Internal Transport Barrier - Revision history

Admin: Updated links

2016-10-17T10:04:19Z

Updated links

Admin: /* Physical mechanism */

2010-07-30T14:28:46Z

Physical mechanism

← Older revision		Revision as of 16:28, 30 July 2010
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	<ref>[http://dx.doi.org/10.1088/0029-5515/44/4/R01 J.W. Connor et al, ''A review of internal transport barrier physics for steady-state operation of tokamaks'', Nucl. Fusion '''44''' (2004) R1-R49]</ref>		<ref>[http://dx.doi.org/10.1088/0029-5515/44/4/R01 J.W. Connor et al, ''A review of internal transport barrier physics for steady-state operation of tokamaks'', Nucl. Fusion '''44''' (2004) R1-R49]</ref>
	* The power deposited inside the [[Flux surface\|magnetic surface]], and/or local pressure gradients		* The power deposited inside the [[Flux surface\|magnetic surface]], and/or local pressure gradients
	* [[Magnetic shear]] and the shape of the rotational transform profile (e.g., reversed shear)		* [[Magnetic shear]] and the shape of the [[Rotational transform\|rotational transform]] profile (e.g., reversed shear)
	* MHD activity		* MHD activity
	* Momentum torques (poloidal or toroidal)		* Momentum torques (poloidal or toroidal)

Admin: /* Physical mechanism */

2009-08-30T07:59:16Z

Physical mechanism

← Older revision		Revision as of 09:59, 30 August 2009
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	The general consensus is that ITBs are the consequence of turbulence suppression due to sheared (''E'' × ''B'') flows.		The general consensus is that ITBs are the consequence of turbulence suppression due to sheared (''E'' × ''B'') flows.
	<ref>[http://link.aip.org/link/?PHPAEN/4/1499/1 K.H. Burrell, ''Effects of E × B velocity shear and magnetic shear on turbulence and transport in magnetic confinement devices'', Phys. Plasmas '''4''' (1997) 1499]</ref>		<ref>[http://link.aip.org/link/?PHPAEN/4/1499/1 K.H. Burrell, ''Effects of E × B velocity shear and magnetic shear on turbulence and transport in magnetic confinement devices'', Phys. Plasmas '''4''' (1997) 1499]</ref>
	This ~~mechanism~~ is ~~evidently~~ related to ~~the mechanism for~~ the formation of the [[H-mode]] barrier.		Such sheared flows can be generated by the turbulence itself via the [[Reynolds stress]] mechanism.
			This process is related to the formation of the [[H-mode]] barrier.

	ITBs are often found to be associated with rational magnetic surfaces.		ITBs are often found to be associated with rational magnetic surfaces.

Admin: /* Physical mechanism */

2009-08-29T14:07:56Z

Physical mechanism

← Older revision		Revision as of 16:07, 29 August 2009
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	* Enhanced collisionless losses of trapped particles, generating a radial electric field <ref>[http://link.aps.org/doi/10.1103/PhysRevLett.86.5910 U. Stroth et al, ''Internal Transport Barrier Triggered by Neoclassical Transport in W7-AS'', Phys. Rev. Lett. '''86''' (2001) 5910 - 5913]</ref>		* Enhanced collisionless losses of trapped particles, generating a radial electric field <ref>[http://link.aps.org/doi/10.1103/PhysRevLett.86.5910 U. Stroth et al, ''Internal Transport Barrier Triggered by Neoclassical Transport in W7-AS'', Phys. Rev. Lett. '''86''' (2001) 5910 - 5913]</ref>
	* Reduced collisional damping, allowing the growth of zonal flows <ref>[http://link.aip.org/link/?PHPAEN/14/020702/1 K. Itoh et al, ''Physics of internal transport barrier of toroidal helical plasmas'', Phys. Plasmas '''14''' (2007) 020702]</ref>		* Reduced collisional damping, allowing the growth of zonal flows <ref>[http://link.aip.org/link/?PHPAEN/14/020702/1 K. Itoh et al, ''Physics of internal transport barrier of toroidal helical plasmas'', Phys. Plasmas '''14''' (2007) 020702]</ref>

			The relation between some of these factors can be understood from the steady state ion force balance for the radial electric field:

			:<math>E_r = \frac{1}{Zen_e}\nabla p_i -v_\theta B_\phi + v_\phi B_\theta</math>

			Thus, gradients in any of the quantities appearing in this equation may lead to sheared ''E'' × ''B'' flows.

	== References ==		== References ==
	<references />		<references />

Admin: /* Physical mechanism */

2009-08-28T15:01:48Z

Physical mechanism

← Older revision		Revision as of 17:01, 28 August 2009
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	== Physical mechanism ==		== Physical mechanism ==

	The mechanism for the formation of Internal Transport Barriers in magnetically confined plasmas is complex and not fully understood. ~~Probably, it~~ is ~~related to the mechanism for~~ the ~~formation~~ of ~~the [[H-mode]] barrier, involving~~ turbulence suppression by sheared (''E'' × ''B'') flows.		The mechanism for the formation of Internal Transport Barriers in magnetically confined plasmas is complex and not fully understood.
			The general consensus is that ITBs are the consequence of turbulence suppression due to sheared (''E'' × ''B'') flows.
	<ref>[http://link.aip.org/link/?PHPAEN/4/1499/1 K.H. Burrell, ''Effects of E × B velocity shear and magnetic shear on turbulence and transport in magnetic confinement devices'', Phys. Plasmas '''4''' (1997) 1499]</ref>		<ref>[http://link.aip.org/link/?PHPAEN/4/1499/1 K.H. Burrell, ''Effects of E × B velocity shear and magnetic shear on turbulence and transport in magnetic confinement devices'', Phys. Plasmas '''4''' (1997) 1499]</ref>
			This mechanism is evidently related to the mechanism for the formation of the [[H-mode]] barrier.

	ITBs are often found to be associated with rational magnetic surfaces.		ITBs are often found to be associated with rational magnetic surfaces.

	Factors contributing to the formation of ITBs include:		Factors contributing to the formation of ITBs include:
	<ref>[http://dx.doi.org/10.1088/0029-5515/44/4/R01 J.W. Connor et al, ''A review of internal transport barrier physics for steady-state operation of tokamaks'', Nucl. Fusion '''44''' (2004) R1-R49]</ref>		<ref>[http://dx.doi.org/10.1088/0029-5515/44/4/R01 J.W. Connor et al, ''A review of internal transport barrier physics for steady-state operation of tokamaks'', Nucl. Fusion '''44''' (2004) R1-R49]</ref>
	* ~~Power~~ deposited inside the [[Flux surface\|magnetic surface]], and/or pressure gradients		* The power deposited inside the [[Flux surface\|magnetic surface]], and/or local pressure gradients
	* [[Magnetic shear]] and the shape of the rotational transform profile		* [[Magnetic shear]] and the shape of the rotational transform profile (e.g., reversed shear)
	* MHD activity		* MHD activity
	* Momentum torques (poloidal or toroidal)		* Momentum torques (poloidal or toroidal)

Admin: /* Physical mechanism */

2009-08-28T12:39:52Z

Physical mechanism

← Older revision		Revision as of 14:39, 28 August 2009
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	The mechanism for the formation of Internal Transport Barriers in magnetically confined plasmas is complex and not fully understood. Probably, it is related to the mechanism for the formation of the [[H-mode]] barrier, involving turbulence suppression by sheared (''E'' × ''B'') flows.		The mechanism for the formation of Internal Transport Barriers in magnetically confined plasmas is complex and not fully understood. Probably, it is related to the mechanism for the formation of the [[H-mode]] barrier, involving turbulence suppression by sheared (''E'' × ''B'') flows.
			<ref>[http://link.aip.org/link/?PHPAEN/4/1499/1 K.H. Burrell, ''Effects of E × B velocity shear and magnetic shear on turbulence and transport in magnetic confinement devices'', Phys. Plasmas '''4''' (1997) 1499]</ref>
	ITBs are often found to be associated with rational magnetic surfaces.		ITBs are often found to be associated with rational magnetic surfaces.

Admin: /* Physical mechanism */

2009-08-28T12:29:48Z

Physical mechanism

← Older revision		Revision as of 14:29, 28 August 2009
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	== Physical mechanism ==		== Physical mechanism ==

	The mechanism for the formation of Internal Transport Barriers in magnetically confined plasmas is complex and not fully understood. Probably, it is related to the mechanism for the formation of the [[H-mode]] barrier, involving turbulence suppression by sheared flows~~, and possibly~~ associated with rational magnetic surfaces.		The mechanism for the formation of Internal Transport Barriers in magnetically confined plasmas is complex and not fully understood. Probably, it is related to the mechanism for the formation of the [[H-mode]] barrier, involving turbulence suppression by sheared (''E'' × ''B'') flows.
			ITBs are often found to be associated with rational magnetic surfaces.

	Factors contributing to the formation of ITBs include:		Factors contributing to the formation of ITBs include:
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	* MHD activity		* MHD activity
	* Momentum torques (poloidal or toroidal)		* Momentum torques (poloidal or toroidal)
	* Reduced collisional damping <ref>[http://link.aip.org/link/?PHPAEN/14/020702/1 K. Itoh et al, ''Physics of internal transport barrier of toroidal helical plasmas'', Phys. Plasmas '''14''' (2007) 020702]</ref>		* Enhanced collisionless losses of trapped particles, generating a radial electric field <ref>[http://link.aps.org/doi/10.1103/PhysRevLett.86.5910 U. Stroth et al, ''Internal Transport Barrier Triggered by Neoclassical Transport in W7-AS'', Phys. Rev. Lett. '''86''' (2001) 5910 - 5913]</ref>
			* Reduced collisional damping, allowing the growth of zonal flows <ref>[http://link.aip.org/link/?PHPAEN/14/020702/1 K. Itoh et al, ''Physics of internal transport barrier of toroidal helical plasmas'', Phys. Plasmas '''14''' (2007) 020702]</ref>

	== References ==		== References ==
	<references />		<references />

Admin: /* Physical mechanism */

2009-08-28T12:21:48Z

Physical mechanism

← Older revision		Revision as of 14:21, 28 August 2009
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	* MHD activity		* MHD activity
	* Momentum torques (poloidal or toroidal)		* Momentum torques (poloidal or toroidal)
	* ~~Collisional~~ damping <ref>[http://link.aip.org/link/?PHPAEN/14/020702/1 K. Itoh et al, ''Physics of internal transport barrier of toroidal helical plasmas'', Phys. Plasmas '''14''' (2007) 020702]</ref>		* Reduced collisional damping <ref>[http://link.aip.org/link/?PHPAEN/14/020702/1 K. Itoh et al, ''Physics of internal transport barrier of toroidal helical plasmas'', Phys. Plasmas '''14''' (2007) 020702]</ref>

	== References ==		== References ==
	<references />		<references />

Admin: /* Physical mechanism */

2009-08-28T12:16:40Z

Physical mechanism

← Older revision		Revision as of 14:16, 28 August 2009
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	* MHD activity		* MHD activity
	* Momentum torques (poloidal or toroidal)		* Momentum torques (poloidal or toroidal)
			* Collisional damping <ref>[http://link.aip.org/link/?PHPAEN/14/020702/1 K. Itoh et al, ''Physics of internal transport barrier of toroidal helical plasmas'', Phys. Plasmas '''14''' (2007) 020702]</ref>

	== References ==		== References ==
	<references />		<references />

Admin at 16:51, 27 August 2009

2009-08-27T16:51:26Z

← Older revision		Revision as of 18:51, 27 August 2009
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	ITBs can be actively produced by modifying the current profile using external means.		ITBs can be actively produced by modifying the current profile using external means.
	<ref>[http://dx.doi.org/10.1088/0741-3335/45/1/201 R.C. Wolf, ''Internal transport barriers in tokamak plasmas'', Plasma Phys. Control. Fusion '''45''' (2003) R1-R91]</ref>		<ref>[http://dx.doi.org/10.1088/0741-3335/45/1/201 R.C. Wolf, ''Internal transport barriers in tokamak plasmas'', Plasma Phys. Control. Fusion '''45''' (2003) R1-R91]</ref>
	They are used to improve plasma confinement and stability properties, and to drive additional bootstrap current. Therefore, they are included in some alternative operational scenarios for [[ITER]].		They are used to improve plasma confinement and stability properties, and to drive additional [[Bootstrap current\|bootstrap current]]. Therefore, they are included in some alternative operational scenarios for [[ITER]].

	== Physical mechanism ==		== Physical mechanism ==

← Older revision		Revision as of 12:04, 17 October 2016
Line 2:		Line 2:

	ITBs can be actively produced by modifying the current profile using external means.		ITBs can be actively produced by modifying the current profile using external means.
	<ref>~~[http://dx.doi.org/10.1088/0741-3335/45/1/201~~ R.C. Wolf, ''Internal transport barriers in tokamak plasmas'', Plasma Phys. Control. Fusion '''45''' (2003) R1-R91]</ref>		<ref>R.C. Wolf, ''Internal transport barriers in tokamak plasmas'', [[doi:10.1088/0741-3335/45/1/201\|Plasma Phys. Control. Fusion '''45''' (2003) R1-R91]]</ref>
	They are used to improve plasma confinement and stability properties, and to drive additional [[Bootstrap current\|bootstrap current]]. Therefore, they are included in some alternative operational scenarios for [[ITER]].		They are used to improve plasma confinement and stability properties, and to drive additional [[Bootstrap current\|bootstrap current]]. Therefore, they are included in some alternative operational scenarios for [[ITER]].

Line 9:		Line 9:
	The mechanism for the formation of Internal Transport Barriers in magnetically confined plasmas is complex and not fully understood.		The mechanism for the formation of Internal Transport Barriers in magnetically confined plasmas is complex and not fully understood.
	The general consensus is that ITBs are the consequence of turbulence suppression due to sheared (''E'' × ''B'') flows.		The general consensus is that ITBs are the consequence of turbulence suppression due to sheared (''E'' × ''B'') flows.
	<ref>~~[http://link.aip.org/link/?PHPAEN/4/1499/1~~ K.H. Burrell, ''Effects of E × B velocity shear and magnetic shear on turbulence and transport in magnetic confinement devices'', Phys. Plasmas '''4''' (1997) 1499]</ref>		<ref>K.H. Burrell, ''Effects of E × B velocity shear and magnetic shear on turbulence and transport in magnetic confinement devices'', [[doi:10.1063/1.872367\|Phys. Plasmas '''4''' (1997) 1499]]</ref>
	Such sheared flows can be generated by the turbulence itself via the [[Reynolds stress]] mechanism.		Such sheared flows can be generated by the turbulence itself via the [[Reynolds stress]] mechanism.
	This process is related to the formation of the [[H-mode]] barrier.		This process is related to the formation of the [[H-mode]] barrier.
Line 16:		Line 16:

	Factors contributing to the formation of ITBs include:		Factors contributing to the formation of ITBs include:
	<ref>~~[http://dx.doi.org/10.1088/0029-5515/44/4/R01~~ J.W. Connor et al, ''A review of internal transport barrier physics for steady-state operation of tokamaks'', Nucl. Fusion '''44''' (2004) R1-R49]</ref>		<ref>J.W. Connor et al, ''A review of internal transport barrier physics for steady-state operation of tokamaks'', [[doi:10.1088/0029-5515/44/4/R01\|Nucl. Fusion '''44''' (2004) R1-R49]]</ref>
	* The power deposited inside the [[Flux surface\|magnetic surface]], and/or local pressure gradients		* The power deposited inside the [[Flux surface\|magnetic surface]], and/or local pressure gradients
	* [[Magnetic shear]] and the shape of the [[Rotational transform\|rotational transform]] profile (e.g., reversed shear)		* [[Magnetic shear]] and the shape of the [[Rotational transform\|rotational transform]] profile (e.g., reversed shear)
	* MHD activity		* MHD activity
	* Momentum torques (poloidal or toroidal)		* Momentum torques (poloidal or toroidal)
	* Enhanced collisionless losses of trapped particles, generating a radial electric field <ref>~~[http://link.aps.org/doi/10.1103/PhysRevLett.86.5910~~ U. Stroth et al, ''Internal Transport Barrier Triggered by Neoclassical Transport in W7-AS'', Phys. Rev. Lett. '''86''' (2001) 5910 - 5913]</ref>		* Enhanced collisionless losses of trapped particles, generating a radial electric field <ref>U. Stroth et al, ''Internal Transport Barrier Triggered by Neoclassical Transport in W7-AS'', [[doi:10.1103/PhysRevLett.86.5910\|Phys. Rev. Lett. '''86''' (2001) 5910 - 5913]]</ref>
	* Reduced collisional damping, allowing the growth of zonal flows <ref>~~[http://link.aip.org/link/?PHPAEN/14/020702/1~~ K. Itoh et al, ''Physics of internal transport barrier of toroidal helical plasmas'', Phys. Plasmas '''14''' (2007) 020702]</ref>		* Reduced collisional damping, allowing the growth of zonal flows <ref>K. Itoh et al, ''Physics of internal transport barrier of toroidal helical plasmas'', [[doi:10.1063/1.2435310\|Phys. Plasmas '''14''' (2007) 020702]]</ref>

	The relation between some of these factors can be understood from the steady state ion force balance for the radial electric field:		The relation between some of these factors can be understood from the steady state ion force balance for the radial electric field: