured to account for 50%-70% of
> the ELM losses. (The filaments themselves account for the rest.) This
> transient increase in turbulence will be also studied.
>
> For these purposes the following diagnostics will be used:

-   Visible fast-imaging (wide angle, gas puff imaging and divertor).

-   USXR arrays with different filters and thicknesses.

-   FIReTIP chords.

-   Fast scanning probe.

-   Divertor probes, filterscopes and 1-D cameras.

-   30-point Thomson scattering (for stability analysis).

-   UCLA reflectometer, possibly ORNL's edge reflectometer.

-   Fast Mirnov arrays.

> \_\_\_\_\_\_\_\_\_\_\_\_\_
>
> 1\. W. Fundamenski, et al., Plasma Phys. Control. Fusion 46 (2004)
> 233.
>
> 2\. J. Boedo, et al., Phys. Plasmas 12 (2005) #072516.
>
> 3\. B. Kurzan, et al., Phys. Rev. Lett. (2005) #145001.
>
> 4\. A. Kirk, et al., Phys. Rev .Lett. 96 (2006) #185001.
>
> 5\. G. Antar, et al., Phys. Plasmas 13 (2006) #082503.
>
> 6\. A. Kirk, et al., Plasma Phys. Control. Fusion 48 (2006) B433.
>
> 7\. J. Terry, et al., J. Nuclear Mater. 363-365 (2007) 994.
>
> 8\. R. Maqueda, et al., J. Nuclear Mater. 363-365 (2007) 1000.
>
> 9\. B. Kock, et al., J. Nuclear Mater. 363-365 (2007) 1056
>
> 10\. M. Wade, et al., Phys. Rev. Lett. 94 (2005) #225001.

# 3. Experimental run plan

> This XP will reproduce shots taken in the very recent past
> (post-Liter) and repeat them to allow diagnostic settings to be
> changed:
>
> **1)** Type I ELM: Reproduce shot 124364 (5 shots).
>
> **2)** Type III ELM: Reproduce shot 124374 (5 shots).
>
> **3)** Type V ELM: Reproduce shot 124635 (5 shots).
>
> **Total: 15 shots.**
>
> [Note]{.underline}: In case that the desired ELMs are not obtained,
> multiple variations can be tried: fuelling, beam power, elongation,
> use of SPAs, etc. Options will be consulted with machine operators and
> colleagues having intimate knowledge of the options available.
>
> For each of the 5 shots reproduced for each ELM Type the filters on
> the USXR arrays will be changed as follows:

  --------------- ---------------------------- --------------------------
  **Shot**        **Hup**                      **Hdown**

  1               Be 100m                      Be 10m

  2               Be 10m                       Be 10m

  3               Be 5m                        Be 10m

  4               Be 5m                        Be 5m

  5               Pinhole                      Be 5m
  --------------- ---------------------------- --------------------------

> The fast scanning probe will be inserted to increasing depths during
> these 5 shots until problems are encountered and then fixed "one step
> back" for the rest of the shots. Probe timing will be kept fixed for
> each particular shot (i.e., ELM Type) to match the timing of the GPI
> puff (see below).
>
> The Gas Puff Imaging D~2~ puff will be triggered at the following
> times:
>
> Type I ELMs, shot 124365: 350 ms.
>
> Type III ELMs, shot 124373: 290 ms.
>
> Type IV ELMs, shot 124635: 300 ms

# 4. Required machine, NBI, RF, CHI and diagnostic capabilities

All 3 sources of NBI. See diagnostics table for diagnostics required.

# 5. Planned analysis

This XP will gather data from multiple diagnostics to characterize the
mode structure of the ELM, its evolution into edge/SOL filaments and the
propagation of such filaments in the SOL.

EFIT/LRDFIT needed.

Data will also be provided for stability evaluation.

# 6. Planned publication of results

If successful, results will be submitted to appropriate journal.

PHYSICS OPERATIONS REQUEST

Title: ELM characterization in NSTX OP-XP-746

Machine conditions (specify ranges as appropriate)

> I~TF~ (kA): **4.5 kG** Flattop start/stop (s): **\***

I~P~ (MA): **0.8 MA** Flattop start/stop (s): **\***

Configuration:

> Outer gap (m): **\*** Inner gap (m): **\***
>
> Elongation : **\*** Triangularity : **\***
>
> Z position (m): **\***
>
> Gas Species: **D2** Injector(s): HFS
>
> NBI - Species: **D** Sources: **all** Voltage (kV): **2 MW ea**
> Duration (s): **\***

ICRF -- Power (MW): **no** Phasing: n.a. Duration (s): n.a.

CHI: **no**

*Either:* List previous shot numbers for setup: **(\*) 124364, 124374,
124635**

*Or:* Sketch the desired time profiles, including inner and outer gaps,
, , heating, fuelling, etc. as appropriate. Accurately label the sketch
with times and values.

DIAGNOSTIC CHECKLIST

Title: ELM characterization in NSTX OP-XP-746

  -------------------------------------------------------------------------------
  **Diagnostic**             **Need**   **Desire**   **Instructions**
  -------------------------- ---------- ------------ ----------------------------
  Bolometer -- tangential               **X**        
  array                                              

  Bolometer -- divertor                 **X**        

  CHERS -- toroidal                     **X**        

  CHERS -- poloidal                     **X**        

  Divertor fast camera                  **X**        

  Dust detector                                      

  EBW radiometers                                    

  Edge deposition monitors                           

  Edge pressure gauges                               

  Edge rotation diagnostic   **X**                   

  Fast ion D_alpha - FIDA               **X**        

  Fast lost ion probes -                             
  IFLIP                                              

  Fast lost ion probes -                             
  SFLIP                                              

  Filterscopes               **X**                   

  FIReTIP                    **X**                   

  Gas puff imaging           **X**                   

  H camera - 1D                         **X**        

  High-k scattering                                  

  Infrared cameras                      **X**        

  Interferometer - 1 mm                              

  Langmuir probes - divertor **X**                   

  Langmuir probes -- RF                              
  antenna                                            

  Magnetics -- Diamagnetism  **X**                   

  Magnetics - Flux loops     **X**                   

  Magnetics - Locked modes   **X**                   

  Magnetics - Pickup coils   **X**                   

  Magnetics - Rogowski coils **X**                   

  Magnetics - RWM sensors               **X**        

  Mirnov coils -- high       **X**                   
  frequency                                          

  Mirnov coils -- poloidal   **X**                   
  array                                              

  Mirnov coils -- toroidal   **X**                   
  array                                              

  MSE                                   **X**        

  NPA -- ExB scanning                                

  NPA -- solid state                                 

  Neutron measurements                               

  Plasma TV                  **X**                   With Phantom 7 camera

  Reciprocating probe        **X**                   

  Reflectometer -- 65GHz     **X**                   

  Reflectometer --                      **X**        
  correlation                                        

  Reflectometer -- FM/CW                             

  Reflectometer -- fixed f                           

  Reflectometer -- SOL                  **X**        

  RF edge probes                                     

  Spectrometer -- SPRED                 **X**        

  Spectrometer -- VIPS                  **X**        

  SWIFT -- 2D flow                                   

  Thomson scattering         **X**                   

  Ultrasoft X-ray arrays     **X**                   

  Ultrasoft X-ray arrays --                          
  bicolor                                            

  Ultrasoft X-rays -- TG                             
  spectr.                                            

  Visible bremsstrahlung                             
  det.                                               

  X-ray crystal                                      
  spectrometer - H                                   

  X-ray crystal                                      
  spectrometer - V                                   

  X-ray fast pinhole camera                          
  -------------------------------------------------------------------------------