+--------------------+----------------------+-------+-----------------+
| **Princeton Plasma |                      |       |                 |
| Physics            |                      |       |                 |
| Laboratory**       |                      |       |                 |
|                    |                      |       |                 |
| **NSTX             |                      |       |                 |
| Experimental       |                      |       |                 |
| Proposal**         |                      |       |                 |
+--------------------+----------------------+-------+-----------------+
| **Title: HHFW      |                      |       |                 |
| Power Balance vs B |                      |       |                 |
| at Constant q**    |                      |       |                 |
+--------------------+----------------------+-------+-----------------+
| **OP-XP-617**      | > **Revision:**      | >     |                 |
|                    |                      |  Effe |                 |
|                    |                      | ctive |                 |
|                    |                      | >     |                 |
|                    |                      | Date: |                 |
|                    |                      | > Feb |                 |
|                    |                      | > 14, |                 |
|                    |                      | >     |                 |
|                    |                      |  2006 |                 |
|                    |                      | >     |                 |
|                    |                      | > *   |                 |
|                    |                      | (Ref. |                 |
|                    |                      | >     |                 |
|                    |                      | OP-AD |                 |
|                    |                      | -97)* |                 |
|                    |                      | >     |                 |
|                    |                      | >     |                 |
|                    |                      | Expir |                 |
|                    |                      | ation |                 |
|                    |                      | >     |                 |
|                    |                      | Date: |                 |
|                    |                      | > Feb |                 |
|                    |                      | > 14, |                 |
|                    |                      | >     |                 |
|                    |                      |  2008 |                 |
|                    |                      | >     |                 |
|                    |                      | > *(2 |                 |
|                    |                      | >     |                 |
|                    |                      |  yrs. |                 |
|                    |                      | > u   |                 |
|                    |                      | nless |                 |
|                    |                      | >     |                 |
|                    |                      |  othe |                 |
|                    |                      | rwise |                 |
|                    |                      | > st  |                 |
|                    |                      | ipula |                 |
|                    |                      | ted)* |                 |
+--------------------+----------------------+-------+-----------------+
| **PROPOSAL         |                      |       |                 |
| APPROVALS**        |                      |       |                 |
+--------------------+----------------------+-------+-----------------+
| **Author: J.       |                      |       | > Date          |
| Hosea, R. Bell, S. |                      |       |                 |
| Bernabei, B.       |                      |       |                 |
| LeBlanc, C.K.      |                      |       |                 |
| Phillips, P. Ryan, |                      |       |                 |
| D. Stutman, J.     |                      |       |                 |
| Wilgen, J.R.       |                      |       |                 |
| Wilson, et al.**   |                      |       |                 |
+--------------------+----------------------+-------+-----------------+
| **ATI -- ET Group  |                      |       | > Date          |
| Leader: Gary       |                      |       |                 |
| Taylor**           |                      |       |                 |
+--------------------+----------------------+-------+-----------------+
| **RLM - Run        |                      |       | > Date          |
| Coordinator: Roger |                      |       |                 |
| 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

Title: HHFW Power Balance vs B at Constant q OP-XP-617

# 1. Overview of planned experiment 

> **Goal: Measure RF power loss properties as a function of magnetic
> field constant q to elucidate:**
>
> • RF power loss scaling with B under similar stability conditions
>
> • PDI ion heating loss vs B
>
> • Fast wave propagation characteristic effects on surface wave
> propagation and damping

# 2. Theoretical/ empirical justification

> A summary of the justification of this experiment is that it should
> provide data that can be analyzed to support the hypothesis that
> higher magnetic field should give higher efficiency of heating/current
> drive for a given wave-number launched by the antenna. Primarily:

• PDI instability should be weaker at higher field

> • Onset density for propagation of HHFW is approximately proportional
> to B at a given k~\|\|~ -
>
> waves are propagating farther from plasma edge at higher B

• V Alfven scales with B - radial group velocity should increase with B
so that wave

propagation into core (away from surface) is faster - surface fields
should decrease with B

> • Higher field may explain higher efficiency on DIII-D
>
> Results from this experiment are important for future applications of
> HHFW:
>
> • They will help in making projections to the higher field regime of
> the ST CTF
>
> • They will provide support for increasing the k~\|\|~ of the NSTX
> antenna for current drive phasing
>
> P~RF~ losses at the edge of the plasma have been detected earlier
> through modulation of the RF power to determine W and during the RF
> pulse(s), and from these the efficiency of core heating. It has been
> found that the efficiency is strongly dependent on the parallel wave
> number, k~\|\|~, launched with the antenna. For example, the
> efficiency has been observed to decrease from \~ 70% or greater at
> k~\|\|~ = 14m^-1^ to \~ 40% at k~\|\|~ = 7m^-1^ at B~T~ = 4.5 kG and
> I~P~ = 600 kA (series of shots around 112699) \[J. Hosea et al., 2005
> RF Conference\]. Thus the RF power loss is significantly greater for
> the lower k~\|\|~ case and it is important to understand the possible
> power loss channels as a function of k~\|\|~ and if the loss can be
> reduced to improve the performance of the HHFW heating and current
> drive on NSTX.
>
> One of the major loss channels on NSTX is from edge ion heating
> through the parametric decay instability. This decay of the fast wave
> into an ion Bernstein and ion cyclotron quasi-mode has been observed
> and correlated to very strong ion heating in the surface of the plasma
> \[J.R. Wilson et al., 2005 RF Conference\]. The ion heating and the
> percent of the applied RF power calculated to be needed to support it
> against the power lost by the edge ions through collisional coupling
> to
>
> ![](media/image1.jpeg){width="6.788888888888889in"
> height="2.811111111111111in"}
>
> the electrons is shown in Fig. 1 for the series of shots around
> 112699. Edge ion heating via parametric decay waves accounts for a
> substantial amount of RF power loss which increases somewhat with
> wavelength - 16%/23% loss for 14 m^-1^/-7 m^-1^. However, the very
> large reduction in RF heating efficiency observed at 7m^-1^ relative
> to that for 14m^-1^, as discussed earlier, requires large additional
> RF power loss of up to \~ 30% at the edge region of the plasma. This
> strong dependence of the RF power loss on parallel wave number and
> recalling that the loss was even more dramatic at k~\|\|~ = 3m^-1^
> suggests that this additional loss at lower k~\|\|~ may be due to the
> propagation properties of the launched fast waves themselves.
>
> The propagation characteristics of the fast wave can also affect power
> losses in the edge region of the plasma. The wave propagation onsets
> at lower density for lower k~\|\|~ since wave onset, kis proportional
> to B\*k~\|\|~^2^. Perpendicular wave number versus density curves with
> k~\|\|~ as a parameter are shown in Fig. 2 for B~T~ = 4.5 kG and f =
> 30 MHz. These curves are derived using the cold plasma dispersion
> relation for a two-component plasma in Eq. 1 and ignoring the pitch of
> the magnetic field:
>
> D = n)\*{nn~\|\|~^2^ (1+ KK~\|\|~) -- (K+ K~r~\*K~l~/K~\|\|~)\] +
> (-n~\|\|~^2^ + K~r~)\*(-n~\|\|~^2^ + K~l~)} = 0 (1)
>
> As indicated the onset density is \~ 2.6/0.6/0.1 in units of 10^12^
> cm^-3^ for k~\|\|~ = 14/7/3 m^-1^, respectively. Propagation is very
> close to the vessel wall at 7m^-1^ and on the wall at 3m^-1^. This
> should lead to higher power losses in the surface region of the plasma
> for lower k~\|\|~ .
>
> ![](media/image2.jpeg){width="3.540277777777778in"
> height="3.404166666666667in"}
>
> The group velocity of the launched fast waves is also important with
> regard to the speed with which the waves enter the plasma and leave
> the edge plasma region. The group velocity is given by (partial
> derivatives):
>
> v~g~ = *d*/*d***k** = - (*d*D/*d***k**)/(*d*D/*d*) (2)
>
> The v~g~and v~g\|\|~ values and their ratios for k~\|\|~ = 14 m^-1^
> and 7 m^-1^ for the conditions of Fig. 2 are given in Fig. 3. It is
> predicted that the perpendicular group velocity is lower in the mid
> 10^12^ cm^3^
>
> ![](media/image3.jpeg){width="6.377777777777778in" height="2.5in"}
>
> for the lower k~\|\|~ value. Furthermore, the perpendicular group
> velocity falls to a low value in the vicinity of the antenna for the
> lower k~\|\|~ value. Both of these effects will tend to produce higher
> RF fields in front of the antenna that in turn increase the PDI,
> sheath and collisional power losses. Also, the direction of the wave
> energy flow is only \~ 20^O^ from the field direction after the
> perpendicular group velocity increases away from propagation onset.
> Thus the waves tend to propagate in the surface of the plasma away
> from the antenna and the interaction with the antenna and wall
> structures is considerably greater at lower k~\|\|~ for which the wave
> propagation extends out to much lower density.
>
> ![](media/image4.jpeg){width="5.977777777777778in"
> height="2.388888888888889in"}
>
> magnetic field values. Propagation onset density decreases a factor of
> two at the lower field for both 7m^-1^ and 14m^-1^. Surface losses
> should increase substantially at the lower field - even at
>
> 14m^-1^. Perpendicular group velocity also decreases by a factor of \~
> 2 at 3 kG in the mid 10^12^ cm^-3^ density range so that wave fields
> should be enhanced even further at the lower field which should cause
> increased edge losses due to PDI, sheath and collisional effects.

# 3. Experimental run plan

A.  Setup stable shot at B = 4.5 kG, I~P~ = 600 kA similar to shot
    112699 (or good shot now after Li injection)

    -   Test point: Lower I~P~ somewhat if required to achieve
        acceptable stability

-   LSN, helium L-mode, gap 4-5 cm

-   Modulate P~RF~ as for shot 112699 with k~\|\|~ = 14 m^-1^

Bring P~RF~ up to \~ 2-3 MW (depending on conditions)

-   2 shots @ 14 m^-1^

-   1 shot ohmic

B.  Test low field scaling

-   Setup B = 3 kG, I~P~ = 400 kA discharge

```{=html}
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```
-   2shots @ 14 m^-1^

-   2 shots @ -7 m^-1^ (co CD)

-   2 shots @ 7 m^-1^ ( phasing)

-   1 shot ohmic

```{=html}
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```
-   Test point: Compare efficiency of 14 m^-1^ case to that for 4.5 kG

C.  Test high field scaling

-   Setup B = 5.5 kG, I~P~ = 730 kA discharge

```{=html}
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```
-   2 shots @ 14 m^-1^

-   2 shots @ -7 m^-1^ (co CD)

-   2 shots @ 7 m^-1^ (phasing)

-   1 shot ohmic

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

Stable or at least reproducible plasma conditions are required for the
quantitative comparisons of this XP. Critical diagnostics include:

-   Soft x-ray and Mirnov loops for stability

-   EFIT with high time resolution for W

-   Thomson scattering for electrons

-   Edge rotation diagnostic for edge heating

-   NPA for edge and core ion heating

-   Radiated power diagnostic

-   Reflectometry for edge density and PDI

-   Reflectometry for wave measurements for opposite side from antenna

-   Edge probe for PDI

-   Gap RF probes for leakage

-   RF probe(s) for edge RF field (highly desirable but not essential)

# 5. Expected results and planned analysis

**Expected results:**

-   Heating efficiencies vs B for 14 m^-1^, -7 m^-1^ (co CD) and 7 m^-1^
    ( phasing)

```{=html}
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```
-   Core heating from EFIT W

-   Core electron heating from Thomson scattering

```{=html}
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```
-   Edge heating/power loss

```{=html}
<!-- -->
```
-   Edge ion heating from edge rotation diagnostic

-   Edge electron heating from Thomson scattering

```{=html}
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```
-   Behavior of PDI characteristics and induced losses with field

-   Plasma profiles , core and edge, for permitting predictions of wave
    propagation and damping characteristics and of PDI produced losses

-   Relative surface wave amplitude for comparison to surface power loss
    for the explored conditions

-   Ceramic gap RF emission for the explored conditions

**Planned analysis:**

-   Calculation of and W for EFIT W to obtain percent P~RF~ deposited

-   Calculation of ~e~ and W~e~ for Thomson scattering W~e~ to obtain
    P~RF~ delivered to electrons

-   Compare efficiencies for the two field cases

-   Analysis of wave propagation and damping characteristics from onset
    density into the core of plasma - along field and perpendicular
    directions of the ray path, and including collisions - for
    predicting surface losses

-   Development of predictions for PDI losses

-   Projection of heating efficiency expected at 10 kG, with and without
    PDI present, to compare with DIII-D results and for higher field ST
    devices

# 6. Planned publication of results

The results will be submitted for publication in Physics of Plasmas by
the end of this year.

PHYSICS OPERATIONS REQUEST

Title: HHFW Power Balance vs B at Constant q Error: Reference source not
found

Machine conditions (specify ranges as appropriate)

> B~TF~ (kG): **3 - 5.5** Flattop start/stop (s): **0.0 / 0.6 or as
> normal**

I~P~ (MA): **0.4 -- 0.73** Flattop start/stop (s): **0.1 /0.6 or as for
112699**

Configuration: **Lower Single Null as for 112699 or as newly developed
this run**

> Outer gap (m): **4 -- 5 cm**, Inner gap (m): **\_\_\_\_\_**
>
> Elongation : **\_\_\_\_\_**, Triangularity : **\_\_\_\_\_**
>
> Z position (m): **0.00**
>
> Gas Species: **He**, Injector: **Inner Wall**
>
> ~~NBI~~ - Species: **D**, Sources: **A/B/C**, Voltage (kV):
> **\_\_\_\_\_**, Duration (s): **\_\_\_\_\_**

ICRF -- Power (MW): **up to 3 MW** Phasing: **-7/7()/14 m^-1^** Duration
(s): **0.3 sec**

**(modulated) as for 112699**

~~CHI~~: **On / Off**

*Either:* List previous shot numbers for setup: **112699**

*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: HHFW Power Balance vs B at Constant q Error: Reference source not
found

+-------------------------------+-----+----+--------------------------+
| #### Diagnostic               | ### | #  | #### Instructions        |
|                               | # N | ## |                          |
|                               | eed | #  |                          |
|                               |     | De |                          |
|                               |     | si |                          |
|                               |     | re |                          |
+-------------------------------+-----+----+--------------------------+
| > Bolometer - tangential      | > X |    | > Whatever is needed for |
| > array                       |     |    | > measuring Prad         |
+-------------------------------+-----+----+--------------------------+
| > Bolometer array - divertor  | > X |    |                          |
+-------------------------------+-----+----+--------------------------+
| > CHERS                       |     |    |                          |
+-------------------------------+-----+----+--------------------------+
| > Divertor fast camera        |     |    |                          |
+-------------------------------+-----+----+--------------------------+
| > Dust detector               |     |    |                          |
+-------------------------------+-----+----+--------------------------+
| > EBW radiometers             |     |    |                          |
+-------------------------------+-----+----+--------------------------+
| > Edge deposition monitor     |     |    |                          |
+-------------------------------+-----+----+--------------------------+
| > Edge pressure gauges        |     | >  |                          |
|                               |     |  X |                          |
+-------------------------------+-----+----+--------------------------+
| > Edge rotation spectroscopy  | > X |    | > Essential              |
+-------------------------------+-----+----+--------------------------+
| > Fast lost ion probes --     |     |    |                          |
| > IFLIP                       |     |    |                          |
+-------------------------------+-----+----+--------------------------+
| > Fast lost ion probes --     |     |    |                          |
| > SFLIP                       |     |    |                          |
+-------------------------------+-----+----+--------------------------+
| > Filtered 1D cameras         |     |    |                          |
+-------------------------------+-----+----+--------------------------+
| > Filterscopes                |     |    |                          |
+-------------------------------+-----+----+--------------------------+
| > FIReTIP                     |     |    |                          |
+-------------------------------+-----+----+--------------------------+
| > Gas puff imaging            |     |    |                          |
+-------------------------------+-----+----+--------------------------+
| > High-k scattering           |     |    |                          |
+-------------------------------+-----+----+--------------------------+
| > Infrared cameras            |     |    |                          |
+-------------------------------+-----+----+--------------------------+
| > Interferometer -- 1 mm      |     |    |                          |
+-------------------------------+-----+----+--------------------------+
| > Langmuir probes - PFC tiles |     | >  |                          |
|                               |     |  X |                          |
+-------------------------------+-----+----+--------------------------+
| > Langmuir probes - RF        | > X |    |                          |
| > antenna                     |     |    |                          |
+-------------------------------+-----+----+--------------------------+
| > Magnetics -- Diamagnetism   | > X |    |                          |
+-------------------------------+-----+----+--------------------------+
| > 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    | > X |    |                          |
| > array                       |     |    |                          |
+-------------------------------+-----+----+--------------------------+
| > MSE                         |     |    |                          |
+-------------------------------+-----+----+--------------------------+
| > Neutral particle analyzer   |     |    |                          |
+-------------------------------+-----+----+--------------------------+
| > Neutron Rate (2 fission, 4  |     |    |                          |
| > scint)                      |     |    |                          |
+-------------------------------+-----+----+--------------------------+
| > Neutron collimator          |     |    |                          |
+-------------------------------+-----+----+--------------------------+
| > Plasma TV                   | > X |    |                          |
+-------------------------------+-----+----+--------------------------+
| > Reciprocating probe         |     | >  |                          |
|                               |     |  X |                          |
+-------------------------------+-----+----+--------------------------+
| > Reflectometer - FM/CW       |     |    |                          |
+-------------------------------+-----+----+--------------------------+
| > Reflectometer - fixed       |     |    |                          |
| > frequency homodyne          |     |    |                          |
| > quadrature                  |     |    |                          |
+-------------------------------+-----+----+--------------------------+
| > Reflectometer - homodyne    |     | >  |                          |
| > correlation                 |     |  X |                          |
+-------------------------------+-----+----+--------------------------+
| > Reflectometer - HHFW/SOL    | > X |    |                          |
+-------------------------------+-----+----+--------------------------+
| > RF antenna camera           |     | >  |                          |
|                               |     |  X |                          |
+-------------------------------+-----+----+--------------------------+
| > RF antenna probe            | > X |    |                          |
+-------------------------------+-----+----+--------------------------+
| > Solid State NPA             |     |    |                          |
+-------------------------------+-----+----+--------------------------+
| > SPRED                       |     |    |                          |
+-------------------------------+-----+----+--------------------------+
| > Thomson scattering - 20     |     |    |                          |
| > channel                     |     |    |                          |
+-------------------------------+-----+----+--------------------------+
| > Thomson scattering - 30     | > X |    |                          |
| > channel                     |     |    |                          |
+-------------------------------+-----+----+--------------------------+
| > Ultrasoft X-ray arrays      | > X |    |                          |
+-------------------------------+-----+----+--------------------------+
| > Ultrasoft X-ray arrays - 2  |     |    |                          |
| > color                       |     |    |                          |
+-------------------------------+-----+----+--------------------------+
| > Visible bremsstrahlung det. |     |    |                          |
+-------------------------------+-----+----+--------------------------+
| > Visible spectrometers       |     |    |                          |
| > (VIPS)                      |     |    |                          |
+-------------------------------+-----+----+--------------------------+
| > X-ray crystal               |     |    |                          |
| > spectrometer - H            |     |    |                          |
+-------------------------------+-----+----+--------------------------+
| > X-ray crystal               |     |    |                          |
| > spectrometer - V            |     |    |                          |
+-------------------------------+-----+----+--------------------------+
| > X-ray pinhole camera        |     |    |                          |
+-------------------------------+-----+----+--------------------------+
| > High time resolution EFIT   | > X |    |                          |
+-------------------------------+-----+----+--------------------------+
| > Gap RF probes               | > X |    |                          |
+-------------------------------+-----+----+--------------------------+
| > RF probes for edge RF field |     | >  | > Highly desirable       |
|                               |     |  X |                          |
+-------------------------------+-----+----+--------------------------+
|                               |     |    |                          |
+-------------------------------+-----+----+--------------------------+