+--------------------+----------------------+-------+-----------------+
| **Princeton Plasma |                      |       |                 |
| Physics            |                      |       |                 |
| Laboratory**       |                      |       |                 |
|                    |                      |       |                 |
| **NSTX             |                      |       |                 |
| Experimental       |                      |       |                 |
| Proposal**         |                      |       |                 |
+--------------------+----------------------+-------+-----------------+
| **Title:**         |                      |       |                 |
| Stability limits   |                      |       |                 |
| with strong        |                      |       |                 |
| shaping at high    |                      |       |                 |
| I~N~               |                      |       |                 |
+--------------------+----------------------+-------+-----------------+
| **OP-XP-727**      | > **Revision:**      | >     |                 |
|                    |                      |  Effe |                 |
|                    |                      | ctive |                 |
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|                    |                      | Date: |                 |
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|                    |                      | (Ref. |                 |
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|                    |                      | OP-AD |                 |
|                    |                      | -97)* |                 |
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|                    |                      | Expir |                 |
|                    |                      | ation |                 |
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|                    |                      | Date: |                 |
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+--------------------+----------------------+-------+-----------------+
| **PROPOSAL         |                      |       |                 |
| APPROVALS**        |                      |       |                 |
+--------------------+----------------------+-------+-----------------+
| **Author: D.       |                      |       | > Date 5/2/07   |
| Gates**            |                      |       |                 |
+--------------------+----------------------+-------+-----------------+
| **ATI -- ET Group  |                      |       | > Date          |
| Leader: S.         |                      |       |                 |
| Sabbagh/N.         |                      |       |                 |
| Gorelenkov**       |                      |       |                 |
+--------------------+----------------------+-------+-----------------+
| **RLM - Run        |                      |       | > Date          |
| Coordinator: D.    |                      |       |                 |
| Gates/ M. Bell     |                      |       |                 |
| (Deputy)**         |                      |       |                 |
+--------------------+----------------------+-------+-----------------+
| **Responsible      |                      |       |                 |
| Division:          |                      |       |                 |
| Experimental       |                      |       |                 |
| Research           |                      |       |                 |
| Operations**       |                      |       |                 |
+--------------------+----------------------+-------+-----------------+
| [**Chit Review     |                      |       |                 |
| Board**            |                      |       |                 |
| (designated by Run |                      |       |                 |
| Coordin            |                      |       |                 |
| ator)]{.underline} |                      |       |                 |
+--------------------+----------------------+-------+-----------------+
| **MINOR            |                      |       |                 |
| MODIFICATIONS**    |                      |       |                 |
| (Approved by       |                      |       |                 |
| Experimental       |                      |       |                 |
| Research           |                      |       |                 |
| Operations)        |                      |       |                 |
+--------------------+----------------------+-------+-----------------+
|                    |                      |       |                 |
+--------------------+----------------------+-------+-----------------+

NSTX EXPERIMENTAL PROPOSAL

OP-XP-727

# 1. Overview of planned experiment 

The goal is to develop high current plasmas at low toroidal field and
strong heating to investigate the β-limits as a function of shaping in
the low q\* regime. This continues work done in 2005 and is motivated by
the modification to the PF1A coil.

# 2. Theoretical/ empirical justification

> ![](media/image1.png){width="6.583333333333333in"
> height="4.256944444444445in"}This experiment is the most recent in a
> series of experiments designed to investigate the performance of
> highly shaped double null plasmas. Experience from 2005 indicates that
> high elongation and high triangularity operation is capable of
> supporting interesting plasma performance regimes. Stability
> calculations made the NSTX 5-year plan indicate that plasmas with
> simultaneous high elongation and triangularity have higher β-limits,
> and simple geometric arguments also argue they should support higher
> plasma current due to increased q\* for the same plasma current.

# 3. Experimental run plan

> 1\. Reload fiducial, reduce TF to 3kGauss. Use lithium evaporator at
> nominal rate of 25mg/minute. Evaporate into 7 minute glow with \~15
> minute rep rate.
>
> 2\. Decrease PF1AU to 0.5\*nominal value for fiducial in steps of 25%.
> Increase upper and lower outer squareness to achieve kappa = 2.5 with
> 1cm drsep. Require 12cm outer gap and 6cm inner gap.
>
> If necessary adjust Ip ramp rate and PF1A time history, drsep time
> history, and beam timing to permit successful ramp-up. (5-15 shots)
>
> 3\. Increase current in steps of 100kA maintaining ramp rate after
> knee in Ip ramp, maintaining best Ip ramp rate. If plasma appears
> power limited consider increasing voltage on source C to 95kV. (5-10
> shots)
>
> 4\. Repeat best shots at 3.5kGauss in attempt to create scenario with
> \~35% *β~t~* for \~2*τ~E~* (4-5shots)

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

> Reliable high power NBI is a prerequisite. Thomson is required. CHERS
> and MSE are highly desirable. Lithium evaporation is required.

# 5. Planned analysis

> EFIT is required. TRANSP will be run on select shots according to data
> availability. TSC analysis is a possibility. Time dependent DCON
> analysis will be run on select shots.

# 6. Planned publication of results

If successful in increasing *β* substantially, would publish the results
in Physical Review Letters. Otherwise the material would be sent to
Phys. Plasmas.

PHYSICS OPERATIONS REQUEST

OP-XP-727

Machine conditions (specify ranges as appropriate)

> I~TF~ (kA): **36kA-54kA** Flattop start/stop (s): **N/A**

I~P~ (MA): **1.0 - 1.5MA** Flattop start/stop (s): **N/A**

Configuration: **Double Null**

> Outer gap (m): **10cm**, Inner gap (m): **2-4cm**
>
> Elongation : \~**2.5**, Triangularity : **0.8**
>
> Z position (m): **0.00**
>
> Gas Species: **D**, Injector: **Midplane CS gas valve**
>
> NBI - Species: **D**, Sources: **A/B/C**, Voltage (kV): **90kV**,
> Duration (s): **400ms**

ICRF -- Power (MW): **None**, Phasing: **N/A**, Duration (s): **N/A**

CHI: **Off**

*Either:* List previous shot numbers for setup: **fiducial**

*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

OP-XP-727

+----------------------+----+-----+-----------------------------------+
| #### Diagnostic      | #  | ##  | #### Instructions                 |
|                      | ## | ##  |                                   |
|                      | #  | Des |                                   |
|                      | Ne | ire |                                   |
|                      | ed |     |                                   |
+----------------------+----+-----+-----------------------------------+
| > Bolometer --       |    |     |                                   |
| > tangential array   |    |     |                                   |
+----------------------+----+-----+-----------------------------------+
| > Bolometer array -  |    |     |                                   |
| > divertor           |    |     |                                   |
+----------------------+----+-----+-----------------------------------+
| > CHERS              |    |     |                                   |
+----------------------+----+-----+-----------------------------------+
| > Divertor fast      |    |     |                                   |
| > camera             |    |     |                                   |
+----------------------+----+-----+-----------------------------------+
| > Dust detector      |    |     |                                   |
+----------------------+----+-----+-----------------------------------+
| > EBW radiometers    |    |     |                                   |
+----------------------+----+-----+-----------------------------------+
| > Edge deposition    |    |     |                                   |
| > monitor            |    |     |                                   |
+----------------------+----+-----+-----------------------------------+
| > Edge pressure      |    |     |                                   |
| > gauges             |    |     |                                   |
+----------------------+----+-----+-----------------------------------+
| > Edge rotation      |    |     |                                   |
| > spectroscopy       |    |     |                                   |
+----------------------+----+-----+-----------------------------------+
| > Fast lost ion      |    |     |                                   |
| > probes - IFLIP     |    |     |                                   |
+----------------------+----+-----+-----------------------------------+
| > Fast lost ion      |    |     |                                   |
| > probes - SFLIP     |    |     |                                   |
+----------------------+----+-----+-----------------------------------+
| > Filtered 1D        |    |     |                                   |
| > cameras            |    |     |                                   |
+----------------------+----+-----+-----------------------------------+
| > Filterscopes       |    |     |                                   |
+----------------------+----+-----+-----------------------------------+
| > FIReTIP            |    |     |                                   |
+----------------------+----+-----+-----------------------------------+
| > Gas puff imaging   |    |     |                                   |
+----------------------+----+-----+-----------------------------------+
| > Infrared cameras   |    |     |                                   |
+----------------------+----+-----+-----------------------------------+
| > Interferometer - 1 |    |     |                                   |
| > mm                 |    |     |                                   |
+----------------------+----+-----+-----------------------------------+
| > Langmuir probe     |    |     |                                   |
| > array              |    |     |                                   |
+----------------------+----+-----+-----------------------------------+
| > Magnetics -        |    |     |                                   |
| > Diamagnetism       |    |     |                                   |
+----------------------+----+-----+-----------------------------------+
| > Magnetics - Flux   |    |     |                                   |
| > loops              |    |     |                                   |
+----------------------+----+-----+-----------------------------------+
| > Magnetics - Locked |    |     |                                   |
| > modes              |    |     |                                   |
+----------------------+----+-----+-----------------------------------+
| > Magnetics - Pickup |    |     |                                   |
| > coils              |    |     |                                   |
+----------------------+----+-----+-----------------------------------+
| > Magnetics -        |    |     |                                   |
| > Rogowski coils     |    |     |                                   |
+----------------------+----+-----+-----------------------------------+
| > Magnetics - RWM    |    |     |                                   |
| > sensors            |    |     |                                   |
+----------------------+----+-----+-----------------------------------+
| > Mirnov coils --    |    |     |                                   |
| > high frequency     |    |     |                                   |
+----------------------+----+-----+-----------------------------------+
| > Mirnov coils --    |    |     |                                   |
| > poloidal array     |    |     |                                   |
+----------------------+----+-----+-----------------------------------+
| > Mirnov coils --    |    |     |                                   |
| > toroidal array     |    |     |                                   |
+----------------------+----+-----+-----------------------------------+
| > MSE                |    |     |                                   |
+----------------------+----+-----+-----------------------------------+
| > Neutral particle   |    |     |                                   |
| > analyzer           |    |     |                                   |
+----------------------+----+-----+-----------------------------------+
| > Neutron            |    |     |                                   |
| > measurements       |    |     |                                   |
+----------------------+----+-----+-----------------------------------+
| > Plasma TV          |    |     |                                   |
+----------------------+----+-----+-----------------------------------+
| > Reciprocating      |    |     |                                   |
| > probe              |    |     |                                   |
+----------------------+----+-----+-----------------------------------+
| > Reflectometer --   |    |     |                                   |
| > core               |    |     |                                   |
+----------------------+----+-----+-----------------------------------+
| > Reflectometer -    |    |     |                                   |
| > SOL                |    |     |                                   |
+----------------------+----+-----+-----------------------------------+
| > RF antenna camera  |    |     |                                   |
+----------------------+----+-----+-----------------------------------+
| > RF antenna probe   |    |     |                                   |
+----------------------+----+-----+-----------------------------------+
| > SPRED              |    |     |                                   |
+----------------------+----+-----+-----------------------------------+
| > Thomson scattering |    |     |                                   |
+----------------------+----+-----+-----------------------------------+
| > Ultrasoft X-ray    |    |     |                                   |
| > arrays             |    |     |                                   |
+----------------------+----+-----+-----------------------------------+
| > Visible            |    |     |                                   |
| > bremsstrahlung     |    |     |                                   |
| > det.               |    |     |                                   |
+----------------------+----+-----+-----------------------------------+
| > Visible            |    |     |                                   |
| > spectrometers      |    |     |                                   |
| > (VIPS)             |    |     |                                   |
+----------------------+----+-----+-----------------------------------+
| > X-ray crystal      |    |     |                                   |
| > spectrometer - H   |    |     |                                   |
+----------------------+----+-----+-----------------------------------+
| > X-ray crystal      |    |     |                                   |
| > spectrometer - V   |    |     |                                   |
+----------------------+----+-----+-----------------------------------+
| > X-ray PIXCS (GEM)  |    |     |                                   |
| > camera             |    |     |                                   |
+----------------------+----+-----+-----------------------------------+
| > X-ray pinhole      |    |     |                                   |
| > camera             |    |     |                                   |
+----------------------+----+-----+-----------------------------------+
| > X-ray TG           |    |     |                                   |
| > spectrometer       |    |     |                                   |
+----------------------+----+-----+-----------------------------------+