GEOGRAPHIC AND SEGMENT INFORMATION - Reportable Segment (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022
Segment Reporting Information [Line Items]
Sales	$ 13,569	$ 10,292	$ 25,711	$ 22,785
(Loss) income from operations	(1,235)	(5,976)	(6,846)	(11,847)	$ (23,600)
Interest income	179	18	230	20
Interest expense	(543)	(3)	(777)	(11)
Other income (loss), net	646	607	641	586
Income tax expense (benefit)	66	96	(2,201)	166
Operating Segments | Advanced Energy
Segment Reporting Information [Line Items]
Sales	11,722	8,364	21,412	19,178
(Loss) income from operations	747	(1,252)	(579)	(2,591)
Interest income	0	0	0	0
Interest expense	0	0	0	0
Other income (loss), net	0	0	0	0
Income tax expense (benefit)	0	0	0	0
Operating Segments | OEM
Segment Reporting Information [Line Items]
Sales	1,847	1,928	4,299	3,607
(Loss) income from operations	353	469	1,204	786
Interest income	0	0	0	0
Interest expense	0	0	0	0
Other income (loss), net	0	0	0	0
Income tax expense (benefit)	0	0	0	0
Corporate & Other
Segment Reporting Information [Line Items]
Sales	0	0	0	0
(Loss) income from operations	(2,335)	(5,193)	(7,471)	(10,042)
Interest income	179	18	230	20
Interest expense	(543)	(3)	(777)	(11)
Other income (loss), net	646	607	641	586
Income tax expense (benefit)	$ 66	$ 96	$ (2,201)	$ 166