+--------------------+----------------------+-------+-----------------+
| **Princeton Plasma |                      |       |                 |
| Physics            |                      |       |                 |
| Laboratory**       |                      |       |                 |
|                    |                      |       |                 |
| **NSTX             |                      |       |                 |
| Experimental       |                      |       |                 |
| Proposal**         |                      |       |                 |
+--------------------+----------------------+-------+-----------------+
| **Title:           |                      |       |                 |
| Comparative Study  |                      |       |                 |
| of the scattered   |                      |       |                 |
| spectra between L  |                      |       |                 |
| and H mode         |                      |       |                 |
| confinement regime |                      |       |                 |
| on NSTX.**         |                      |       |                 |
+--------------------+----------------------+-------+-----------------+
| **OP-XP-629**      | > **Revision: 0**    | >     |                 |
|                    |                      |  Effe |                 |
|                    |                      | ctive |                 |
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|                    |                      | Date: |                 |
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|                    |                      | > *   |                 |
|                    |                      | (Ref. |                 |
|                    |                      | >     |                 |
|                    |                      | OP-AD |                 |
|                    |                      | -97)* |                 |
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|                    |                      | >     |                 |
|                    |                      | Expir |                 |
|                    |                      | ation |                 |
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|                    |                      | Date: |                 |
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|                    |                      |  yrs. |                 |
|                    |                      | > u   |                 |
|                    |                      | nless |                 |
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|                    |                      | > st  |                 |
|                    |                      | ipula |                 |
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+--------------------+----------------------+-------+-----------------+
| **PROPOSAL         |                      |       |                 |
| APPROVALS**        |                      |       |                 |
+--------------------+----------------------+-------+-----------------+
| **Author: Hyeon    |                      |       | > Date          |
| Park, Dave Smith,  |                      |       |                 |
| E. Mazzucato.**    |                      |       |                 |
+--------------------+----------------------+-------+-----------------+
| **ATI -- ET Group  |                      |       | > Date          |
| Leader: M. Bell,   |                      |       |                 |
| K. Kitz (T&T)**    |                      |       |                 |
+--------------------+----------------------+-------+-----------------+
| **RLM - Run        |                      |       | > Date          |
| Coordinator: R.    |                      |       |                 |
| Raman**            |                      |       |                 |
+--------------------+----------------------+-------+-----------------+
| **Responsible      |                      |       |                 |
| Division:          |                      |       |                 |
| Experimental       |                      |       |                 |
| Research           |                      |       |                 |
| Operations**       |                      |       |                 |
+--------------------+----------------------+-------+-----------------+
| [**Chit Review     |                      |       |                 |
| Board**            |                      |       |                 |
| (designated by Run |                      |       |                 |
| Coordin            |                      |       |                 |
| ator)]{.underline} |                      |       |                 |
+--------------------+----------------------+-------+-----------------+
| **MINOR            |                      |       |                 |
| MODIFICATIONS**    |                      |       |                 |
| (Approved by       |                      |       |                 |
| Experimental       |                      |       |                 |
| Research           |                      |       |                 |
| Operations)        |                      |       |                 |
+--------------------+----------------------+-------+-----------------+
|                    |                      |       |                 |
+--------------------+----------------------+-------+-----------------+

NSTX EXPERIMENTAL PROPOSAL

Error: Reference source not found: Comparative Study of the scattered
spectra between L and H mode confinement regime on NSTX. OP-XP-629

# 1. Overview of planned experiment 

During the initial operation of the high-k scattering system on NSTX,
the observed scattered power spectra during the H-mode phase was
significantly different from the L-mode phase at the edge of the plasma.
Monotonically decreasing power spectra as function of wave-numbers
during the L-mode phase is changed into a non-monotonic shape. A growth
of the power spectrum at the highest k was noted as the power spectra of
intermediate wave-numbers were remained clamped. The observed phenomenon
is new and requires a systematic study near the edge region and the
measurement will be compared with other fluctuation measurement and
timing of the transition. The objective of this XP is to measure the
scattered spectra at a few different edge radial positions (143 cm. 140
cm and 137 cm) so that the detailed comparison studies with fluctuation
diagnostics and variations of the transition characteristics at
different tangencies where the pressure gradient is changing rapidly.

# 2. Theoretical/ empirical justification

> 1\) The newly observed variations in the scattered spectra from L-mode
> to the H-mode phase transition warrant the detailed experiment to
> improve understanding of the relationship between confinement and the
> behaviors of the turbulence at high wavenumbers.
>
> 2\) The observed momentum bifurcation from one wave-number to another
> may require more experiments to build new theoretical model.
>
> 3\) Understanding of the spatial delay time of the changes in the
> power spectra at different wave-numbers during L to H transition is
> critical to build a model. Therefore, comparison studies of the
> transition timing and variation in the scattered spectra as function
> of tangencies with other fast fluctuation diagnostics. The transition
> time changes can be compared with the D signals, Mirnov, etc.

# 3. Experimental run plan

> Sample scattering raw signals from the edge of the OH and NBI heated
> are illustrated in Fig. 1 and Fig. 2, respectively. In an OH
> discharge, the scattered power is monotonically decreasing as function
> of wavenumbers within the present experimental error bars. The trend
> in L-mode discharge of the NBI heated plasmas is not much different
> from that of the OH discharges as shown in early and later stages of
> the discharge in Fig. 2. During H-mode phase, changes in the scattered
> spectra are significantly different from those of the L-mode phase as
> illustrated in this figure. As the transition is occurring, a sudden
> drop of the scattered power in lower wave-numbers is clear as it has
> been predicted in many other experiments. However, the recovery of the
> scattered power in the lowest wavenumber is noted while the power
> spectra in the intermediate wavenumbers are clamped for the duration
> of the H--mode. Notable growth of power spectra is observed at the
> highest wave-number. The new observation certainly warrants more
> experiment to clarify the physics of high-k spectra behavior during
> H-mode phase on NSTX. The model discharge is shot #119284, where L to
> H mode transition is clear and scattering system was tested and
> changes in scattered spectra during L to H mode phase was made.
>
> ![](media/image1.jpeg){width="4.557638888888889in"
> height="3.4694444444444446in"}
>
> Fig. 1. Scattered geometry and raw scattered signals at five different
> wavenumbers of the OH discharge.
>
> ![](media/image2.jpeg){width="4.638888888888889in"
> height="3.4006944444444445in"}
>
> Fig. 2. Scattered raw signal at five different wavenumbers from NBI
> heated plasmas where L/H transition and corresponding changes in
> scattered power spectra are clear.
>
> a\) Stear the launching beam for the Rt =143 cm and adjust the five
> collection mirrors accordingly. Two discharges for this set are
> required.
>
> b\) Reteat step a) at Rt = 140 cm
>
> c\) Repeat step a) at Rt = 137 cm

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

> NBI \~2 MW is required with the source combination for the Ti
> measurement (source A mandatory for Ti measurement). Reflectometry,
> probe, GPI and other fluctuation diagnostics systems are required, if
> possible.

# 5. Planned analysis

> a\) Scattered signals will be calibrated with the attenuators (optical
> and electrical) and theoretical numbers for the scattering geometry
> such as interaction length will be folded to plot scattered power as
> function of wave-numbers. FFT analysis will provide frequency spectra
> information.
>
> b\) EFIT and TRANSP will be required for the flux surface check and
> transport analysis (~I~, ~e~ and other transport related plasma
> parameters)

# 6. Planned publication of results

With the system calibration after the run and TRANSP analysis, the
result will be aimed to be published in PRL.

PHYSICS OPERATIONS REQUEST

Error: Reference source not found: Comparative Study of the scattered
spectra between L and H mode confinement regime on NSTX. OP-XP-629

Machine conditions (specify ranges as appropriate)

> I~TF~ (kA): **-55 kA** Flattop start/stop (s): **0.0/0.8**

I~P~ (MA): **800 kA** Flattop start/stop (s): **0.15/0.6**

Configuration: **Inner Wall / Lower Single Null / Upper SN / Double
Null**

> Outer gap (m): **\_\_\_\_\_**, Inner gap (m): **\_\_\_\_\_**
>
> Elongation : **\_\_\_\_\_**, Triangularity : **\_\_\_\_\_**
>
> Z position (m): **0.00 SAME CONFIGURATION with #119284**
>
> Gas Species: **D**, Injector: **Midplane / Inner wall / Lower Dome**
>
> NBI - Species: **D**, Sources: **A/C**, Voltage (kV): **80kV**,
> Duration (s): **01/0.55**

ICRF -- Power (MW): **\_\_\_\_**, Phasing: **Heating / CD**, Duration
(s): **\_\_\_\_\_**

CHI: **On / Off**

*Either:* List previous shot numbers for setup: **#119284**

*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

Error: Reference source not found: Comp. Study of the scatt. spectra
between L/H mode conf. regime on NSTX.

OP_XP-629

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