Wallace

Document Sample
Wallace Powered By Docstoc
					PARS Workshop November 2002




Short-pulse Heating: Theory, Experiments and Scaling



                               Tom Wallace
                           tom.wallace@apti.com




  ADVANCED POWER TECHNOLOGIES, INC.
Outline

Time domain measurements and impulse responses
   • Very simple way to predict results of “conventional” heating vs. f
   • Also shows how to optimize scanning
Impulse and frequency responses
   • Ionospheric heating
   • Earth-ionosphere waveguide
Implications for higher power facilities
   • What will the full HAARP facility produce?
   • Will the optimum heating frequency change?




   ADVANCED POWER TECHNOLOGIES, INC.
Time-Domain Measurements

When we measure an ionospheric signal in the time
  domain, we see the convolution of the response of
  the ionosphere to heating with the response of the
  Earth-ionosphere waveguide
With high time resolution measurements of short
  heating pulses, these two responses can be easily
  separated and examined
Recent time-domain measurements agree very well
  with theory and simulation


   ADVANCED POWER TECHNOLOGIES, INC.
Impulse Response of the Ionosphere

Short pulse heating allows us to measure the impulse
  response of the ionosphere directly:
   • Under the heated region, there are ~500 ms before the
     first echo arrives (~150 km round trip)
   • The impulse response typically lasts about 200 ms




   ADVANCED POWER TECHNOLOGIES, INC.
    Which Impulse Response to Look At?

           S(t) from a short heating pulse:                                                 B(t) from the same pulse:

)   0.12                                                                     )   2.5
s                                                                            s
t                                                                            t
i                                                                            i
n                                                                            n     2
u    0.1                                                                     u
y                                                                            y
r                                                                            r   1.5
a   0.08                                                                     a
r                                                                            r
t                                                                            t
i                                                                            i     1
b                                                                            b
r   0.06
                                                                             r
a                                                                            a   0.5
(                                                                            (
S   0.04                                                                     B
A
                                                                                   0


    0.02
                                                                                 -0.5


      0                                                                            -1
           0   0.2   0.4   0.6   0.8       1     1.2   1.4   1.6   1.8   2              0   0.1   0.2   0.3   0.4      0.5    0.6   0.7   0.8   0.9   1
                                       Time (ms)                                                                    Time (ms)




 In the past, we’ve looked at S(t) as a measure of performance in simulations.
Looking at B(t) is generally more useful, and it can be experimentally measured.



               ADVANCED POWER TECHNOLOGIES, INC.
  Why Does B(t) Look Like This?

                 m0 È                   ˆ
                                       r ∂                       ˆ
                                                                r˘
    B ( x, t ) =    Ú ÍJ[x, t ' ]ret ¥ r 2 + ∂t J[x, t ' ]ret ¥ cr ˙ dV
                 4p V Î                                            ˚
       If Ú J dV ª ÓEA, r ^ J and large compared to the size
                 of the source region, and E is constant,

                           AEm 0          È         r ∂       ˘
                B(x, t ) ª      2         Í Ó(t ) + c ∂t Ó(t )˙
                           4p r           Î                   ˚
So the magnetic field depends on both S(t) and its time derivative;
in fact, the derivative is usually more important even at close range


      ADVANCED POWER TECHNOLOGIES, INC.
What Determines S(t) and its Time Derivative?

Maximum value of S: electron density profile (ne vs. h), heated
 temperature profile (Te vs. h)
Heated temperature profile: electron density profile, nonlinearly
 on quiver energy (e.g. runaway)

Turn-on time constant: quiver energy and temperature profile
Turn-off time constant: temperature profile

Electron density profile is critical to determining heating
 altitude; all the following simulations use Barr & Stubbe’s
 profile 2 (normal nighttime polar ionosphere) and give good
 agreement with measurements.

   ADVANCED POWER TECHNOLOGIES, INC.
Impulse Response of 3.3 MHz Ionospheric Heating
                    Current HAARP FDP 960 kW X-mode
     )   2.5
     s
     t
     i
     n     2
     u

     y
     r   1.5
     a
     r
     t
     i     1
     b
     r
     a   0.5
     (

     B
           0


         -0.5


           -1
                0   0.1   0.2   0.3   0.4      0.5    0.6   0.7   0.8   0.9   1
                                            Time (ms)




  ADVANCED POWER TECHNOLOGIES, INC.
Frequency Response of 3.3 MHz Ionospheric Heating
             Current HAARP FDP 960 kW X-mode
       70


       60


       50
   e
   s
   n   40
   o
   p
   s
   e   30
   R

       20


       10


       0
         1               2                 3    4
       10              10                 10   10
                             Frequency (Hz)



  ADVANCED POWER TECHNOLOGIES, INC.
Impulse Response of the EIW at 0 km Range

  Observed values of the reflection coefficient R are 0.2-0.3
         1
                                   •
                         h(t ) = Â R nd (t - t r - (2n + 1) h / c )
        0.9

        0.8                       n =0

        0.7

        0.6

        0.5

        0.4

        0.3

        0.2

        0.1

         0
              0    0.5        1             1.5      2   2.5          3
                                         Time (ms)


  ADVANCED POWER TECHNOLOGIES, INC.
Frequency Response at 0 km Range

          1.5




      e    1
      s
      n
      o
      p
      s
      e
      R
          0.5




           0
             1               2                 3    4
           10              10                 10   10
                                 Frequency (Hz)




  ADVANCED POWER TECHNOLOGIES, INC.
Combined 3.3 MHz Response at 0 km

           90

           80

           70


       e   60
       s
       n
       o   50
       p
       s
       e   40
       R
           30

           20

           10

           0
             1               2                  3    4
           10              10                  10   10
                                  Frequency (Hz)




  ADVANCED POWER TECHNOLOGIES, INC.
Experimental 3.3 MHz Frequency Response at 12 km
        k
        H
        2
        z                     3.3 MHz Heating on 4 March 2001
        o 1.4
        t
        d
        e
        r
        a 1.2
        p
        m
        o
        C
            1
        l
        e
        v
        e
        L
          0.8
        d
        l
        e
        i
        F
          0.6
        e
        g
        a
        r
        e 0.4
        v
        A


          0.2




            0
                     2                            3                  4
                10                           10                 10
                                       Frequency (Hz)




  ADVANCED POWER TECHNOLOGIES, INC.
Impulse Response of the EIW at a Distance

                                                    Source



                                                             h



 Receiver                              d



            •
                                                          2
  h(t ) = Â R nd Ê t - t r - (2n + 1) h 2 + (d / (2n + 1)) / c ˆ
                 Á                                             ˜
          n =0   Ë                                             ¯



   ADVANCED POWER TECHNOLOGIES, INC.
Impulse Response of the EIW at 500 km Range

           1

         0.9

         0.8

         0.7

         0.6

         0.5

         0.4

         0.3

         0.2

         0.1

           0
               0    0.5       1          1.5      2   2.5   3
                                      Time (ms)




  ADVANCED POWER TECHNOLOGIES, INC.
Frequency Response of the EIW at 500 km

         1.5




     e    1
     s
     n
     o
     p
     s
     e
     R
         0.5




          0
            1               2                  3    4
          10              10                  10   10
                                 Frequency (Hz)




  ADVANCED POWER TECHNOLOGIES, INC.
Combined 3.3 MHz Response at 500 km

           70


           60


           50
       e
       s
       n   40
       o
       p
       s
       e   30
       R

           20


           10


           0
             1               2                  3    4
           10              10                  10   10
                                  Frequency (Hz)




  ADVANCED POWER TECHNOLOGIES, INC.
3.3 MHz Temperature Profile for Full HAARP Facility

                      Temperature after 500 ms heating
           90


           85


           80

         )
         m 75
         k
         (
         e 70
         d
         u
         t 65
         i
         t
         l
         A 60


           55


           50


           45


           40
                0   500     1000              1500            2000   2500   3000
                                   Electron Temperature (K)




  ADVANCED POWER TECHNOLOGIES, INC.
Full HAARP 3.3 MHz Impulse Response

       )   14
       s
       t
       i
       n   12
       u

       y   10
       r
       a
       r   8
       t
       i
       b   6
       r
       a
       (
           4
       B

           2


           0


           -2
                0   0.1   0.2   0.3   0.4      0.5    0.6   0.7   0.8   0.9   1
                                            Time (ms)




  ADVANCED POWER TECHNOLOGIES, INC.
Full HAARP 3.3 MHz Frequency Spectrum
                   Full HAARP 3.6 MW X-mode
          350


          300


          250
      e
      s
      n   200
      o
      p
      s
      e   150
      R

          100


          50


           0
             1               2                 3    4
           10              10                 10   10
                                 Frequency (Hz)




  ADVANCED POWER TECHNOLOGIES, INC.
Ratio of Full HAARP to Current FDP Field

          10

          9

          8

          7

      o
      i   6
      t
      a
      R   5

          4

          3

          2

          1
            1                2                 3    4
          10               10                 10   10
                                 Frequency (Hz)




  ADVANCED POWER TECHNOLOGIES, INC.
Full HAARP 3.3 MHz Heating at 0 km Range
          Predicted Response for “Conventional” Heating
        500

        450

        400

        350
    e
    s   300
    n
    o
    p   250
    s
    e
    R   200

        150

        100

        50

         0
           1               2                  3      4
         10              10                  10    10
                                Frequency (Hz)



  ADVANCED POWER TECHNOLOGIES, INC.
Full HAARP 3.3 MHz Heating at 500 km Range
               Predicted Response for “Conventional” Heating
         400


         350


         300

     e
     s   250
     n
     o
     p   200
     s
     e
     R   150


         100


         50


          0
            1               2                  3        4
          10               10                 10       10
                                 Frequency (Hz)




  ADVANCED POWER TECHNOLOGIES, INC.
Summary

“Conventional” heating is predicted to produce
  higher fields than the ~3.75x increase expected
  from a simple power scaling (result of faster
  heating and runaway)
Not yet clear what to expect at higher frequencies
  with full HAARP
   • Higher frequencies mean higher heating altitudes; this
     produces higher S(t), but slower changes
This result will suggest optimum scanning strategy
  for the full HAARP

   ADVANCED POWER TECHNOLOGIES, INC.

				
DOCUMENT INFO
Shared By:
Categories:
Tags:
Stats:
views:2
posted:10/20/2011
language:English
pages:24