magnetically induced currents for selectively destroying pine beetles in situ (“sapzap”) 1....
TRANSCRIPT
MAGNETICALLY INDUCED CURRENTS FOR SELECTIVELY DESTROYING PINE
BEETLES IN SITU (“SAPZAP”)
1. Department of Electrical and Computer Engineering,
2. Neuroscience Program,
Howard Wachtel1,2 & Frank Barnes1
University of ColoradoBoulder CO 80309 USA
Outline of Talk
1. Introduction to Problem 2. Approach Using RF 3. Some Power Calculations
The Problem
Ravishing huge stands of lodgepole pine Colorado Rocky Mountains, west slope and elsewhere
Expected to cross the continental divideDestroy millions of trees along the Front Range
The Mountain Pine Beetle (MPB)"Dendroctonus Ponderosae“
Image from: www.global-greenhouse-warming.com
The Problem
Image: http://www.pherotech.com/page150.htm
Once a tree has been infiltrated by MPB
"conventional wisdom" holds that it
cannot be saved
So, often the first sign that beetles have
entered is also the "death knell" of the
tree.
The Solution
Image: http://www.pherotech.com/page150.htm
We believe that coniferous trees can be rescued if the MPB can be selectively destroyed within the tree
An approach to this may be to deploy highly selective hyperthermia.
Coniferous Tree (Pine, etc.) Characteristics -- Cross Section
The bark (outermost layer)
The next layer (xylem) The innermost layers
(growth rings or cortex)
The xylem layer."blood supply" of the tree. Interruption of sap
flow completely around the xylem circumference will inevitably lead to the death of the tree.
Usually quite dry and has a low electrical, as well as thermal, conductivity.
quite wet (sap laden) and high in electrolyte content so it is much more conductive.
relatively dry and low in conductance.
Coniferous Tree (Pine, etc.) Characteristics
Evidence, mainly from controlled forest fires ("burns") suggest that coniferous (pine, etc.) trees can survive fairly high temperature elevations as long as the xylem temperature does not exceed 60o C for an extended time period.
Mountain Pine Beetle (MPB) Characteristics
Adult MPBs – can bore through the bark of certain pine trees
(especially lodgepole) – settle in the xylem where they carve out "galleries” into
which the females lay eggs—and these hatch into larvae which remain in the cambium.
The MPB (and their larvae) – Produce a blue colored fungus, which spreads through
large portions of the xylem, – Fungus will block sap (nutrient) flow and this will kill the tree.
Mountain Pine Beetle (MPB) Characteristics
Logs cut from beetle infested trees have been "decontaminated" by thermal means including microwaving, solar heating, etc.
Temperatures in the range of 45 to 55oC have been reported to be effective in killing MPB and similar insects.
Similar temperatures might reasonably be expected to be lethal to MPB within living trees.
Energy Considerations for Hyperthermal Treatment of MPB Infested Trees
We hypothesize that an elevated cambial
temperature of about 55 degrees C, sustained for
several minutes to an hour or so, will selectively
destroy MPB and their larvae while doing only minor
damage to the tree.
Energy Considerations for Hyperthermal Treatment of MPB Infested Trees
A tree that has 1 meter length and 30 cm diameterThe sap layer has a circumference of about
one meter and a typical thickness of 0.5 cm
The sap volume (xylem) is about 5000cc. Energy required to raise its temperature from
say 25oC to 55oC would be 150,000 joules ( ~650,000 watt-seconds). Assuming no heat dissipation from that xylem layer
Energy Considerations for Hyperthermal Treatment of MPB Infested Trees
This could be achieved, for example, by inputting 6500 watts for 1000 seconds (17 minutes).
Taking into account thermal losses (cooling) to adjacent layers as well as source inefficiencies might reasonably double or triple this figure—but this still is within the realm of feasibility.
Pine Tree Forest
Possible Coil on Tree
~
Dielectric Constant as a Function of Depth into Tree [1]
Electric Field as a Function of Radius and Frequency
Calculations
NIdlH
cr
NIH
2
dSt
BdlE
S
tINfr
rfNI
r
rE
c
s
c
s cos102
27
2EP 1148.0 ms 1107.0 mc
N=10 I=10 f=1.35 107 Hz rc=5.5 cm
Conductivity as Function of Distance From the Surface.
r (mm)
0
0.1
0.2
0.3
0.4
0.5
0.61 4 7 10 13 16 19 22 25 28 31 34 37 40 43 46 49
E as Function of Distance From the Surface.
r (mm)
0.00
5.00
10.00
15.00
20.00
25.00
1 4 7 10 13 16 19 22 25 28 31 34 37 40 43 46 49
E
Power Density as Function of Distance From the Center
r (mm)
0.00
1.00
2.00
3.00
4.00
5.00
6.00
7.00
8.00
9.00
1 4 7 10 13 16 19 22 25 28 31 34 37 40 43 46 49
P
Work in Progress and To Be Done
1. An RF 1KW source at 13.5 MHz has been located and is being prepared for testing.
2. Short sections infected logs will be acquired from the Forest Service.
3. We will run tests on “zapping bugs” and measuring temperature profiles.
Acknowledgement to Seyitriza Tigrek for help in preparing the power points.