README	file	for	Myers,	et	al.	Nature	letter	titled,	“A	dynamic	magnetic	tension	force	as	the	cause	of	failed	solar	eruptions.”		Each	figure	has	an	accompanying	PDF	of	the	figure	itself	and	an	HDF5	file	of	the	archived	figure	data.		The	contents	of	each	HDF5	file	are	described	below.			Normalization	factors	used	throughout:	• τA	=	3.2	μs	• xf	=	18	cm			Figure	1:		Representative	stable	and	erupting	flux	rope	discharges	• Note	that	the	HDF5	file	for	this	figure	also	contains	the	data	for	the	Supplementary	Video	that	accompanies	this	paper	• panel_a		o No	data	• panel_b	o contour_data_stable	! time_vec	=	time	vector	for	the	‘stable’	contour	[normalized	to	τA]	! zapex_vec	=	height	vector	for	the	‘stable’	contour	[normalized	to	xf]	! Note	that	‘NaN’	values	are	used	to	separate	the	individual	contour	segments	o contour_data_erupting	! time_vec	=	time	vector	for	the	‘erupting’	contours	[normalized	to	τA]	! zapex_vec	=	height	vector	for	the	‘erupting’	contours	[normalized	to	xf]	! NaN	values	are	inserted	to	separate	individual	contour	segments	o time_pts	=	the	four	time	points	expanded	in	(c),	(d)	[normalized	to	τA]	• panel_c	o shot_number	=	MRX	shot	number	for	the	data	in	this	panel	[Shot	153992]	o time_vec	=	vector	of	frame	times	[normalized	to	τA]	o Note	that	the	data	for	all	frames	used	to	create	Supplementary	Video	1	are	included	in	this	HDF5	file.		Only	frames	147,152,157,	and	162	are	used	in	the	print	figure.	o frame[000,270]	! time_pt	=	time	of	the	frame	[normalized	to	τA]	! color_data	• [x,z]grid	=	x,z	grid	on	which	the	color	data	are	plotted	[cm]	• By_data	=	out-of-plane	(poloidal)	magnetic	field	data	[G]	! magax_data	• [x,z]vec	=	x,z	vectors	for	the	magnetic	axis	contours	[cm]	• NaN	values	are	inserted	to	separate	the	individual	contour	segments	! image_data	• image_index	=	frame	number	from	the	fast	camera	video	• image_time	=	timestamp	of	the	fast	camera	image	[normalized	to	τA]	• image	=	raw	fast	camera	image	data	[monochrome]	• panel_d	o Identical	to	panel_c,	except	for	Shot	154172	instead	of	Shot	153992			Figure	2:		The	experimentally	measured	torus	versus	kink	instability	parameter	space	
• qa_vec		=	vector	of	ensemble-averaged	edge	safety	factor,	qa	[dimensionless]	• n_vec	=	vector	of	ensemble-averaged	field	decay	index,	n	[dimensionless]	• dz_vec	=	vector	of	ensemble-averaged	instability	amplitude,	〈δz〉/xf	[normalized	to	xf]	• qa_thresh	=	empirically	identified	kink	instability	threshold	window	[dimensionless]	• n_thresh	=	empirically	identified	torus	instability	threshold	window	[dimensionless]			Figure	3:		Magnetic	analysis	of	a	characteristic	failed	torus	event	• shot_number	=	MRX	shot	number	for	the	data	in	this	figure	[Shot	154410]	• panel_a:	o time_vec_failed	=	time	vector	for	this	panel	[normalized	to	τA]	o height_vec_failed	=	height	vector	for	the	failed	flux	rope	evolution	[normalized	to	xf]	o time_pts	=	the	four	time	points	evaluated	in	(d),	(e)	[normalized	to	τA]	• panel_b:	o time_vec	=	time	vector	for	this	panel	[normalized	to	τA]	o flux_pol_vec	=	vector	of	poloidal	flux	as	a	function	of	time	[mWb]	o flux_tor_vec	=	vector	of	toroidal	flux	as	a	function	of	time	[mWb]	o time_pts	=	the	four	time	points	evaluated	in	(d),	(e)	[normalized	to	τA]	• panel_c:	o time_vec	=	time	vector	for	this	panel	[normalized	to	τA]	o Fh_vec	=	vector	of	the	hoop	force	as	a	function	of	time	[N/m]	o Fs_vec	=	vector	of	the	strapping	force	as	a	function	of	time	[N/m]	o FT_plus_Fs_vec	=	vector	of	the	toroidal	field	forces	plus	the	strapping	force	as	a	function	of	time	[N/m]	o time_pts	=	the	four	time	points	evaluated	in	(d),	(e)	[normalized	to	τA]	• panel_d,	subpanels_[1,2,3,4]	o annotation_data	! electrode_[y,z]vec	=	y,z	points	for	the	electrode	annotation	[cm]	! probe_pts_[y,z]vec	=	y,z	locations	of	the	magnetic	field	measurements	[cm]	! vessel_wall_[y,z]vec	=	y,z	profile	of	the	vacuum	vessel	wall	[cm]	o color_data	! [y,z]grid	=	y,z	grid	on	which	the	color	data	are	plotted	[cm]	! JT_data	=	toroidal	current	density	data	[MA	⋅ m-2]	o vector_data	! [y,z]grid	=	y,z	grid	on	which	the	vector	data	are	plotted	[cm]	! BP_v[y,z]	=	y,z	vector	components	of	the	poloidal	magnetic	field	[G]	• panel_e,	subpanels_[1,2,3,4]	o annotation_data	=	identical	to	panel_d	o color_data	! [y,z]grid	=	y,z	grid	on	which	the	color	data	are	plotted	[cm]	! BTi_data	=	internal	(plasma	produced)	toroidal	magnetic	field	data	[G]			Figure	ED-1:		Experimental	setup	• No	data			Figure	ED-2:		Components	of	the	potential	magnetic	field	configuration	
• No	data			Figure	ED-3:		Magnetic	analysis	of	a	characteristic	eruptive	event	• Identical	to	Figure	3,	except	for	Shot	153884	instead	of	Shot	154410			Figure	ED-4:		Sample	in	situ	magnetic	field	measurements	• panel_a	o shot_number	=	MRX	shot	number	for	the	data	in	this	panel	[Shot	153992]	o annotation_data	! electrode[1,2]_[x,z]vec	=	x,z	points	for	electrode	1,2	annotations	[cm]	! probe_pts_[x,z]vec	=	x,z	locations	of	the	magnetic	field	measurements	[cm]	! vessel_wall_[x,z]vec	=	x,z	profile	of	the	vacuum	vessel	wall	[cm]	! shifted_circle_[x,z]vec	=	x,z	profile	of	the	shifted-circle	approximation	for	the	magnetic	axis	[cm]	o color_data	! 	[x,z]grid	=	x,z	grid	on	which	the	color	data	are	plotted	[cm]	! BP_data	=	poloidal	magnetic	field	data	[G]	o vector_data	! [x,z]grid	=	x,z	grid	on	which	the	vector	data	are	plotted	[cm]	! BTi_v[x,z]	=	x,z	vector	components	of	the	internal	toroidal	magnetic	field	[G]	o magax_data	! contour_[x,z]grid	=	x,z	grid	on	which	the	magnetic	axis	is	computed	[cm]	! contour_BP_data	=	out-of-plane	poloidal	magnetic	field	data	for	computing	the	magnetic	axis	[G]	! contour_level	=	BP	contour	level	for	computing	the	magnetic	axis	[G]	• panel_b	o shot_number	=	MRX	shot	number	for	the	data	in	this	panel	[Shot	154288]	o annotation_data	=	identical	to	Fig.	3,	panel	(d)	o color_data	! [y,z]grid	=	y,z	grid	on	which	the	color	data	are	plotted	[cm]	! BTi_data	=	internal	toroidal	magnetic	field	data	[G]	o vector_data	! [y,z]grid	=	y,z	grid	on	which	the	vector	data	are	plotted	[cm]	! BP_v[y,z]	=	y,z	vector	components	of	the	poloidal	magnetic	field	[G]	o magax_data	! magax_[y,z]val	=	spatial	point	where	the	magnetic	axis	is	located	[cm]			Figure	ED-5:		Height-time	plots	from	four	representative	flux	rope	discharges	• panel_a	o time	=	time	vector	for	this	panel	[normalized	to	τA]	o IT_mean	=	mean	plasma	current	waveform	[kA]	o IT_stddev	=	standard	deviation	of	the	plasma	current	waveform	[kA]	• panel_b,	subpanel_[1,2,3,4]	o shot_number	=	MRX	shot	number	for	the	data	in	this	panel	o color_data	! tgrid	=	time	grid	on	which	the	color	data	are	plotted	[normalized	to	τA]	
! zgrid	=	z	grid	on	which	the	color	data	are	plotted	[normalized	to	xf]	! By_data	=	out-of-plane	magnetic	field	data	[G]	o contour_data	! time_vec	=	time	vector	for	the	zapex	contours	[normalized	to	τA]	! zapex_vec	=	height	vector	for	the	zapex	contours	[normalized	to	xf]	! time_vec_avg	=	time	vector	for	the	〈zapex〉	contours	[normalized	to	τA]	! zapex_vec_avg	=	height	vector	for	the	〈zapex〉	contours	[normalized	to	xf]	! NaN	values	are	inserted	to	separate	individual	contour	segments			Figure	ED-6:		Magnetic	field	and	current	density	data	for	computing	flux	rope	forces	• panel_left	o annotation_data	=	identical	to	Fig.	3,	panel	(d)	o color_data	! [y,z]grid	=	y,z	grid	on	which	the	color	data	are	plotted	[cm]	! JT_data	=	toroidal	current	density	data	[MA	⋅ m-2]	o vector_data	! [y,z]grid	=	y,z	grid	on	which	the	vector	data	are	plotted	[cm]	! BP_v[y,z]	=	y,z	vector	components	of	the	poloidal	magnetic	field	[G]	o magax_data	! magax_[y,z]val	=	spatial	point	where	the	magnetic	axis	is	located	[cm]	o contour_data	! [y,z]grid	=	y,z	grid	on	which	the	contours	are	computed	[cm]	! psi_data	=	poloidal	flux	function	data	for	contour	computation	[Wb	⋅ m-1]	! contour_levels_blue	=	levels	used	to	plot	the	blue	contours	[Wb	⋅ m-1]	! contour_level_red	=	level	used	to	plot	the	single	red	contour	[Wb	⋅ m-1]	• panel_right	o annotation_data	=	identical	to	Fig.	3,	panel	(d)	o color_data	! [y,z]grid	=	y,z	grid	on	which	the	color	data	are	plotted	[cm]	! BTi_data	=	internal	toroidal	magnetic	field	data	[G]	o vector_data	! [y,z]grid	=	y,z	grid	on	which	the	vector	data	are	plotted	[cm]	! JP_v[y,z]	=	y,z	vector	components	of	the	poloidal	current	density	[MA	⋅ m-2]	o magax_data	! magax_[y,z]val	=	spatial	point	where	the	magnetic	axis	is	located	[cm]