TJ-II:Blobs vs streamers - Revision history

Admin at 09:29, 1 August 2025

2025-08-01T09:29:34Z

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	== Description of the activity, including motivation/objectives and experience of the proponent (typically one-two pages)==		== Description of the activity, including motivation/objectives and experience of the proponent (typically one-two pages)==
	According to a recent suggestion by Chang<ref>C. Chang et al., Self-organization between the neoclassical and turbulent transports across the separatrix surface, resulting in the regulation of the divertor heat-load width, [https://users.euro-fusion.org/repository/pinboard/EFDA-JET/conference/59091_chang.c-th-d-synopsis2.pdf Synopsis for IAEA Conference (2018)]</ref>, turbulence in the edge can be of 'blob type' or 'streamer type'.		According to a recent suggestion by Chang<ref>C. Chang et al., Self-organization between the neoclassical and turbulent transports across the separatrix surface, resulting in the regulation of the divertor heat-load width, [https://users.euro-fusion.org/repository/pinboard/EFDA-JET/conference/59091_chang.c-th-d-synopsis2.pdf Synopsis for IAEA Conference (2018)]</ref>, turbulence in the edge can be of 'blob type' or 'streamer type'.
	Chang states: ‘A weak mean <math> E × B</math> shear, due to the small <math>\rho_i/L</math> effect, allows the formation of the streamer type turbulence.’		Chang states: ‘A weak mean <math> E \times B</math> shear, due to the small <math>\rho_i/L</math> effect, allows the formation of the streamer type turbulence.’

	We propose studying this effect, not by varying <math>B</math>, but rather by varying <math>E</math>. To do so, we will scan the edge <math>E_r</math> from negative to positive (crossing zero), either by biasing or by varying the mean density near the spontaneous transition value (<math>n_e \simeq 0.6 ⋅ 10^{19}</math>). Near zero Er, transport across the LCFS should be more streamer-like.		We propose studying this effect, not by varying <math>B</math>, but rather by varying <math>E</math>. To do so, we will scan the edge <math>E_r</math> from negative to positive (crossing zero), either by biasing or by varying the mean density near the spontaneous transition value (<math>n_e \simeq 0.6 \cdot 10^{19}</math>). Near zero Er, transport across the LCFS should be more streamer-like.

	Measurements to make: In this scan, we will measure: Isat decay length in SOL (if possible - this may require several discharges), and <math>\omega_S</math>.<ref>P. Manz, T. Ribeiro, B. Scott, G. Birkenmeier, D. Carralero, G. Fuchert, S. Müller, H. Müller, U. Stroth, and E. Wolfrum. Origin and turbulence spreading of plasma blobs. [[doi:10.1063/1.4908272\|Phys. Plasmas, 22:022308, 2015]]</ref>		Measurements to make: In this scan, we will measure: Isat decay length in SOL (if possible - this may require several discharges), and <math>\omega_S</math>.<ref>P. Manz, T. Ribeiro, B. Scott, G. Birkenmeier, D. Carralero, G. Fuchert, S. Müller, H. Müller, U. Stroth, and E. Wolfrum. Origin and turbulence spreading of plasma blobs. [[doi:10.1063/1.4908272\|Phys. Plasmas, 22:022308, 2015]]</ref>

Admin at 09:23, 27 March 2018

2018-03-27T09:23:02Z

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	[[Category:TJ-II internal documents]]		[[Category:TJ-II internal documents]]
	[[Category:TJ-II experimental proposals]]		[[Category:TJ-II experimental proposals Spring 2018]]

Admin: /* Description of required resources */

2018-03-22T11:01:31Z

Description of required resources

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	== Description of required resources ==		== Description of required resources ==
	Required resources:		Required resources:
	* Number of plasma discharges or days of operation: at least 1		* Number of plasma discharges or days of operation: at least 1 day
	* Essential diagnostic systems: Langmuir probe (2-dimensional), biasing probe		* Essential diagnostic systems: Langmuir probe (2-dimensional), biasing probe
	* Type of plasmas (heating configuration): ECRH		* Type of plasmas (heating configuration): ECRH

Admin: /* Description of the activity, including motivation/objectives and experience of the proponent (typically one-two pages) */

2018-03-22T11:01:06Z

Description of the activity, including motivation/objectives and experience of the proponent (typically one-two pages)

← Older revision		Revision as of 13:01, 22 March 2018
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	We propose studying this effect, not by varying <math>B</math>, but rather by varying <math>E</math>. To do so, we will scan the edge <math>E_r</math> from negative to positive (crossing zero), either by biasing or by varying the mean density near the spontaneous transition value (<math>n_e \simeq 0.6 ⋅ 10^{19}</math>). Near zero Er, transport across the LCFS should be more streamer-like.		We propose studying this effect, not by varying <math>B</math>, but rather by varying <math>E</math>. To do so, we will scan the edge <math>E_r</math> from negative to positive (crossing zero), either by biasing or by varying the mean density near the spontaneous transition value (<math>n_e \simeq 0.6 ⋅ 10^{19}</math>). Near zero Er, transport across the LCFS should be more streamer-like.

	Measurements to make: In this scan, we will measure: Isat decay length in SOL (if possible - this may require several discharges), and omega_S.<ref>P. Manz, T. Ribeiro, B. Scott, G. Birkenmeier, D. Carralero, G. Fuchert, S. Müller, H. Müller, U. Stroth, and E. Wolfrum. Origin and turbulence spreading of plasma blobs. [[doi:10.1063/1.4908272\|Phys. Plasmas, 22:022308, 2015]]</ref>		Measurements to make: In this scan, we will measure: Isat decay length in SOL (if possible - this may require several discharges), and <math>\omega_S</math>.<ref>P. Manz, T. Ribeiro, B. Scott, G. Birkenmeier, D. Carralero, G. Fuchert, S. Müller, H. Müller, U. Stroth, and E. Wolfrum. Origin and turbulence spreading of plasma blobs. [[doi:10.1063/1.4908272\|Phys. Plasmas, 22:022308, 2015]]</ref>

	We will also attempt to quantify 'blobbiness', in order to detect the transition between 'blob-type' and 'streamer-type' turbulence. This difference might also be reflected in the radial correlation length (or causality, cf. Transfer Entropy). Perhaps there are other ways to quantify the difference between 'blob-type' and 'streamer-type' turbulence.		We will also attempt to quantify 'blobbiness', in order to detect the transition between 'blob-type' and 'streamer-type' turbulence. This difference might also be reflected in the radial correlation length (or causality, cf. Transfer Entropy). Perhaps there are other ways to quantify the difference between 'blob-type' and 'streamer-type' turbulence.

Admin: Created page with "== Experimental campaign == 2018 Spring == Proposal title == '''Blobs vs streamers''' == Name and affiliation of proponent == G. Grenfell, B.Ph. van Milligen == Details of ..."

2018-03-06T13:51:40Z

Created page with "== Experimental campaign == 2018 Spring == Proposal title == '''Blobs vs streamers''' == Name and affiliation of proponent == G. Grenfell, B.Ph. van Milligen == Details of ..."

New page

== Experimental campaign ==
2018 Spring

== Proposal title ==
'''Blobs vs streamers'''

== Name and affiliation of proponent ==
G. Grenfell, B.Ph. van Milligen

== Details of contact person at LNF (if applicable) ==
B.Ph. van Milligen

== Description of the activity, including motivation/objectives and experience of the proponent (typically one-two pages)==
According to a recent suggestion by Chang<ref>C. Chang et al., Self-organization between the neoclassical and turbulent transports across the separatrix surface, resulting in the regulation of the divertor heat-load width, [https://users.euro-fusion.org/repository/pinboard/EFDA-JET/conference/59091_chang.c-th-d-synopsis2.pdf Synopsis for IAEA Conference (2018)]</ref>, turbulence in the edge can be of 'blob type' or 'streamer type'.
Chang states: ‘A weak mean <math> E × B</math> shear, due to the small <math>\rho_i/L</math> effect, allows the formation of the streamer type turbulence.’

We propose studying this effect, not by varying <math>B</math>, but rather by varying <math>E</math>. To do so, we will scan the edge <math>E_r</math> from negative to positive (crossing zero), either by biasing or by varying the mean density near the spontaneous transition value (<math>n_e \simeq 0.6 ⋅ 10^{19}</math>). Near zero Er, transport across the LCFS should be more streamer-like.

Measurements to make: In this scan, we will measure: Isat decay length in SOL (if possible - this may require several discharges), and omega_S.<ref>P. Manz, T. Ribeiro, B. Scott, G. Birkenmeier, D. Carralero, G. Fuchert, S. Müller, H. Müller, U. Stroth, and E. Wolfrum. Origin and turbulence spreading of plasma blobs. [[doi:10.1063/1.4908272|Phys. Plasmas, 22:022308, 2015]]</ref>

We will also attempt to quantify 'blobbiness', in order to detect the transition between 'blob-type' and 'streamer-type' turbulence. This difference might also be reflected in the radial correlation length (or causality, cf. Transfer Entropy). Perhaps there are other ways to quantify the difference between 'blob-type' and 'streamer-type' turbulence.

== If applicable, International or National funding project or entity ==
N/A

== Description of required resources ==
Required resources:
* Number of plasma discharges or days of operation: at least 1
* Essential diagnostic systems: Langmuir probe (2-dimensional), biasing probe
* Type of plasmas (heating configuration): ECRH
* Specific requirements on wall conditioning if any: N/A
* External users: need a local computer account for data access: no
* Any external equipment to be integrated? Provide description and integration needs: N/A

== Preferred dates and degree of flexibility ==
Preferred dates: N/A

== References ==
<references /> 

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