Beam-Target Interactions - Revision history

Lwcamp: /* Melting */

2026-04-18T15:19:58Z

Melting

← Older revision		Revision as of 08:19, 18 April 2026
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	==Melting==		==Melting==

	This is one of the big ones. If you bring a material up to its melting temperature, it will – no surprise – start to melt. The act of melting absorbs heat. The amount of heat it takes to melt a given mass (a kg, say) of a material is its <i>specific heat of fusion</i> (which, confusingly, has nothing to do with nuclear fusion). If your beam's heat has time to diffuse through the body, then once melting starts the temperature will never get any higher than the melting temperature until the entire target is melted. In practice, though, you are adding heat much faster than this. So you have a hot surface with a temperature higher than the melting temperature that conducts heat to the melt-solid interface, At this interface, heat is used to turn the material from solid to liquid rather than increasing the temperature. And then beyond that, you have heat being conducted from the interface into the rest of the material.		This is one of the big ones. If you bring a material up to its melting temperature, it will – no surprise – start to melt. The act of melting absorbs heat. The amount of heat it takes to melt a given mass (a kg, say) of a material is its <i>specific heat of fusion</i> (which, confusingly, has nothing to do with nuclear fusion). If your beam's heat has time to diffuse through the body, then once melting starts the temperature will never get any higher than the melting temperature until the entire target is melted. In practice, though, you are adding heat much faster than this. So you have a hot molten surface with a temperature higher than the melting temperature that conducts heat to the melt-solid interface, At this interface, heat is used to turn the material from solid to liquid rather than increasing the temperature. And then beyond that, you have heat being conducted from the interface into the rest of the material.

	==Vaporization==		==Vaporization==

Lwcamp: /* Cooking */

2026-04-18T15:18:31Z

Cooking

← Older revision		Revision as of 08:18, 18 April 2026
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	Incapacitation will be rapid and shock can be expected within minutes. The percentage of skin burned can be estimated with the rule of nines, which assigns 9% of an adult's skin surface area to the head, 9% to each arm, 9% to each upper and lower leg (so 18% for each entire leg), 36% (four 9% sections) to the torso, and the remaining 1% to the genitalia. Because only one side of a person will be facing the beam, the available area to be burned will be halved.		Incapacitation will be rapid and shock can be expected within minutes. The percentage of skin burned can be estimated with the rule of nines, which assigns 9% of an adult's skin surface area to the head, 9% to each arm, 9% to each upper and lower leg (so 18% for each entire leg), 36% (four 9% sections) to the torso, and the remaining 1% to the genitalia. Because only one side of a person will be facing the beam, the available area to be burned will be halved.

	The combination of effects of burning and combustion is that if you are looking for a heat ray that can act like a long-range flame thrower, try to deliver around 120 J/cm² in under a second over as large of an area as possible. You'll ignite anything flammable, like clothes or hair, and cause fourth burns to exposed skin and second or worse degree burns to skin under clothes. And those flaming clothes will further burn the skin that they originally protected from your beam.		The combination of effects of burning and combustion is that if you are looking for a heat ray that can act like a long-range flame thrower, try to deliver around 120 J/cm² in under a second over as large of an area as possible. You'll ignite anything flammable, like clothes or hair, and cause fourth degree burns to exposed skin and second or worse degree burns to skin under clothes. And those flaming clothes will further burn the skin that they originally protected from your beam.

	==Melting==		==Melting==

Lwcamp at 18:58, 7 March 2026

2026-03-07T18:58:46Z

← Older revision		Revision as of 11:58, 7 March 2026
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	==References==		==References==

	[[Category:Lasers]][[Category:Beams]][[Category:Physics & Engineering]]		[[Category:Lasers]][[Category:Beams]][[Category:Physics & Engineering]][[Category:Physics & Math & Engineering]]

Lwcamp: /* Vapor explosion */

2026-02-19T06:10:43Z

Vapor explosion

← Older revision		Revision as of 23:10, 18 February 2026
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	<table style="margin-top:0.5em; margin-bottom:0.5em; text-align: center;" align="center" cellpadding="0" cellspacing="0" >		<table style="margin-top:0.5em; margin-bottom:0.5em; text-align: center;" align="center" cellpadding="0" cellspacing="0" >
	<tr>		<tr>
	<td rowspan="2" nowrap="nowrap" align="right"> <i>r</i> = <span style="font-size: 250%;">(</span>		<td rowspan="2" nowrap="nowrap" align="right"> <i>r</i> =
			<td rowspan="2" nowrap="nowrap" align="right"> <span style="font-size: 250%;">(</span>
	<td nowrap="nowrap">   3 <i>V</i>		<td nowrap="nowrap">   3 <i>V</i>
	<td rowspan="2" nowrap="nowrap" align="right"> <span style="font-size: 250%;">)</span>		<td rowspan="2" nowrap="nowrap" align="right"> <span style="font-size: 250%;">)</span>

Lwcamp: /* Vapor explosion */

2026-02-19T06:10:17Z

Vapor explosion

← Older revision		Revision as of 23:10, 18 February 2026
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	<table style="margin-top:0.5em; margin-bottom:0.5em; text-align: center;" align="center" cellpadding="0" cellspacing="0" >		<table style="margin-top:0.5em; margin-bottom:0.5em; text-align: center;" align="center" cellpadding="0" cellspacing="0" >
	<tr>		<tr>
	<td rowspan="2" nowrap="nowrap" align="right"> <i>v</i> = <span style="font-size: ~~150~~%;">√</span>		<td rowspan="2" nowrap="nowrap" align="right"> <i>v</i> =
			<td rowspan="2" nowrap="nowrap" align="right"> <span style="font-size: 250%;">√</span>
	<td style="border-top:solid 1px black;" nowrap="nowrap">   2 <i>p</i><sub>vapor</sub>		<td style="border-top:solid 1px black;" nowrap="nowrap">   2 <i>p</i><sub>vapor</sub>
	<tr>		<tr>
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	<table style="margin-top:0.5em; margin-bottom:0.5em; text-align: center;" align="center" cellpadding="0" cellspacing="0" >		<table style="margin-top:0.5em; margin-bottom:0.5em; text-align: center;" align="center" cellpadding="0" cellspacing="0" >
	<tr>		<tr>
	<td rowspan="2" nowrap="nowrap" align="right"> <i>v</i> = <span style="font-size: ~~150~~%;">√</span>		<td rowspan="2" nowrap="nowrap" align="right"> <i>v</i> =
			<td rowspan="2" nowrap="nowrap" align="right"> <span style="font-size: 250%;">√</span>
	<td style="border-top:solid 1px black;" nowrap="nowrap">   2 (<i>p</i><sub>vapor</sub> - <i>K<sub>h</sub></i>)		<td style="border-top:solid 1px black;" nowrap="nowrap">   2 (<i>p</i><sub>vapor</sub> - <i>K<sub>h</sub></i>)
	<tr>		<tr>

Lwcamp: /* Radiation */

2026-02-19T06:07:05Z

Radiation

← Older revision		Revision as of 23:07, 18 February 2026
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	<table style="margin-top:0.5em; margin-bottom:0.5em; text-align: center;" align="center" cellpadding="0" cellspacing="0" >		<table style="margin-top:0.5em; margin-bottom:0.5em; text-align: center;" align="center" cellpadding="0" cellspacing="0" >
	<tr>		<tr>
	<td rowspan="2" nowrap="nowrap" align="right"> <i>T<sub>rs</sub></i> = <span style="font-size: 250%;">(</span>		<td rowspan="2" nowrap="nowrap" align="right"> <i>T<sub>rs</sub></i> =
			<td rowspan="2" nowrap="nowrap" align="right"> <span style="font-size: 250%;">(</span>
	<td nowrap="nowrap">   <i>P</i>		<td nowrap="nowrap">   <i>P</i>
	<td rowspan="2" nowrap="nowrap" align="right"> <span style="font-size: 250%;">)</span>		<td rowspan="2" nowrap="nowrap" align="right"> <span style="font-size: 250%;">)</span>
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	<table style="margin-top:0.5em; margin-bottom:0.5em; text-align: center;" align="center" cellpadding="0" cellspacing="0" >		<table style="margin-top:0.5em; margin-bottom:0.5em; text-align: center;" align="center" cellpadding="0" cellspacing="0" >
	<tr>		<tr>
	<td rowspan="2" nowrap="nowrap" align="right"> <i>T<sub>ra</sub></i> = <span style="font-size: 250%;">(</span>		<td rowspan="2" nowrap="nowrap" align="right"> <i>T<sub>ra</sub></i> =
			<td rowspan="2" nowrap="nowrap" align="right"> <span style="font-size: 250%;">(</span>
	<td nowrap="nowrap">   <i>P</i>		<td nowrap="nowrap">   <i>P</i>
	<td rowspan="2" nowrap="nowrap" align="right"> <span style="font-size: 250%;">)</span>		<td rowspan="2" nowrap="nowrap" align="right"> <span style="font-size: 250%;">)</span>

Lwcamp: /* Radiation */

2026-02-18T00:36:10Z

Radiation

← Older revision		Revision as of 17:36, 17 February 2026
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	where σ<sub><i>SB</i></sub> = 5.67 × 10<sup>-8</sup> W/m<sup>2</sup>/K<sup>4</sup> is the <i>Stephan-Boltzmann constant</i>.		where σ<sub><i>SB</i></sub> = 5.67 × 10<sup>-8</sup> W/m<sup>2</sup>/K<sup>4</sup> is the <i>Stephan-Boltzmann constant</i>.
	The maximum temperature the body as a whole will reach (which will limit the temperature you can reach for the zero-dimensional heat conduction case) is		The maximum temperature the body as a whole will reach (which will limit the temperature you can reach for the zero-dimensional heat conduction case) is
	<div class="center" style="width: auto; margin-left: auto; margin-right: auto;"><~~math~~>		<div class="center" style="width: auto; margin-left: auto; margin-right: auto;">
	~~T_{~~ra} = ~~\left~~( ~~\frac{~~P~~}{A \, \sigma_{SB}} \~~right)^{1/4}		<table style="margin-top:0.5em; margin-bottom:0.5em; text-align: center;" align="center" cellpadding="0" cellspacing="0" >
	</~~math~~></div>		<tr>
	where <~~math~~>A</~~math~~> is the surface area of the object being heated.		<td rowspan="2" nowrap="nowrap" align="right"> <i>T<sub>ra</sub></i> = <span style="font-size: 250%;">(</span>
			<td nowrap="nowrap">   <i>P</i>
			<td rowspan="2" nowrap="nowrap" align="right"> <span style="font-size: 250%;">)</span>
			<td nowrap="nowrap"> <sup>1/4</sup>
			<tr>
			<td style="border-top:solid 1px black;"> <i>A</i> σ<sub><i>SB</i></sub>
			<td>
			</table>
			</div>
			where <i>A</i> is the surface area of the object being heated.

	===Temperature thresholds===		===Temperature thresholds===

Lwcamp: /* Radiation */

2026-02-18T00:34:20Z

Radiation

← Older revision		Revision as of 17:34, 17 February 2026
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	</table>		</table>
	</div>		</div>
	where <~~math~~>~~\sigma_{~~SB} = 5.67 \times 10^{-8~~} \mbox{~~W}/~~\mbox{~~m}^2/~~\mbox{~~K}^4</~~math~~> is the <i>Stephan-Boltzmann constant</i>.		where σ<sub><i>SB</i></sub> = 5.67 × 10<sup>-8</sup> W/m<sup>2</sup>/K<sup>4</sup> is the <i>Stephan-Boltzmann constant</i>.
	The maximum temperature the body as a whole will reach (which will limit the temperature you can reach for the zero-dimensional heat conduction case) is		The maximum temperature the body as a whole will reach (which will limit the temperature you can reach for the zero-dimensional heat conduction case) is
	<div class="center" style="width: auto; margin-left: auto; margin-right: auto;"><math>		<div class="center" style="width: auto; margin-left: auto; margin-right: auto;"><math>

Lwcamp: /* Radiation */

2026-02-18T00:32:40Z

Radiation

← Older revision		Revision as of 17:32, 17 February 2026
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	All the discussion of heat conduction was assuming that conduction was the only way to get rid of heat. It's not. Hot objects can also radiate heat away. A proper analysis would take into account the radiation as well as the actual geometry of heat conduction. If you need to get this much detail, become an engineer and find an employer who will let you use their FEM software. But for the purpose of understanding how beam weapons heating an object will work, it is easiest to just mention that radiation will put an upper limit on the temperature the target can reach, when the amount of heat being radiated off into the environment is equal to the amount of heat being absorbed by the beam. Emissivity affects radiation away from the target in the same way as absorption of beam energy into the target, so if the beam has the same kind of radiation as is being radiated away, the emissivity will make no difference. Emissivity only comes into play if the beam radiation is significantly different than the heat radiation being shed from the target. Ignoring these differences in emissivity, the maximum temperature the beam-illuminated spot can reach is		All the discussion of heat conduction was assuming that conduction was the only way to get rid of heat. It's not. Hot objects can also radiate heat away. A proper analysis would take into account the radiation as well as the actual geometry of heat conduction. If you need to get this much detail, become an engineer and find an employer who will let you use their FEM software. But for the purpose of understanding how beam weapons heating an object will work, it is easiest to just mention that radiation will put an upper limit on the temperature the target can reach, when the amount of heat being radiated off into the environment is equal to the amount of heat being absorbed by the beam. Emissivity affects radiation away from the target in the same way as absorption of beam energy into the target, so if the beam has the same kind of radiation as is being radiated away, the emissivity will make no difference. Emissivity only comes into play if the beam radiation is significantly different than the heat radiation being shed from the target. Ignoring these differences in emissivity, the maximum temperature the beam-illuminated spot can reach is
	<div class="center" style="width: auto; margin-left: auto; margin-right: auto;"><~~math~~>		<div class="center" style="width: auto; margin-left: auto; margin-right: auto;">
	~~T_{~~rs} = ~~\left~~( ~~\frac{~~P}{(\pi/4) \, S^2 ~~\, \sigma_{~~SB~~}} \right)^{1~~/4}		<table style="margin-top:0.5em; margin-bottom:0.5em; text-align: center;" align="center" cellpadding="0" cellspacing="0" >
	</~~math~~></div>		<tr>
			<td rowspan="2" nowrap="nowrap" align="right"> <i>T<sub>rs</sub></i> = <span style="font-size: 250%;">(</span>
			<td nowrap="nowrap">   <i>P</i>
			<td rowspan="2" nowrap="nowrap" align="right"> <span style="font-size: 250%;">)</span>
			<td nowrap="nowrap"> <sup>1/4</sup>
			<tr>
			<td style="border-top:solid 1px black;"> (π/4) <i>S</i><sup>2</sup> σ<sub><i>SB</i></sub>
			<td>
			</table>
			</div>
	where <math>\sigma_{SB} = 5.67 \times 10^{-8} \mbox{W}/\mbox{m}^2/\mbox{K}^4</math> is the <i>Stephan-Boltzmann constant</i>.		where <math>\sigma_{SB} = 5.67 \times 10^{-8} \mbox{W}/\mbox{m}^2/\mbox{K}^4</math> is the <i>Stephan-Boltzmann constant</i>.
	The maximum temperature the body as a whole will reach (which will limit the temperature you can reach for the zero-dimensional heat conduction case) is		The maximum temperature the body as a whole will reach (which will limit the temperature you can reach for the zero-dimensional heat conduction case) is

Lwcamp: /* Heat conduction */

2026-02-18T00:24:26Z

Heat conduction

← Older revision		Revision as of 17:24, 17 February 2026
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	<table border=1>		<table border=1>
	<tr><td>		<tr><td>
			<b>Doin' Da Math</b>

	To describe the diffusion of heat we will want a few characteristics of the material		To describe the diffusion of heat we will want a few characteristics of the material
	<ul>		<ul>